tallow for laying hens (poultry, fat ......finally, deepest appreciation to my wife, bushra, for her...
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TALLOW FOR LAYING HENS (POULTRY,FAT, PERFORMANCE, AMINO ACIDS).
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Authors BACO, ABDUL-AZIZ ISHAK.
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Baco, Abdul·Aziz Ishak
TALLOW FOR LAYING HENS
The University of Arizona
University Microfilms
International 300 N. Zeeb Road, Ann Arbor, MI48106
8603334
PH.D. 1985
TALLOW FOR LAYING HENS
by
Abdul-Aziz Ishak Baco
A Dissertation Submitted to the Faculty of the
COMMITTEE ON NUTRITIONAL SCIENCES (GRADUATE)
In Partial Fulfillment of the Requirements for the Degree of
DOCTOR OF PHILOSOPHY
In the Graduate College
THE UNIVERSITY OF ARIZONA
1 985
THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE
As members of the Final Examination Committee, we certify that we have read
the dissertation prepared by Abdul-Aziz Ishak Baco --------------------------------------------
entitled TALLOW FOR LAYING HENS ------------------------------------------------------------
and recommend that it be accepted as fulfilling the dissertation requirement
for the Degree of Doctor of Philosophy
~~ss(L ~ ,K g~i2
Date
Date
Date
Date" /
Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College.
I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement.
Dissertation Director Date
STATEMENT BY AUTHOR
This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.
Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Request for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the materials is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.
SIGNED
DEDICATION
In the name of ALLAH (God),
the most merciful,
the most compassionate
01 ~ 1 ii 'J \
01 I . 'L......... ~Yr' ... ..)
If .L;~1 .. ~ l\ ~ . U--
·0 . ?" '1
To my parents to whom lowe everything,
To my three daughters (Amena, Asma and Alaa)
with them I shall ask Allah to protect me from the hell fire,
To my lovely wife
iii
ACKNOWLEDGEMENTS
The author is sincerely grateful to Dr. Bobby L. Reid for his
guidance, encouragement and continued moral support throughout the
entire graduate program and the accomplishment of this project.
Appreciation is also due to the committee members, Drs. J. A.
Marchello, R. L. Price, W. H. Brown, and M. R. Selke for their
suggestions and constructive criticisms.
Special thanks to Phyllis Maiorino for her contribution in
editing this dissertation, and to Rebecca Mitchell and Angelo Longo as
well as to the staff of the Poultry Research Center for their technical
assistance during the research period.
The author would like to thank his family members, parents
and brothers, Abdul-Sattar, Mohammad Ali, for their help and
encouragement.
Finally, deepest appreciation to my wife, Bushra, for her
sacrifice, support, understanding and encouragement throughout my
academic program.
I.
II.
III.
TABLE OF CONTENTS
LIST OF TABLES • • • •
LIST OF ILLUSTRATIONS
ABSTRACT • • •
INTRODUCTION
LITERATURE REVIEW
EFFECTS OF ADDED TALLOW ON DIETARY NUTRIENT UTILIZATION Introduction • • • • • Experimental Procedure • Results and Discussion • S UIIIIIla ry . . . . . . . . . . . .
IV. EFFECTS OF TALLOW SUPPLEMENTATION IN MINIMAL AMINO ACID DIETS
Introduction • • • • • • Experimental Procedure • Results and Discussion. Summary
REFERENCES • •
v
Page
vi
vii
. viii
1
3
19 19 20 24 36
38 38 40 43 51
53
LIST OF TABLES
Table Page
1. Composition of basal diet (Experiment 1) 21
2. Fatty acid composition of tallow 23
3. Tallow supplementation and laying hen performance (Experiment 1) . . . • • • . . • •••••. 25
4. Effect of dietary tallow level on energy utilization in laying hens (Experiment 1) . • . • • • • • • 27
5. Effects of environmental temperature and age on laying hen performance (Experiment 1) • • • • • • • • • • • • 30
6. Effect of laying hen age on ME of tallow (Experiment 1) 32
7. Effect of tallow on nutrient utilization (Experiment 1) 32
8. Effect of tallow supplementation on average amino acid retention by laying hens (Experiment 1) • 34
9. Effect of tallow supplementation on average fatty acid retention by laying hens (Experiment 1) • • 35
10. Temperature means during experimental periods (Experiment 2) • • • • • • • • • • 41
11. Composition of experimental diets (Experiment 2) 42
12. Tallow, protein and amino acid composition of experimental diets (Experiment 2) • • • • • • •
~3. Effects of experimental diets on performance of laying
44
hens housed at different temperatures (Experiment 2) 45
14. Experimental diet effects on energy utilization by laying hens housed at different temperatures (Experiment 2) 49
vi
Figure
1.
LIST OF ILLUSTRATIONS
Partition of ingested energy
Vl.l.
Page
8
ABSTRACT
Effects of tallow supplementation on dietary nutrient and
minimal amLno acid utilization in the laying hen were studied in two
experiments. In the first experiment diets contained six levels of
animal tallow ranging from 0 to 10%. Percent egg production and egg
mass were not significantly affected by tallow. Body weight was
significantly increased by 2% tallow was maximum at 6%. Addition of up
to 6% fat improved feed conversion without adversely affecting other
production characteristics. Metabolizable energy (ME) intake increased
from 305.1 to 322.4 kcal/hen/d over the range of 0 to 6% tallow with no
further improvement at higher tallow levels. Maximum net energetic
efficiency was obtained with 2 and 4% tallow.
Ability to digest tallow declined significantly with hen age.
Higher tallow ME values were obtained from calorimetry data than from
digestibility measurements due to beneficial effects of tallow on
digestibilities of fat and protein in the basal diet. No improvement
in starch retention was observed with tallow supplementation.
In the second experiment, diets containing four levels of
protein (15.0, 13.6, 15.0 + methionine, and 17.0%) without and with 3%
tallow were fed to hens housed in an open cage house or an insulated,
evaporatively cooled house. Egg production and egg mass were
significantly higher in the insulated house.
viii
1X
This study indicates that reducing total protein below the
National Research Council (NRC, 1984) recommended level significantly
reduced egg production by birds housed in an open house. Supplemental
methionine to provide .60% TSAA was required for maximum egg
production. Egg production was significantly improved with the low
protein diet when 3% tallow was added; however, egg production rate
supported by this combination was significantly below that obtained
with the 17% protein diet either with or without added tallow.
For birds housed in the insulated, evaporatively cooled house
the diet based on the NRC amino acid recommendations appeared to be
optimal for performance, even with a lower protein level. No
additional benefits were obtained in egg production with 3% tallow in
any of the diets under these housing conditions.
CHAPTER 1
INTRODUCTION
The greatest part of the cost of a balanced poultry diet is
incurred in providing energy, and fats have been an important source of
dietary energy for poultry for more than 25 years. In addition to
providing energy in a concentrated form, fats often have a favorable
influence on performance and physical characteristics of the diet.
Improved laying hen performance occurs as a result of the
"extra caloric effect" as reported by Carew and Hill (1964), Touchburn
and Naber (1966) and Jensen, Schumaier and Latshaw (1970). They found
that fat supplementation resulted in greater improvements in
performance than were expected from the increased energy content of the
diet. This effect has been suggested to be totally due to reduced heat
increment (HI) or increased assoc iative dynamic effect. The" extra
caloric effect" has also been attributed to an increase in net
energetic efficiency resulting from improved utilization of
metabolizable energy (ME) with the addition of fat.
There is another phenomenon which occurs at the absorption
level and is measurable as increased ME values with fat
supplementation. The synergism between the supplemental fat and the
basal fat in the test diet often causes improved absorption of the
supplemental fat, thereby increasing ME (Young and Garrett, 1963;
Sibbald and Kramer, 1978). The size of this improvement depends on the
1
2
type of added fat and the level of application, as well as the type of
basal diet used. In addition, fat may enhance the absorbability of the
non-fat portion of the test diet by slowing the rate of food passage
(Mateos and Sell, 1980a). This effect commonly results 1n a calculated
ME value for fat which exceeds its gross energy (GE) value. This
greater than expected ME value was called "extra metabolic effect" by
Horani and Sell (1977a) to distinguish it from the "extra caloric
effec t" of decreased HI.
The profitable effects of supplemental fats in nutritionally
balanced rations on poultry performance were reported a number of years
ago by Yacowitz (1953), Lillie et~. (1952), Dam ~ al. (1959)
and Gerry (1963). Feed efficiency improvements are noted consistently,
and frequently productive performance is improved.
Environmental temperature is another factor which affects the
bird's energy needs. Efficient poultry production requires that
dietary composition change with environmental teffiperature. At low
environmental temperatures more ME is needed to maintain body
temperature which can be done by consuming more feed or at the expense
of energy use for production at limited feed intakes. More energy is
needed to dissipate heat produced during periods of high environmental
temperature and results in lowered energetic efficiency. If energy
intake decreases during high ambient temperatures, the dietary
concentration of nutrients must increase and vice versa.
CHAPTER 2
LITERATURE REVIEW
Feed represents 70-75% of poultry production cost (John,
1976) and 67% of the cost of egg production when pullet rearing costs
are included (Hill and Hunt, 1980). Feed intake, with a few
exceptions, is inversely related to dietary energy concentration;
consequently, nutrient intake can be regulated by control of dietary
energy:nutrient ratios. Feed intake is controlled by the available
energy of the diet; therefore, accurate dietary energy measurements are
needed if inputs and outputs are to be manipulated to provide optimum
productivity and maximum benefits.
Animals eat to meet their energy requirements, and dietary
nutrient intakes usually depend upon dietary energy density. Kleiber
(1945) concluded that available energy should be the baseline for
establishing nutrient requirements. An inverse relationship between
feed intake and dietary energy density was found by Warkentin,
Warkentin and Ivy (1943), and they proposed that rats eat for calories.
Peterson, Grau and Peek (1945) found that chicks attempt to eat to
satisfy their energy requirements only at high dietary energy
concentrations. Moreover, Powell ~ al. (1974) stated that feed
intake of hens decreases when a sucrose solution was substituted for
drinking water. Also, Gleaves and Salim (1982) reported that hens fed
2% lactose had reduced feed intakes.
3
4
There are some conditions in which animals do not eat to
satisfy their energy requirements •. Low energy diets, due to physical
incapacity (bulk) reduce feed consumption, and unpalatable feeds may
not be consumed in adequate amounts (Davidson ~ ~., 1961).
Laying hens tend to overconsume energy when dietary energy levels were
raised by inclusion of up to 11% tallow (Dillon, 1974). Dale and
Fuller (1979) reported that as energy from fat replaced that from
carbohydrate, chicks increased their energy intake as dietary energy
concentration increased. The increase in energy intake associated with
high fat qiets may be due in part to a reduction in HI. An appetite
for calcium in laying hens was found to result in surplus feed intake
by Mongin and Sauveur (1974). Davidson ~ al. (1961) reported that
chicks tended to make up for an amino acid imbalance by increasing feed
intake. Solberg (1971) also reported that birds increased feed intake
to compensate for a mild lysine deficiency.
Birds are homeotherms and as such their energy requirements
are determined in part by environmental temperature. Scott, Matterson
and Singsen (1947) were among the first to indicate that rations high
in energy content tended to stimulate more rapid growth and better feed
conversion in chickens than rations of lower energy content. Adams
et al. (1962a) and Dale and Fuller (1980) found that increased -- --dietary energy resulted in improved growth and feed conversion in both
a cyclic hot temperature system (23 to 33 to 23°C) and a cool
environment (14 to 22°C). The effects of two energy levels (2830 and
3300 kcal ME/kg) were measured with broilers reared at two temperatures
(21 and 32°C) by Adams et al., (1962a), and they suggested that
the adverse effects of the 32°C temperature could not be offset by
increasing dietary energy level. Vohra, Wilson and Siopes (1979)
reported that maintenance energy requirements (ME ) with diets m
containing 2830 or 1980 kcal/kg were 132.6 and 171.3 kcal/kg· 75 /d,
respectively, at 15.6°c, and 114.9 and 140.2 kcal/kg· 75 /d at
26.7°C. Hurwitz, Sklan and Bartov (1978) also found that maintenance
energy requirements (ME ) decreased as the temperature increased from m
12 to 24°C. The lowest energy requirements for maintenance were
between 24 and 28°C, and as temperature was elevated above 28°C,
maintenance energy requirements increased.
Bacon, Cantor and Coleman (1981) estimated the effects of
three dietary energy levels ranging from 3090 to 3310 kcal ME/kg on
broilers grown in a cool (23°C) or a warm (26°C) environment. Energy
level did not significantly affect body weights at 49 days of age ~n
5
either environment. Reece and McNaughton (1982) reported no changes ~n
7-week body weights due to dietary energy level when broilers were
reared at 26.7°C. However, rearing broilers at 18.3°C resulted in a
3.1% increase in body weight as dietary energy level increased from
3175 to 3325 kcal ME/kg.
Feed intake, a necessary element when considering nutritional
requirements of chickens, is inversely correlated with environmental
temperature and dietary energy (Dale and Fuller, 1980). Hurwitz et
~. (1978) indicated that feed intake declined due to the decreasing
maintenance energy requirements as temperature increased up to 27°C.
Increasing dietary energy with supplemental animal or
vegetable fat improved growth and feed utilization of broilers grown at
6
21 or 29°C environments (Mickelberry, RogIer and Stadelman, 1966).
However, Dale and Fuller (1980) found that growth was not affected by
added fat when broilers were reared at a constant 31°C. Reid (1981)
found that supplemental tallow, at levels of 1-5% increased consumption
of ME above maintenance at temperatures above 27°C and resulted in
improved egg production.
The lower critical temperature (CT) is the environmental
temperature below which heat production of a fasting, resting animal
will increase to prevent lowering of body temperature. Mitchell and
Haines (1927) found the average CT of laying hens to be 17°C; while,
Barott and Pringle (1946) found metabolism of laying hens to be minimal
at 21°C. However, Kleiber and Dougherty (1934) found no evidence of a
CT in laying hens. Under practical conditions, poultry are seldom
fasted; consequently, the concept of a thermoneutral zone (TNZ) seems
to have greater application than CT. The TNZ is defined as lithe
effective ambient temperature where heat production at the
thermoneutral rate is offset by net heat loss to environment without
aid of special heat conserving or heat dissipating mechanism ll (National
Research Council (NRC), 1981). The relationship of poultry to their
thermal environment was studied by Osbaldiston and Sainsbury (1963),
and they found that substantial improvements in feed efficiency
occurred as the temperature increased from 12 to 15 to 18°C.
An inverse relationship between environmental temperature and
feed intake occurs in laying hens although time is required to
acclimatize to a change in the ambient temperature (Davis, Hassan and
Sykes, 1972). The decline in energy intake with increases Ln
7
environmental temperature was quantitated as: ME (kcal/body weight
kg· 75 )/d = 203 - 1.13T where T is ambient temperature in degrees
Celsius (Davis ~~., 1973). Interestingly, there was no CT or
TNZ predicted by this regression, and egg production was normal within
the temperature range of 7.2 to 35°C. The practical importance of
this relationship is explained by Daghir (1973) who found a seasonable
variation of 10-15% in energy intakes for laying hens. Emmans (1974)
has also derived regression equations which predict voluntary energy
intake for laying hens under specific conditions.
Efficient poultry production demands that dietary composition
change with the environmental temperature. As feed intake decreases
with higher energy diets, the dietary concentration of nutrients
relative to available energy must be maintained in order to assure
adequate intake of essential nutrients (Nivas and Sunde, 1969).
Partition of ingested energy (IE) in the chicken is described
schematically in Fig 1. The terminology and abbreviations are taken
from NRC (1981). Most of the IE which is not digested and absorbed 1S
voided as feces energy (FE). The difference IE - FE is apparent
digestible energy (ADE). The expression "apparent" is used because
feces contain, in addition to the energy of feed residues (F.E), a 1
metabolic fraction (F E) comprising bile, mucosal cells and m
unabsorbed intestinal secretions.
During the process of digestion, gas 1S produced by
microflora. The energy lost as a gas (GE) is usually neglected in
avian balance experiments but in ruminants the loss can be significant
and is treated as a metabolic loss (Scott, Nesheim and Young 1982).
r-__________ I_n_g_e_s_t_e~dl Energy (IE)
Apparent Digestible Energy (ADE)
Fecal Energy (FE) Gaseous Energy (GE)
Fecal Energy of Feed (F.E)
~
Apparent Metabolizable Energy (AME)
Urinary Energy (UE) Metabolic I
Endogenous
I I
Urinary Fecal Energy (F E)
m Urinary Energy (U E)
Energy of Feed (U.E)
~ 1- True Metabolizable Energy (TME)
J e
r---------~ Heat Increment (H.E) ~
Heat of Fermentation (HfE)
8
Heat of Digestion and Absorption (HdE)
I Net Energy for Maintenance (NE )
m
Basal Metabolism (H E) e
Heat of Activity (H.E) J
Net Energy (NE) I
Heat of Thermal Regulation (H E) c
Metabolic Fecal Energy (F E) m
Endogenous Urinary Energy (U E) e
Heat of Product Formation (H E)
r Heat of Waste
Formation and Excretion (H E)
w
I Net Energy for Production (NE r )
Tissue Growth
Fat Accretion
Carbohydrate Storage
Eggs
Semen
Figure 1. Partition of ingested energy
9
A portion of the absorbed energy is excreted in urine without
having been completely catabolized (UiE), mostly as uric acid in
birds. Waring and Shannon (1969) determined that urine of birds fed
soybean diets had a GE content of 12 kcal/g N. They suggested that
ur1ne contains appreciable quantities of energy yielding components
other than uric acid (8.22 kcal/g N). Urinary energy (UE) also
contains an endogenous fraction (U.E) which is the product of tissue 1
catabolism. The difference IE - FE - GE - UE is apparent metabolizable
energy (AME).
Several metabolic functions in the transformation of IE yield
heat increment (H.E). H.E includes heat of digestion and 1 1
absorption, heat of product formation (HrE), heat of microbial
fermentation (HfE), and heat of waste formation and excretion
(H E). H.E is normally considered to be waste but it does w 1
contribute to the maintenance of body temperature in cool environments.
Net energy (NE) is the difference between ME and H.I and 1
compr1ses that portion of IE used either for body maintenance (NE ) m
or for productive purposes (NE). Maintenance energy costs also r
include basal metabolism (H E), heat of activity (H.E) and heat e 1
lost as a result of maintaining body temperature 1n hot or cool
environments (H E). The NE is the energy retained 1n the body or c r
voided as a useful products such as egg and semen (Emmans, 1974).
Use of added fat to increase the energy concentration of
poultry diets is common practice. A number of different sources of
supplemental fat have been used in poultry diets to improve feed
efficiency and body-weight gains; these include the vegetable oils,
10
animal fats, and mixtures of animal and vegetable fats. Biely and
March (1954) found that edible tallow improved both weight gain and
feed utilization when fed to chicks from 1 day to 10 weeks of age. In
the above research, improvements of 6.5% in weight gains and 3.5% in
feed efficiency were recorded. Research by Waibel (1958) on the use of
a stabilized mixture of equal parts of beef and pork fat, reported that
when the mixture comprised 10% of the diet, feed efficiency and body
weight were improved.
Supplementing vegetable oils to turkey diets improved
production; older turkeys (16 to 24 weeks of age) were able to use
rapeseed oil as effectively as soybean or sunflower oil. However,
rapeseed oil had a harmful effect on growth of young turkeys from 0 to
6 weeks of age (Blakely, MacGregor and Hanel, 1965). Rapeseed oil
contains a high concentration of erucic acid which is toxic and thereby
impairs performance. Corn oil has also been used as a supplemental fat
source for growing chicks. Carew and Hill (1964) found that levels of
3.5 to 10% supplemental corn oil were effective in improving the
efficiency of energy metabolism. Diets supplemented with an
animal-vegetable fat blend have been shown to produce positive results
in both weight gain and feed efficiency. The weight gain response
J. varied from .7 to 1.6% improvement per 1% added fat (Sell and Owings,
1980).
A synergistic effect between fats has been reported by a
number of researchers and is normally attributed to improved absorption
of the more saturated fats as a result of the presence of
polyunsaturated fatty acids and phospholipids in the diet. A
11
considerable degree of interaction between blended fats of differing
chemical structure has been observed. This interaction among fats may
be of importance during determinations of their ME. It has been
established that mixing fat containing a high percentage of unsaturated
fatty acids with one with a majority of saturated fatty acids will
improve the absorption and subsequent dietary energy value of the
latter. A similar reaction has been illustrated with individual fatty
acids (Young, 1961). The utilization of palmitic and stearic acids is
enhanced by the addition of oleic and linoleic acids.
Blending an equal mixture of a mostly saturated fat (~.
tallow) and a relatively unsaturated one (~. soybean oil) resulted
in higher ME values than the average of the two individual fat values
(Sibbald and Kramer, 1977). The optimum amount of polyunsaturated fat
needed to improve the dietary energy value of saturated fats was
studied by Lewis and Payne (1966). They suggested that the addition of
only 5% soybean oil relative to tallow (at a total fat inclusion level
of 10% of the diet) improved the mixture utilization by almost 16%. To
quantify the degree of synergism, measurements of the ratio of
unsaturated to saturated fatty acids in a mixture has been used in
studies by Lall and Slinger (1973). They found that the ratio of
2.15:1 (unsaturated:saturated fatty acids) produced optimum energy
values.
Interactions between added fats and the non-fat components of
the basal diet have been shown by Mateos and Sell (1980a). Such
effects have been attributed to added fat decreasing the entire rate of
passage through the gut, thus allowing greater time for digestion and
12
absorption of dietary nutrients. Sibbald, Slinger and Ashton (1961)
reported an increase in the AME of tallow for chic!cs when fed in a
blend with soybean oil. Also, Sibbald and Kramer (1978) found that
tallow true metabolizable ene~gy (TME) varied with the basal diet;
whereas, Dale and Fuller (1981) showed an inverse relationship between
the amount of fat in the basal diet and resulting TME of corn oil.
The existence of mineral ions in the basal diet has been
associated with decreasing the availability of an added fat in poultry
diets due to the formation of soap (Sibbald and Price, 1977). Free
fatty acids are more likely to produce insoluble soaps in vivo.
It has been recommended that the protein level in the basal
diet may affect availability of added fat; higher protein diets have
been reported to support improved absorption of lard (Young, Garrett
and Griffith, 1963) and tallow (Sibbald et al., 1961) compared to
lower protein diets.
Evaluating the synergism between supplemental fat and basal
fat is important in predicting 'the dietary energy value of a
supplemental fat. Dietary energy value attributed to a fat has been
shown to be dependent upon the level at which it is added in the basal
diet (Lesson and Summers, 1976). Thus, inclusion level and basal diet
composition have both been found to influence the ME value obtained for
fats. Sibbald et al. (1961) found values of 6.02 and 7.24 kcal/g,
respectively, for tallow fed at 10 and 20% in a basal diet comprising
24.4% protein, and values of 6.79 and 7.69 kcal/g for the same tallow
fed at 10 and 20% of a 34.0% protein basal diet. Horani and Sell
(1977a) also reported that the major effect of supplemental fat on
13
ration ME occurred when the supplement was utilized at levels of 4-6%
of the diet. However, Fuller and Rendon (1979) determined that level
of fat supplementation had no effect upon its dietary energy value when
measured at 5%, 10% and 20% inclusion levels.
Wiseman and Cole (1983) studied the effect of level of
inclusion (from 0 to 10% in successive 1% increments) of a commercial
fat blend into a synthetic fat-free or commercial basal with 3 week old
broilers. They found that the chemical structure of a fat has a marked
influence upon its ME value and with the substitution method of
determining ME values the results obtained may be influenced by fat
inclusion level, and the nature of the basal. Extrapolation of linear
functions to 100% fat inclusion resulted in AME values for the fat of
6.45 and 6.5 kcal/g when included in the semi-synthetic and commercial
basal diets, respectively.
As for the effect of added fat on the rate of passage,
Mateos, Sell and Eastwood (1982) found that transit time increased
linearly, with adult hens, when levels of fat added into a commercial
basal were increased from 5% to 30% in 5% increments. This observation
may be helpful in understanding the nature of the extra metabolic
effect of fat in poultry diets. By increasing transit time,
supplemental fats may improve digestibility of other dietary
constituents and thereby increase the utilization of dietary energy.
The "extra caloric effect" of dietary fat has been assumed to
be largely if not completely made up of the reduced HI or increased
associative dynamic effect (ADE) of fat (Jensen ~ al., 1970).
This effect was first studied by Forbes and Swift (1944) and resulted
14
from a reduction of the HI or heat loss that occurs when nutrients are
fed in combination, compared with the sum of the HI of individual
nutrients. The largest reduction in heat loss occurred when the
combination of nutrients included fat.
In an experiment with broiler chicks, Carew and Hill (1964)
found that replacement of dietary carbohydrate with corn oil increased
the efficiency of energy utilization. Mateos and Sell (1980a) studied
the effect of inclusion of 4, 8 or 12% yellow grease in
sucrose-containing diets. Results showed that supplemental yellow
grease increased ME of diets containing sucrose more than expected.
Protein and amino acid requirements of 1a:'ing hens are
functions of egg production rate, egg weight, body weight and body
weight gain. If expressed as dietary concentrations rather than
absolute daily intakes, the two additional variables of dietary energy
concentration and environment, both determinants of feed intake, must
be added (Hurwitz et a1., 1978).
Protein requirements for hybrid pullets have been evaluated
to be around 14-15 g/d by Thayer et a1. (1974); while others have
found that around 17 g/d was needed for the optimum performance of
laying hens (Aitken, Dickerson and Gowe, 1973; and Reid, 1976). These
variations in protein requirement can be interpreted on the basis of
dietary essential amino acid levels. A diet containing adequate lysine
and methionine, relatively low protein (13%), was found to be as
effective as diets containing 15, 17 or 18% protein for maintaining egg
production and egg size (Fernandez, Salman and McGinnis, 1973). In a
study of the effectiveness of sulfate on TSAA requirements of laying
15
hens, Reid and Weber (1974) reported that the feeding of a 14% protein
diet comprising .55% TSAA supported maximum egg production.
Daily protein and amino acid requirements of laying hens may
be calculated using a modification of the equation Model B as reported
by Hurwitz and Bornstein (1973), which considers needs for maintenance,
gaLn, egg mass and egg composition. The equation is as follows:
AA = Am w/.85 + (~W)(AT) + %p/100 x EW (62 Ay + 59 Ao + 52 At)
where:
AA = Daily amino acid (mg)
Am = Amino acid needs for maintenance (mg)
W = Body weight (kg)
D"W = Daily body weight change (g)
At = Amino acids in body 'tissue as (%) of N x 6.25
%p = Percent egg production
EW = Egg weight (g)
Ay = Amino acids in yolk as (%) of N x 6.25
Ao = Amino acids in ovalbumen as (%) of N x 6.25
The values for Am, At, Ay and Ao are a fraction of the respective amLno
acid in protein for maintenance, tissue, yolk and ovamucoid,
respectively. The values for Am were 100% of the maintenance needs
suggested by Leveille, Shapiro and Fisher (1960). The advantage of
using this model is to calculate the amino acid requirements of laying
hens for any combination of the three variables that make up the total
requirements. The model could be used to calculate the amino acid
requirements for large birds such as the turkey or small birds such as
quai 1.
16
One of the most difficult problems facing the poultry
industry is reduced performance during adverse hot weather conditions.
Feed intakes are normally reduced and the rate of gain and egg output
decline with high temperature.
Adams et al. (1962a) examined the use of increased
dietary energy and protein levels to overcome the adverse effects of
high environmental temperature on the performance of chicks. From 4 to
8 weeks of age birds were exposed to temperatures of 21 or 32°C.
Energy levels were increased by 2% by substitution of a soybean
meal-fish soluble blend for corn. Increasing the energy level of the
ration improved growth rate and efficiency of feed utilization at both
temperatures. Increasing the vitamin, mineral or protein content of
the ration failed to improve growth at either temperature.
Adams et~. (1962b) also investigated the total sulfur
am~no acid (TSAA) needs of broiler chicks from 4 to 8 weeks of age
maintained at 21 or 29°C. The chicks were fed diets ranging from .4
to .9% TSAA. They found that the amino acid needs of the chick,
expressed as dietary percentages, were higher at the higher
temperature.
The effects of differences in energy input both from diet and
from environmental temperature on the response of chicks to diets
containing different levels of lysine, were studied by March and Biely
(1972). Performance was depressed when the environmental temperature
and/or the dietary energy level was increased.
McNaughton et al. (1978) examined the influence of 15.6
and 29.4°C environmental temperatures on 2- to 4-week broiler
17
requirements. Dietary lysine levels of between .80 and 1.15% in .05%
increments were fed. ~hey found that feed was more efficiently
utilized by 4-week old cockerels fed either 1.10% dietary lysine in the
15.6°C environment or .95% dietary lysine in the 29.4°C environment.
It is usually suggested that protein and amino acid levels for laying
hens be increased at higher environmental temperature to overcome the
reduction in feed intake. Valencia, Maiorino and Reid (1980) reported
that increasing the dietary protein level of layer diets resulted in an
increase in egg weight and total daily egg production. Egg weights
were significantly higher at lower environmental temperature and with
the feeding of the higher protein diets.
The concept of the energy:protein ratio was developed as a
simple means to balance the protein and energy contents of broiler and
hen diets (Matterson ~ al., 1955 and Donaldson et al., 1955).
It was noticed that chicks fed high energy diets needed higher dietary
protein contents for maximum growth than those fed on low energy diets.
In addition, carcass fat content is highly correlated with the dietary
energy:protein ratio (Donaldson, Combs and Romoser, 1956). Carcass
water decreased and carcaSs lipid increased as the ME:protein ratio
increased from 13.9 to 17.89 kcal/g (Pesti, 1982). He concluded that
carcaSS lipid of 3-week old male chicks can be manipulated within 10 to
20 g/kg with diets producing good gain.
Hill and Dansky (1950) observed that growth rate was
decreased in comparison with a high protein level when a high energy -
low protein ration was fed, but that growth was restored when the
energy level was lowered. Sunde (1956) showed that a ration high in
protein and low ~n energy reduced growth and feed efficiency and that
the addition of energy to this ration improved both growth and feed
efficiency. Although many studies with poultry have suggested the
usefulness of energy:protein ratios in formulation (Hochreich et
~., 1958), more recent practices express the amino acid requirements
of hens in relation to the energy content of the diet, ~e., percent
of am~no acid per Mcal of ME.
18
As early as 1955, Baldini and Rosenberg showed that
methionine requirement of chicks increased as the energy level of the
ration was increased. Guillaume and Summers (1970) have studied the
effects of amino acid balance on energy utilization and showed that an
improvement in ME utilization occurred due to improved amino acid
balance in the diet, and a reduction in HI was observed due to the
improved am~no acid balance. On the other hand, HI increased when
alanine, asparagine and phenylalanine were fed in excessive amounts
(Burlacu, 1969). Recently, Reid and Maiorino (1984) studied the
effects of TSAA deficiency and methionine toxicity on energy
utilization of laying hens housed at 15.6 and 32.2°C. They found that
feed intake and ME intake of nontoxic TSAA diets decreased
significantly at 32.2°C, whereas significant decrease occurred at both
temperatures with toxic diet. Energy balance and efficiency of
conversion of dietary ME to NE increased at both temperatures as
dietary TSAA increased up to .51%. However, maintenance energy
requirements remained unchanged at .51% TSAA level. Overall, the
results of this study recommended that optimum energy utilization
produced by intakes of 609 mg TSAA/d and 17.3 g protein.
CHAPTER 3
EFFECTS OF ADDED TALLOW ON DIETARY NUTRIENT UTILIZATION
Introduction
Addition of fat to poultry diets increases the metabolizable
energy (ME) more than anticipated from the additivity of the ME's of
the particular ingredients (Wilder, Cullen and Rasmussen, 1959; Jensen
et al., 1970; Horani and Sell, 1977b; Sell, Tenesaca and Bales,
1979; Mateos and Sell, 1980a). For example, ME values of yellow grease
were found to be 8.92 to 9.53 kcal/g which are higher than anticipated
and even exceeded the gross energy (GE) (Wilder et al., 1959).
This effect could be due to a positive interaction between fatty acids
supplied by the added fat and fatty acids present in the basal diet or
carrier material. However, there is a possibility that supplemental
fat improves the digestion and absorption of other nutrients, thus
elevating the ME of diets (Sibbald ~ al., 1961; Sibbald, 1978;
Sibbald and Kramer, 1978; Mateos and Sell, 1980b; Dale and Fuller,
1981).
Gomez and Polin (1974), Sibbald and Kramer (1978), and Mateos
and Sell (1981) reported that interactions between supplemental fat and
non-lipid dietary constituents improved utilization of dietary energy.
Moreover, Horani and Sell (1977b) found that the effects of
supplemental tallow depended upon the composition of the laying hen
diet. Changes in ration ME caused by fat, measured experimentally,
19
20
exceeded that anticipated on the basis of calculated ME values of the
ration. Kalmbach and Potter (1959) and Sell and Mateos (1981) found ME
values for yellow gr'ease of 8.50 and 8.21 kcal/g in corn and wheat
based diets. It is thought that supplemental fats increase the
utilization of other dietary components by decreasing the rates of feed
passage, thereby enhancing the ME of diets.
There have been several studies since the early 1950's that
document the beneficial effects of supplemental fats in poultry rations
(Yacowitz, 1953; Lillie et al., 1952; March and Biely, 1963; Reid
and Weber, 1975). Improvements in efficiency of feed utilization were
noticed consistently, and frequently productive performance was
enhanced.
The objectives of this experiment were to study the
usefulness of animal tallow in laying hen rations, and to determine the
effect of added fat on the energy and nutrient utilization of the
rations fed.
Experimental Procedure
One hundred and ninety-two SC White Leghorn hens (Shaver
288A) of similar age and weight were used in this study. Each
experimental diet was fed to 32 birds (4 replications of 8 birds),
housed 4 birds per cage, for nine 28-day periods.
The basal diet shown in Table 1 was formulated by linear
programming techniques to meet the nutri~nt levels recommended by the
National Research Council (NRC, 1984) for the laying hen. The
experimental diets consisted of six levels of animal tallow (0, 2, 4,
Table 1. Composition of basal diet (Experiment 1)
Ingredient %
Ground milo Soybean meal (48.5%) Dehy. alfalfa meal DL-methionine Ground limestone Dicalcium phosphate Salt 1 Vitamin mix Pr-9
. l' 2 Trace m1nera m1X Chromium oxide
Total
Nutrient3
Protein, % ME, kcal/g Met + Cys, % Lysine, % Calcium, % Avail. Phosphorus, %
62.05 21.14 5.00
.13 8.55 1.48
.35 1. 00
.10
.20
100.00
16.98 2.69
.63
.87 3.80
.38
ISupplied the following per kg of diet: 3,966 IU vitamin A, 615 ICU vitamin D3 ,
1.78 mg riboflavin, 11.2 mg niacin, 4.5 mg calcium pantothenate, 5.3 pg vitamin B12 , 2.2 IU d-alpha tocopheryl acetate,
.88 mg menadione sodium bisulfite, 175 mg choline chloride, and 50 mg ethoxyquin
2Supplied the following (ppm): 20 Fe, 60 Zn, 60 Mn, 4 Cu, and 1 Mo
3Calculated analysis
21
22
6, 8 and 10%) added to the basal diet at the expense of the total
percentage to provide a range of ME levels. Fatty acid composition of
the animal tallow used in this study as determined by gas
chromatography are shown in Table 2. Hens were supplied feed and water
ad libitum. Egg production, body weight, egg weight and feed
consumption data were recorded throughout the experimental period and
summarized every 28 days.
Feed and excreta samples collected during periods 2, 4, 6,
and 8 were analysed for GE, protein, amino acids, starch, fat and fatty
acids. GE was determined using a Parr adiabatic oxygen bomb
calorimeter. Nitrogen determinations were carried out by the
micro-Kjeldahl method and protein estimated as 6.25 x %N (ADAC, 1980).
Feed and excreta samples were hydrolyzed for determination of amino
acids in 6N HCI in the presence of mercaptoacetic acid sodium salt to
preserve methionine. Following hydrolysis in an autoclave for 16-18
hours at 121°C (15 psi) samples were evaporated to dryness under
vacuum and dissolved in 10 ml sodium citrate buffer (pH 2.2).
Fluorescent o-phthalaldehyde amino acid derivatives were separated
using a Spectra-Physics SP8000B high pressure liquid chromatograph
(HPLC) with a 3 p RP-18 column (Jones, Paabo and Stein, 1981).
Starch analyses were carried out by the anthrone method described by
Clegg (1965). Chloroform:methanol (2:1 v/v) extraction was employed to
determine total fat content. Fatty acid methyl esters were prepared
using a boron trifluoride:methanol reagent (ADCS, 1972) and were
assayed using a Shimadzu GC-8 gas chromatograph equipped with a
Spectra-Physics 4270 integrator and a 10% DEGS column (Ackman, 1969).
T bl 2 'd" f 1 a e . Fatty ac~ compos~t~on 0 tallow
Fatty Acid 2 % of Sample
14:0 4.47 14:1 1. 37 14:2 .64 16:0 29.04 16:1 4.29 16:2 .54 16:3 .93 17:0 .59 18:0 11. 95 18: 1 43.87 18:2 2.31 20:0 Trace
Saturates 46.05 Monoenes 49.53 Dienes 3.49 Trienes .93
IValencia et al., 1980
2Number of carbon atoms:number of double bonds
3Relative amounts of fatty acids in weight percent of saponifiable fraction
23
3
24
The analytical values obtained were used to calculate
nutrient retentions using the inert marker (chromium oxide) technique.
Analyses of variance were accomplished to determine statistical
significance, and the means were separated at P<.05 using LSD (Iman and
Conover, 1983). Regression analyses were run to evaluate the effects
of added tallow on the utilization of dietary nutrients and to estimate
the ME of the added tallow.
Results and Discussion
Egg production and egg mass were not significantly affected
by tallow level (Table 3). Egg weight was not affected by tallow
supplementation up to 6% and decreased as the fat level increased to 8
or 10%. Average hen-day feed consumption decreased from 110.7 to 98.2
g) as the level of added fat increased from 0 to 10%, respectively).
Feed conversion was significantly improved from 1.67 for the
unsupplemented diet to 1.55 kg/doz at the 6% tallow level and was not
significantly affected by the higher tallow levels fed. These results
are in agreement with those reported by Horani and Sell (1977a,b) and
Jackson, Kirkpatrick and Fulton (1969) in that addition of fat to
laying hen diets resulted in significant improvements in feed
conversion without adversely affecting other production
characteristics. Reid (1984) summarized the effects of tallow
supplementation on laying hen perfor.mance and found that optimum tallow
levels for egg mass, production rate and feed converS1on were 4.93,
5.06 and 5.78%, respectively. Body weights were significantly higher
Table 3. Tallow supplementation and laying hen performance (Experiment 1)
Criteria
Egg production (%)
Egg Mass (g/d)
Egg Wt. (g)
Supplemental Tallow (%)
o 2 4 6 B
BO.3 BO.2 7B.l B1. 2 79.1
47.2 46.9 46.2 4B.2 46.4
s9.0abc sB.6c
25
10
7B.s
45.9
Feed Conversion (kg/dz) 1.67 a 1.64a 1.62ab 1.ss c 1.s7bc 1.s2c
Body Wt. (kg) 1.Bl c 1.BBb 1. 91ab 1.9sa 1.93a 1.B9b
Body Wt. Chg. (g/hen/d) .B6 1.07 1.27 1.2B 1.37 1.21
Feed Intake (g/hen/d) 110.7a 10B.lb 104.0c 104.3c 101.2d 9B.2e
Protein Intake (g/hen/d) IB.B a IB.Ob 17.0c 16.7c ls.Bd 15.0e
TSAA Intake (mg/hen/d) 696.6 a 666.4b 627.9c 616.B c 5Bs.4d 556.1 e
Lysine Intake (mg/hen/d) 959.1 a 917.5 b B64.5 c B49.2c B06.0d 765.7 e
a-e ' h' h . Means W1t 1n a row not aV1ng common letter superscripts are significantly different (P<.05)
for all birds fed the tallow supplemented diets 1n compar1son with
those fed the basal diet (Table 3).
26
The effects of tallow on dietary nutrient intakes are shown
in Table 3. Protein intake levels dropped significantly as tallow
levels increased in the diet due to reductions in feed intake. The
highest level of tallow (10%) resulted in an average protein intake
which was slightly below that recommended (15.95 g/d) by the NRC
(1984). Total sulfur-containing amino acid (TSAA) intakes decrea~ed to
below the 600 mg/d requirement as tallow levels increased to 8 and 10%,
dropping from 696.6 mg/d for the basal diet to 556.1 mg at the 10%
tallow level. Lysine (Lys) intakes also decreased from 959.1 to 765.7
mg/d as tallow levels increased from 0 to 10%, but these were all in
excess of the NRC (1984) recommended amounts.
ME consumption was significantly improved with tallow levels
of 6% and above (Table 4). ME intake increased from 305.1 to 322.4'
kcal/hen/d with 6% tallow. There was no further improvement in ME
intake noticed at the 8 or 10% tallow levels. Energy balance,
calculated from egg mass (1.6 kcal/g) and body weight change (5.0
kcal/g) data, showed a significant improvement with 6% added tallow
(Table 4). In view of the lack of a statistically significant response
1n egg mass, the increases in energy balance were due mostly to changes
in body weight as a result of increased ME intakes associated with
tallow.
Gross energetic efficiency, the ratio of energy balance to ME
intake, was not significantly affected by tallow level. Net energetic
efficiency which represents the percentage conversion of ME intake
27
Table 4. Effect of dietary tallow level on energy utilization in laying hens (Experiment 1)
Supplemental Tallow (%)
o 2 4 6 8 10
Dietary ME (kcal/g) 2.76d 2.79d 2.93c 3.09b 3.16ab 3.24a
ME Intake (kcal/d) 305.1 b 303.0b 305.2b 322.4a 320.5 a 319.9a
Energy Balance (kcal/d) 79.8 80.4 80.2 83.5 81.0 79.6
Dietary NE (kcal/g) 2.00bc 2.09b 2.21 ab 2.27 a 2.30a 2.30 a
Gross Energetic Eff. (%) 26.3 26.5 26.2 25.9 25.2 24.8
Maint. Energy (kcal/d)
ME Intake above Maint. (kcal/d) 110.2 106.7 106.4 113.1 110.5 111.4
Heat Increment + Activity a 85.3 (kcal/d)
Net Energetic Eff. (%)
a-d . h· h . 1 . Means w~t ~n a row not av~ng common etter superscr~pts are significantly different (P<.05)
Regression of Energy Balance on ME Intake above Maintenance:
Energy Balance = .757 (ME Intake above Maint.) - 10.19 (r
Regression of Dietary NE on % Tallow
Dietary NE .0312 (% Tallow) + 2.039
Tallow NE 5.17 kcal/g
.954 )
above maintenance to net energy (NE), increased significantly with 2
and 4% added tallow, but was not significantly different from the
unsupplemented diet for higher tallow levels. Regression of energy
balance on ME intake above maintenance produced a significant (P<.05)
correlation coefficient (r = .954) with a regression coefficient of
.757, indicating an average net energetic efficiency of 75.7% for the
hens in this study.
28
Maintenance energy needs, calculated according to Emmans'
(1974) equation, increased as the tallow level exceeded 4% due to
increases in body weight. Dietary NE increased from 2.0 to 2.3 kcal/g
feed and determined dietary ME improved from 2.76 to 3.24 kcal/g as
tallow levels increased from 0 to 10%. Regression of NE on tallow
level yielded a predicted NE value for tallow of 5.17 kcal/g,
representing 64.2% of the estimated ME (8.05 kcal/g) of tallow in this
study (Table 4). Heat increment (HI) decreased significantly at the 2
and 4% tallow levels and increased with the higher tallow levels due,
apparently, to the TSAA deficiency since it has been shown that poor
amino acid balance produces increases in HI.
Two factors appear to have affected performance in this
study. The first was associated with the increased ME intakes with
supplemental tallow which became significant at the 6% tallow level and
produced a higher ME intake above maintenance and slightly higher egg
production and egg mass. The second factor was found in the
improvements in net energetic efficiency with either 2 or 4% added
tallow and produced slight, but non-significant, increases in energy
balance with slightly lower ME intakes above maintenance.
The effect of age and temperature on hen performance are
summarized in Table 5. As expected, egg production and egg mass
decreased significantly from 90.7% and 49.1 g/hen/d to 65% and 38.8
g/hen/d at the end of the experiment. Egg production, after the peak
in production, was significantly depressed during the January period
and declined slowly thereafter. Body weight change also became
negative during this period.
29
Feed consumption declined from about 112 g feed/d during the
cold periods to about 95 gld during the hot periods (June and July).
These results are consistent with those of Davis et al. (1972),
Reid and Weber (1973) and Emmans (1974) in that an inverse relationship
between high environmental temperature and feed intake occurs in laying
hens. The decline in feed intake with an increase in environmental
temperature results in less energy available for productive purposes.
The decrease in feed intake could be explained by the decrease in
maintenance energy requirements and lower egg production rates during
hot periods. Maintenance energy requirements of the hens during hot
periods were 14% less than those in cold periods, while ME intake
decreased by 21%.
Net energetic efficiency was adversely affected by
temperature during the experiment. Net energetic efficiency was
significantly reduced during the January to April periods and was
significantly higher during the beginning and ending periods of the
study. These periods of lowered net efficiency also corresponded to
the periods of highest maintenance needs. Maintenance energy during
these periods ranged from 212.1 to 222.4 kcal/hen/d, while values of
Table 5. Effects of environmental temperatu~e and age on laying hen performance (Expe~iment 1)
Criteria
Egg Production (%)
Egg Mass (g/d)
Egg Weight (g)
Feed Conversion (kg/dz)
Body Weight (kg)
Body Wt. Chg. (g/hen/d)
Feed Intake (g/hen/d)
Protein Intake (g/hen/d)
TSAA Intake (mg/hen/d)
Lysine Intake (mg/hen/d)
HE Intake (kcal/d)
Energy Balance (kcal/d)
Gross Energetic Eff. (%)
Haint. Energy (kcal/d)
Net Energetic Eff. (%)
T REA THE N T PER I 0 D S
1 2 3 4 S 6 7 8 9 Nov. Dec. Jan. Feb. Mar. Apr. Hay June July
11.7°C l2.2°C 10.3°C II.8°c IS.7°C 18.2°C 22.3°c 28.I o c 29.7°C
90.7a 88.8a 84.1b 83.Sb 80.1bc 77.7cd 7S.1de 6S.0f 7l.1 e
49.1 a SO.Oa 48.4a SO.Oa 48.Sa 47.6ab 45.2bc 38.8d 43.7c
54.2g 56.3f 57.5e 59.9cd 60.6bc 6l.2ab 60.I cd 59.6d 6l.4a
I.3l e 1.45d 1.54c 1.63b 1.68b 1.69b 1.62b 1.80a 1.63b
1.77e I.90cd
1.87d 1.87d 1.90cd 1.93bc 2.00a 2.03a I.99ab
2.80b 4.69a _.8gef _.03de 1.08cd l.08cd 2.5I bc .99cd -l.65 f
96.6de 95.5e
l5.6de 15.4e
99.0cd 107.0b 107.7b
16.0cd l7.3b l7.4b
112.5a 112.0a 108.8b 100.8c
18.2a l8.1 a l7.6b l6.3c
592.I cd 640.Ib 644.5b 673.4a 670.4a 65l.3b 602.7c 577.7de 571.7e
8lS.2cd 881.3b 887.4b 927.2a 923.0a 896.7b 829.8c 795.3de 787.I e
301.0d 324.9c 327.3bc 336.6a 334.9ab 327.7abc 304.2b 280.3e 277.2e
92.6b 103.4a 73.0de 79.9cd 83.1c 8I.5cd 84.8bc 67.0ef 61.6f
30.8a 31.8a 22.4cd 23.8cd 24.8cd 24.9c 27.9b 23.8cd 22.2d
179.9d
19I.6c 222.4a
220.7ab
214.7ab
212.1b
195.4c 194.1c
19S.8c
76.6a 77.la 69.Ib 68.5b 69.2
b 70.4
b 77.3a 77.34
HE Intake> Haint. (kcal/d) 121.0b l33.3a 104.9d 1I6.0bc 120.2b lI5.6bc 10S.8cd S6.2e
7S.4a
8l.5e
68.5b HI + Activity (kcal/d) 7l.0b 74.5b 101.64 106.6a 103.7a 97.4a 69.6
b 63.9b
a-fMeans within 4 row not having common letter superscripts are significantly different (P<.05) w o
179.9 to 194.1 kcal/d were observed during the other periods of the
study. Waring and Brown (1965, 1967), Shannon and Brown (1969) and
Valencia et~. (1980) have reported similar results.
31
Body weight increased significantly from 1.77 to 1.99 kg and
egg weight increased from 54.2 to 61.4 g as the birds became older
(Table 5). Poorest feed conversion (1.8 kg/doz) was obtained when the
temperature was around 28°C. Protein intake decreased in hot periods
as a result of low feed intake. Accordingly, TSAA and Lys intakes
decreased in hot periods.
Effects of bird age on tallow utilization are shown in Table
6. Tallow ME (kcal/g) obtained from linear regression analyses
decreased significantly from 8.88 to 7.32 kcal/g as the birds became
older. Percentage of tallow digestibility also decreased significantly
from 87.1 to 73.3 at the end of the experimental period. Tallow ME
(kcal/g) obtained from digestibility data also decreased significantly
from 8.19 to 6.89 kcal/g with age. The lower ME values for tallow
obtained using digestibility data indicate some effect of added tallow
on the digestibilities of nutrients in the basal diet.
The differences ~n ME values obtained with the two methods
led to investigations of the utilization of other nutrients in the
basal diet (Table 7). No improvement in starch retention was observed
due to tallow supplementation or age (Table 7). Starch retentions were
uniformly high, ranging from 93.4 to 95.29%.
Fat retention, however, was increased significantly from
55.7% for the basal diet to around 76% when 10% tallow was fed (Table
7). Maximum fat retention occurred with 10% added tallow. The
32
Table 6. Effect of laying hen age on ME of tallow (Experiment 1)
Periods (Age)
2 4 6 8 Means
Tallow ME (kcal!g) 8.88a 8.45 b 7.70c 7.32d 8.09 (Regression)
Tallow Dig. (%) 87.1 a 84.3b 79.1 c 73.3d 81. 0
Tallow ME (kcal!g) 8.19a 7.92b "7.43c 6.89d 7.61 (Digestibility)
a~ ., h . Means w~th~n a row not av~ng common letter superscripts are significantly different (P(.05)
Table 7. Effect of tallow on nutrient utilization (Experiment 1)
Apparent Retention (%) Diet
Fat Starch Protein
Basal Diet 55. 71 b 95.29 20.80
+ 2% Tallow 71. 09a 94.93 12.76
+ 4% Tallow 71. 64a 94.23 25.31
+ 6% Tallow 73.12a 94.42 26.86
+ 8% Tallow 75.22a 94.09 24.50
+ 10% Tallow 75.99a 93.94 29.28
a_bMeans wi ~hin a column not having common letter superscr~pts are significantly different (P(.05 )
33
significant improvements obtained with tallow supplementation suggest
that the increased ME values calculated from calorimetry data were due
partially to improvements in fat retention from the basal diet or to
the well documented synergistic effect of fats.
Protein retention increased from 20.8% for the basal diet to
around 30% with 10% added tallow. Protein retention improved as the
amount of ME derived from tallow was increased (Table 7). This may
also partially explain the differences in the ME of tallow between
values based on calorimetry and those derived from digestibility data
(Table 6).
The effects of tallow supplementation on amino acid
retentions were quite variable, and thus no significant differences 1n
am1no acid retentions were obtained in this study (Table 8).
Supplemental tallow effects on fatty acid retentions are
presented in Table 9. Only the total saturated fatty acids were not
significantly increased due to fat supplementation. These data suggest
that the feeding of tallow improved utilization of some of the fatty
acids in the basal diet. Fat retention from the basal diet was quite
low at only 55.71%. These results are inconsistent with Al-Hozab's
(1985) results in that the retentions of saturated fatty acids were
significantly improved with 6% tallow in some feedstuffs. Both mono
and poly-unsaturated fatty acid retentions were significantly increased
with each tallow increment up to 8%. Maximum oleic (CI8:l) and
linoleic (Cl8:2) acid retentions also occurred with 8% tallow. Tallow
supplementation up to 8% decreased stearic (CI8:0) acid retention.
34
Tab Ie 8. Effect of tallow supplementation on average amino acid retention by laying hens (Experiment 1)
" "d 1 Supplemental Tallow (%)
Aml.no Acl. s 0 2 4 6 8 10
-------------------- (% ) --------------------Arginine 94.30 92.22 91.44 93.43 90.19 92.05
Lysine 68.24 69.47 75.05 78.62 63.54 73.90
Methionine 91.86 87.40 90.60 89.87 89.26 87.45
Cystine 59.22 77.85 56.19 -0.81 31.39 71.80
Phenylalanine 71.94 69.86 79.04 77 .41 80.40 80.39
Tyrosine 92.14 89.41 90.16 91.61 88.39 89.51
Valine 89.62 86.10 87.25 88.75 87.23 86.76
Leucine 91.47 89.00 89.06 78.69 89.73 89.45
Isoleucine 88.84 90.37 87.65 88.78 86.80 87.03
Threonine 86.82 83.34 84.30 85.88 83.46 83.54
Histidine 91.95 89.36 89.35 92.00 88.09 89.22
1 Means of periods 2, 4, 6 and 8
35
Table 9. Effect of tallow supplementation on average fatty acid retention by laying hens (Experiment 1)
'd 1 Supplemental Tallow (%)
Fatty Acl. s 0 2 4 6 8 10
-------------------- (%) ---------------------C16:0 57.80 58.99 64.64 62.41 60.92 64.12
C18:0 52.50 67.65 51.12 46.42 38.56 40.25
C18:1 49.73d 76.62 c 80.32bc 85.34ab 89.26 a 88.68a
C18:2 60.67c 81. 54ab 74.37ab 79.00ab 89.06 a 88.42a
C18:3 70.66c 85.22ab 78.18bc 77.99bc 85. 94ab 86.53a
Saturated 51.84 59.83 61.56 58.58 55.03 58.07
Mono-unsaturated 50.25d 76.29c 81.08bc 85.79ab 89.36 a 88.90 a
Poly-unsaturated 60.15 c 79.88ab 74.43b 78.87ab 88.08a 87.87 a
Total fat 55.71 b 7l.09a 71.64 a 73.12 a 75.22 a 75.99 a
1 Means of periods 2, 4, 6 and 8
a-d , h' h . . Means Wl.t l.n a row not aVl.ng common letter superscrl.pts are significantly different (P<.05)
36
Increased ME levels in laying hen diets resulted in
significantly higher body weights for all birds fed tallow supplemented
diets. An inverse relationship was found between body weight and egg
production by the end of the production periods. Younger hens utilized
fat more efficiently than those at the end of the laying cycle. Also,
at the end of the laying cycle fat deposition is favored over egg
production when fat level or the ratio of energy to protein increases
in the diet. Supplementing fat up to 8 or 10% resulted in low protein,
TSAA and Lys intakes. Thus, it 1S recommended that dietary protein,
TSAA and Lys levels be increased with high fat levels.
Summary
This experiment was conducted to evaluate the effects of
added tallow on nutrient utilization in laying hens. Tallow increased
fat retention significantly while both protein and starch retentions
were only marginally affected by tallow. Egg production and egg mass
were not significantly affected by dietary tallow level. Body weight,
and feed conversion reached maximum levels with a tallow level of 6%
and decreased as tallow levels increased above 6%. Feed intake
remained relatively constant at about 104 gld through tallow levels of
4 and 6%, and decreased to about 98 gld with the 10% tallow diet. ME
consumption and energy balance increased with tallow levels up to 6%.
Higher tallow ME values were obtained from calorimetry data
than from digestibility measurements due to the beneficial effects of
tallow on the digestibilities of fat and protein in the basal diet.
37
Tallow ME obtained from regression analyses and digestibility
decreased significantly with age of bird. The decreases in the ME of
tallow obtained as the hens became older suggests that the best use of
tallow would be in the diet of young birds during the early stages of
production.
CHAPTER 4
EFFECTS OF TALLOW SUPPLEMENTATION
IN MINIMAL AMINO ACID DIETS
Introduction
One of the more severe problems facing the poultry industry
is reduced performance during adverse hot weather conditions when feed
intakes are normally reduced and the rate of gain or egg output decline
due to reduced metabolizable energy (ME) intakes above maintenance
available for production. A number of dietary manipulations are often
made at these times in attempts to overcome the reduction in hen
performance. One of the most common practices is the adjustment of
dietary protein and amino acid levels. A newer method of adjusting
diets involves formulation to amino acid requirements without regard to
total dietary protein level. Diets of this type are lower in total
protein, but still meet the essential amino acid needs of the animal.
Such diets should result in lower heat production than those formulated
along more traditional lines.
Brown, Waring and Squance (1965) demonstrated that the
optimum calorie:protein ratio for egg production, expressed as
kcal/kg:percent crude protein, was in the region of 170:1. They
concluded that when designing high-energy diets for layers an attempt
should be made to keep the calorie:protein ratio close to ~his figure.
However, more recent studies concerning amino acid requirements of
38
laying hens express the am~no acid requirement in relation to the
energy content of the diet.
39
Adams and associates (1962a) examined the use of increased
dietary energy and protein levels to overcome the adverse effect of
high environmental temperatures on the performance of chicks.
Increased dietary energy level improved the rate of gain regardless of
environmental temperature, while increased protein failed to overcome
the adverse effects of increased environmental temperature.
Reid and Maiorino (1984) examined the effects of total
sulfur-containing amino acids (TSAA) levels on energy utilization of
laying hens as influenced by environmental temperature. Hens were
maintained at 15.6 and 32.2°C and fed diets containing .47, .49, .51
and 3.47% TSAA. Maintenance ME requirements were found to be the same
at each temperature for diets containing .51% TSAA. A level of .50%
TSAA in the diet was adequate to support optimum energy'balance in
laying hens.
Protein requirements for hybrid pullets have been evaluated
to be around 14-15 gld by Thayer et~. (1974); while others have
found that around 17 gld was needed for optimum performance of laying
hens (Aitken ~ al., 1973; Reid, 1976). These variations in
protein requirement can be interpreted on the basis of dietary
essential amino acid levels. A diet containing adequate lysine (Lys)
and methionine (Met), but relatively low (13%) protein, was found to be
as effective as diets containing 15, 17 or 18% protein for maintaining
egg production and size (Fernandez ~ al., 1973).
40
Reid (1984) studied the interaction between Lys and added
tallow. Supplemental tallow levels of 0, 2 and 4% were fed with
dietary Lys ranging from .6 to .84%. Best egg production was obtained
when the Lys level in the diet was .75% or above.
This experiment was conducted to evaluate the effects of
added tallow in diets containing minimal amounts of protein, but
designed to meet the essential amino acid needs ·of the laying hen.
Experimental Procedure
Three hundred and eighty-four White Leghorn hens (Shaver
288A) of similar age and weight were divided into 16 groups at 26 weeks
of age. Each experimental diet was fed to 24 birds (3 replications of
8 birds/treatment) in each of two houses for ten 28-day periods. Hens
were housed four birds/cage in either a conventional house with open
sides (House 10) or in an insulated, evaporatively cooled house (House
11). Temperature means during the experiment are shown in Table 10.
During the initial seven months of the study temperatures in the
insulated house (House 11) were higher than those in the conventional
cage house (House 10). With the onset of hot weather, the evaporative
cooling in House 11 resulted in temperatures which were around 2°C
cooler than House 10.
Experimental diet compositions are shown in Table 11. The
first four experimental diets were formulated by a least cost linear
program. Diet 1 was designed to satisfy both protein (15%) and
essential amino acid requirements of the laying hen according to the
National Research Council (NRC, 1984). Diet 2 was formulated to
41
Table 10. Temperature means during experimental periods (Experimen t 2)
House 101 House 112 Periods
°c of °c of
1. Nov. 11.7 53.1 17.9 64.2 2. Dec. 12.2 54.0 17.8 64.0 3. Jan. 10.3 50.5 16.9 62.4 4. Feb. 11.8 53.2 17.7 63.9 5. Mar. 15.7 60.3 20.5 69.0 6. Apr. 18.2 64.8 21.3 70.3 7. May 22.3 72.1 24.0 75.2 8. June 28.1 82.6 25.9 78.6 9. July 29.7 85.5 27.0 80.6
10. Aug. 29.9 85.8 27.0 80.6
Means 19.0 66.2 21.6 70.9
1 House 10 - conventional system
2House 11 - evaporated system
Table 11. Composition of experimental diets (Experiment 2)
Ingredient
Ground milo Soybean meal Dehy. alfalfa meal Ground limestone Dicalcium phosphate DL-Methionine
S~lt. . 1 V 1. tam1.n m1.X T . I· 2 race m1.nera m1.X Diet 1 Diet 2 Diet 3 Diet 4 Tallow
1
66.66 16.20 5.00 9.02 1.61
.06
.35 1.00
.10
Calculated Nutrient Composition
Protein, % ME, kcal/g Met + Cys, % Lysine, % Calcium, % Avail. phosphorus, %
15.00 2.73
.50
.72 4.00
.39
2
70.04 12.74 5.00 9.00 1.67
.10
.35 1.00
.10
13.62 2.75
.50
.62 4.00
.40
3
66.54 16.22 5.00 9.02 1.61
.16
.35 1.00
.10
15.00 2.72
.60
.72 4.00
.40
Diet Number
4
61.68 21.24 5.00 9.05 1.51
.07
.35 1.00
.10
17.00 2.68
.57
.87 4.00
.38
5
97.00
3.00
14.55 2.89
.49
.70 3.88
.38
6
97.00
3.00
13.21 2.91
.49
.60 3.88
.39
7
97.00
3.00
14.55 2.88
.58
.70 3.88
.39
8
97.00 3.00
16.49 2.84
.55
.84 3.88
.37
Isupplied the following per kg of diet: 3,966 IU vitamin A, 615 ICU vitamin D3
, 1.78 mg riboflavin, 11.2 mg niacin, 4.5 mg calcium pantothenate, 5.3 pg vitamin B12 , 2.2 IU d-alpha tocopheryl acetate, .88 mg menadione sodium bisulfite, 175 mg chol1.ne chloride and 50 mg ethoxyquin
2supplied the following (ppm): 20 Fe, 60 Zn, 60 Mn, 4 CU and 1 Mo .po N
satisfy the essential amino acids at a lower protein level (13.6%).
Diet 3 was the same as Diet 1 with additional Met. Diet 4 was
formulated at 17% protein to provide a high protein level (Table 12).
Each of diet was supplemented with 3% tallow to provide the eight
experimental diets fed in each of the two houses used in the study.
Feed and tap water were supplied ad libitum.
43
Egg production, body weight, egg weight and feed consumption
data were recorded and summarized every 28 days throughout the
experiment. Feed and excreta samples collected during the second
experimental period were analyzed as described for the first experiment
and nutrient retentions were calculated using the inert marker
(chromium oxide) technique. Statistical significance was determined by
analyses of variance and the means separated at P<.05 using LSD (Iman
and Conover, 1983).
Results and Discussion
Significantly higher egg production and egg mass were
obtained in the insulated and cooled house (House 11) in comparison
with those obtained in the open conventional cage house (House 10)
(Table 13). The insulated house was warmer in the cooler months of the
study and cooler during the hotter periods, thus providing a more
uniform temperature throughout the experiment.
In the conventional cage house (House 10), the NRC basal diet
(Diet 1) supported an egg production rate of 73.9% (Table 13).
Reducing the total protein level to 13.6% (Diet 2) resulted in a
significant decrease in egg production to 69.5%. Diet 3, with a higher
Table 12. Tallow, protein and amino acid composition of experimental diets (Experiment 2)
Dietary Treatment
1. Basal NRC Diet 2. NRC-AA Restricted 3. Basal NRC + .1% Met 4. 17% Protein Diet
5. Basal NRC Diet 6. NRC-AA Restricted 7. Basal NRC + .1% Met 8. 17% Protein Diet
Protein (%)
15.0 13.6 15.0 17.0
14.6 13.2 14.6 16.5
TSAA (%)
.50
.50
.60
.57
.49
.49
.58
.55
Lys Tallow (%) (%)
.73
.62 • 72 .87
.70
.60
.70
.84
0.0 0.0 0.0 0.0
3.0 3.0 3.0 3.0
44
Table 13. Effects of experimental diets on performance of laying hens housed at different temperatures (Experiment 2)
Basal NRC Basal 17% Basal NRC Basal 17% NRC AA NRC + Protein NRC AA NRC + Protein
Diet Rest. .1% Met Diet Diet Rest. .1% Met Diet
------------- Without Tallow -------------- ------------- With 3% Tallow -------------Egg Production (%)
73.9de 69.5 f 82.1 a 75.9cd 71.5ef 74.Ide 73.Idef 81.8a House 10 (I9.0°C)
House 11 (21.6°C) 79.9abc 76.3bcd 80.2ab 78.3abc 79.0
abc 79.1
abc 79.6abc 76.5bcd
Egg Mass (g/d) 43.3fg 40.2h 48.1 ab 45.1 cdefg 42.6gh 43.1 fg 44.0efg 48.7a House 10 (I9.0°C)
House 11 (2I.6°C) 47.4abc 44.1 defg 46.7 abc 46.6abcd 46.7 abc 45.8bcde 47.5 abc 45.2cdef
Feed Conversion (kg/dz) 1.87ab 1.87s 1. 65 efg 1.85abc 1. 76cd 1. 78sbcd 1. 77bcd 1.61 g House 10 (I9.0°C)
House 11 (2I.6°C) 1. 72def 1.77abcd I.62g 1. 74de 1. 63 fg 1. 63 fg 1.61 g 1. 73def
Bod~ Weight (kg) 1. 85cde 1. 79 f I.84e I.88bcd 1. 85de 1.83e 1.89abc 1.91 ab House 10 (19.0°C)
House 11 (21.6°C) 1.85de 1.83e 1. 77£ 1.85cde 1.89ab 1. 78 f 1. 84de I.92a
Protein Intake (g) 16.5d 14.2h 16.7d 19.3a 15.0fg 14.3h 15.3f 17.9c House 10 (I9.0°C)
House 11 (21.6°C) 16.9d 14.8g 16.0e 18.8
b 15.3
fg 14.0h 15.1 fg 17.4c
TSAA Intake (mg) 553.6ef
521.8g
667.0a
649.8b
503.Ih
523.3g
611.5c
601. 3cd
House 10 (19.0°C)
House 11 (2I.6°C) 567.7e 544.9f 638.9
b 633.7b
512.6g 513.4gh
601. 8cd 586.3d
Lysine Intake (mg) 792.4e 643.9 i 803.0e 987.2a 720.1g 645.7 i 736.3g 913.5c House 10 (I9.0°C)
House 11 (21.6°C) S12.6e 672.4h 769.2 f 962.Sb 733.7g 633.5 i 724.6g 890.7d
a-k, X-Y . h' h . .. 'f' I d'ff ( < 05) Means W1t 1n a parameter not aV1ng common letter superscr1pts are s1gn1 1cant y 1 erent P.
Means
75.3Y
78.6X
44.4Y
46.3X
1. 77X
1.68Y
1.85
1.84
16.2
16.1
578.9
574.9
780.2
774.9
.pV1
46
TSAA level than that recommended by NRC (1984), supported an egg
production level of 82.1% which was the highest obtained in this house.
Tallow supplementation to the NRC basal diet (Diet 1) did not
significantly affect egg production rate (Table 13). At the lower
protein level (Diet 2), tallow produced a significant increase in egg
production to 74.1% in comparison with 69.5% production in the absence
of tallow. A significant improvement in egg production rate was also
obtained with the addition of tallow to the high protein diet (Diet 4)
in this house; while tallow supplementation reduced egg production for
hens fed the NRC basal diet supplemented with Met (Diet 3). Highest
egg production rates in the open house (House 10) were obtained with
the Met supplemented basal diet (Diet 3) and the 17% protein diet (Diet
4) with added tallow.
A different response pattern occurred in the insulated and
evaporatively cooled house (House 11). Significantly higher egg
production was obtained with the NRC basal diet (Diet 1) in this house
in comparison with the same diet in the open house (Table 13).
Lowering the total protein level to 13.6% from 15%, with the same amino
acid levels (Diet 2), did not significantly affect egg production in
this house. Neither increasing the TSAA level in the NRC basal diet
(Diet 3) nor increasing the total protein level to 17% (Diet 4) had any
significant effect on egg production rate. Tallow supplementation also
did not significantly affect egg production with any of the diets in
this house. Overall egg production in House 11 was significantly
better than in House 10 (78.6 vs. 75.3%).
47
Egg mass followed patterns similar to egg production in the
two houses and with the various experimental diets, indicating that the
parameters studied did not significantly affect egg weight. Hens fed
the Met supplemented basal diet (Diet 3) had a higher egg mass than
hens fed other diets without tallow at both temperatures (Table 13).
Egg mass for birds at 21.6°C (House 11) was significantly higher than
for birds housed at 19.0°C (House 10). At 19.0°C (House 10) fat
addition increased egg mass significantly from 40.2 to 43.1 g egg/d for
birds fed Diet 2 and from 45.1 to 48.7 g egg/d for birds fed the
regular diet (Diet 4); while tallow supplementation did not
significantly affect egg mass for any diet at 21.6°C (House 11).
Body weight of hens fed the low protein diet (Diet 2) and the
Met supplemented basal diet (Diet 3) at 19.0°C (House 10) were
significantly increased due to 3% fat addition (Table 13). At 21.6°C
(House 11) tallow supplementation significantly decreased body weight
of birds fed the 13.6% protein diet (Diet 2) and significanly increased
body weight with all other diets.
Significant differences in feed conversion occurred due to
temperature. Birds at 19.0°C (House 10) had a poorer feed conversion
than those at 21.6°C (House 11). It is expected that birds at low
environmental temperatures would have poorer feed conversions than
those at thermoneutral temperatures. Feed is converted to heat to
maintain body temperature rather than to net energy (NE) for
production. Low feed conversions were obtained at both temperatures
when the Met supplemented diet (Diet 3) without tallow was fed. This
is an indicator of the importance of TSAA levels on laying hen
48
performance. Fat addition to this diet did not result in improved feed
conversion. Feed converS10n was improved with tallow supplementation
to the 17% protein diet (Diet 4) at 19.0°C (House 10) and to the 13.6%
protein diet (Diet 2) at 21.6°C (House 11). Tallow supplementation of
the NRC basal diet (Diet 1) resulted in improved feed conversion in
both houses, while other diets did not show any significant improvement
with tallow at either temperature.
Protein intake was significantly higher with the 17% protein
diet (Diet 4) at both temperatures. Except the 13.6% protein diet at
19.0°C, protein intakes for all diets at both temperatures decreased
significantly due to fat addition. However, protein intakes for birds
housed at 21.6°C were not significantly higher than those at 19.0°C.
As expected, TSAA intake increased significantly with the Met
supplemented basal diet (Diet 3) at both temperatures in comparison
with the NRC basal diet (Diet 1). Fat supplementation resulted in
significant decreases in TSAA intake for all diets at both
temperatures, except for the 13.6% protein diet at 19.0°C. At the
lower environmental temperature (19.0°C) TSAA intake was not
significantly higher than at 21.6°C. Lys intake followed the same
pattern as TSAA, except high Lys intake occurred with the 17% protein
diet (Diet 4) at both temperatures (Table 13). These results indicate
that fat supplementation decreased both protein and amino acid intakes;
therefore, it is important to adjust dietary protein and amino acid
levels with both fat addition and environmental temperature.
Effects of dietary tallow supplementation on energy
utilization by laying hens are shown in Table 14. ME intakes were
Table 14. Experimental diet effects on energy utilization by laying hens housed at different temperatures (Experimen t 2)
Basal NRC Basal 17% Basal NRC Basal 17% NRC AA NRC + Protein NRC AA NRC + Protein Means
Diet Rest. .1% Met Diet Diet Rest. .1% Met Diet
------------- Without Tallow -------------- ------------- With 3% Tallow -------------Dietarr HE ekcal/g)
House 10 (19.0°C) 2.78 2.86 2.78 2.70 3.02 2.98 3.09 2.87 2.89
House 11 (21.6°C) 2.73 2.71 2.74 2.60 2.89 2.89 3.01 2.82 2.80
HE Intake ekcal/d) 306.2cd 298.6def 306.1 cd 321.1 ab ;11.3X House 10 (19.0°C) 310.4c 311. Sc 32S.Sa 310.8c
House 11 e21.6·C) 308.0c 295.1 efg 293.0fg 288.2g 303.4cde 30S.4cd 312.3bc 298.4def 300.SY
Energl Balance ekcal/d) 72.Sde 68.8e 81.0ab 77.6abcd 74.1 cde 73.0de 76.4bcd 83.3a 7S.8Y House 10 e19.0°C)
House 11 (21.6°C) 79.4abc 7S.Sbcd 7S.6abcd SO.2abc 79.9abc 77.7abcd S1.0ab 80.0abc 79.0X
Gross Energetic Eff. (%) 23.6de 23.1e 26.0ab 2S.4bcd 23.7 cde 23.4e 26.7ab 24.3Y House 10 eI9.0°C) 22.7e
House 11 e21.6°C) 2S.7b 25.5bc 26.8ab 27.7a 26.2ab 2S.3bcd 25.9b 26.7ab 26.2X
Maint. Energl (kcal/d) 203.7bc 199.Sbcde 197.8cdef 201. Sbcd 20S.3b 214.3a 199.2bcde 204 .• 2X House 10 e19.0·C) 212.2a
House 11 e21.6°C) 196.9def 191.8f 184.7g 184.4g 19S.2ef 193.gef 19S.3cde 193.7ef 192.4Y
ME Cons. > Maint. ekcal/d) f House 10 e19.0·C) 102.Se 99.1 f li2.6ab 104.6cdef 106.2bcdef 109.0abcde 111.2abcd 111.6abc 107.1
House 11 (21.6·C) 111.1 abcd 103.3ef I08.3abcde 103.7def 108.2abcde 111.6abc 114.0a 104.7cdef 10S.1
Net Energetic Eff. e%) House 10 (19.0·C) 70.S fghi 69.6hi 71.Sefg 73.2cde 69.9ghi 66.9 j 68.7 ij 74.6bc 70.7Y
House 11 e21.6·C) 71.Sefgh 72.7cdef 72.4def 76.Sa 74.2bcd 69.4hi 70.9fgh 76.2sb 73.0X
HI + Activitl (kcal/d) 90.4cd 92.8c 88.0cde 82.8def 94.8bc 107.2a 102.6ab 79.5 f 92.3X House 10 (19.0°C)
House II (21.6°C) S8.3cde 80.gef 81.2ef 67.3h 79.1 fg 93.8c 91.4c 71.3gh 81. 7Y
a-j,X-YM ' h' h ' •. 'f' d'ff ( < OS) eans W1t 1n a parameter not aV1ng common letter super9cr1pts are 91gn1 1cantly 1 erent P.
.j::-\D
50
increased significantly for both the low protein and Met supplemented
diets (Diets 2 and 3) due to fat supplementation at both temperatures.
In the case of hens fed the 13.6% protein diet (Diet 2), this
improvement in ME intake with tallow supplementation may account for
the increases in egg production through higher amounts of ME available
for production. However, the extra ME consumed by hens fed the Met
supplemented basal diet appeared primarily as gains in body weight.
Average ME intakes for birds housed at 19.0°C were significantly
higher than those at 21.6°C, suggesting that birds housed at 19.0°C
needed around 3% more energy to maintain their body temperature than
those at 21.6°c.
In the conventional cage house (House 10), energy balance was
significantly higher for birds fed the Met supplemented basal diet
(Diet 3) than for those fed the NRC basal diet (Diet 1), indicating a
higher requirement for TSAA under these conditions. Energy balance was
not significantly affected by tallow supplementation in either house
nor by both diet in the insulated and evaporatively cooled house (House
11) (Table 14). Average energy balance was significantly higher at
21.6°C (House 11) than at 19.0°C (House 10).
Gross energetic efficiency dropped significantly from 26 to
23.4% when fat was added to the Met supplemented basal diet (Diet 3) at
19.0°C (House 10) and no significant differences occurred with the
other diets at either temperature. Hens housed at 21.6°C (House 11)
had higher gross energetic efficiencies than those at 19.0°C (House
10). Net energetic efficiency followed the same trend as gross
energetic efficiency.
51
The average maintenance energy requirement of birds housed at
19.0°C (House 10) was 204.2 kcal/d, while those at 21.6°C (House 11)
had a maintenance requirement of. 192.4 kcal/d, about 5.8% less. ME
consumption above maintenance did not differ significantly due to
housing temperature.
No change in starch retention was observed due to diet, fat
addition, or to housing. Protein retention decreased slightly from
27.7 to 25% as fat was added to the diets. On the other hand, fat
retention increased significantly from 58.9 to 73.9% with tallow
supplementation.
Summary
An experiment was conducted to evaluate the effects of
dietary formulation and tallow supplementation on laying hen
performance in two types of housing. Although there are economic
benefits which may be realized from feeding low dietary protein levels,
the results of this study show that reducing the total protein level
below that recommended by the NRC (1984) produced a significant
reduction in egg production in birds housed in a conventional open cage
house (House 10). Met supplementation to provide a total of .60% TSAA
was required for maximum egg production for hens housed in the open
house. A significant increase in egg production was obtained with the
low protein diet (Diet 2) when 3% tallow was added, suggesting that
lower protein levels may be used for laying hens under some conditions
if fat is incorporated in the diet. However, the level of egg
production supported by this combination was significantly below that
obtained with the 17% protein diet (Diet 4), either with or without
added tallow. The limiting nutrient in all of the diets, other than
the 17% protein formulation, appeared to be Lys. The highest egg
production rates were associated with the highest intakes of Lys and
the response appeared to be limited by TSAA intakes iu some of the
diets.
52
For birds housed in the insulated and evaporatively cooled
house (House 11) the diet based on the NRC amino acid requirements
(Diet 2) appeared to be optimal for performance even with a lower
protein level. No additional benefits were obtained in egg production
with the feeding of 3% tallow in any of the diets under these housing
conditions. The main effects of added tallow were improved feed
conversions which, of course, reduce feed costs of producins eggs.
The results of this study indicate that formulation of laying
hen diets based on amino acid requirements without consideration of
total protein level may be used to reduce feed costs of egg production
provided care is taken to maintain adequate intake levels of amino
acids with variation in environmental temperature. The impFovement in
production with added tallow in the conventional house suggests the
need for further research to determine an explanation. TSAA and lysine
intake did not increase as the environmental temperature increased.
REFERENCES
Ackman, R. G., 1969. Gas-liquid chromatography of fatty acids and esters. Pages 329-381 in Methods in Enzymology v. XIV. J. M. Lowenstein, ed. Academic Press, New York, NY.
Adams, R. L., F. N. Andrews, E. E. Gardiner, W. E. Fontaine, and C. W. Carrick, 1962a. The effects of environmental temperature on the growth and nutritional requirements of the chick. Poultry Sci. 41:588-594.
Adams, R. L., F. N. Andrews. J. C. RogIer, and C. W. Carrick, 1962b. The sulfur amino acid requirement of the chick from 4 to 8 weeks of age as affected by temperature. Poultry Sci. 41:1801-1806. .
Aitken, J. R., G. E. Dickerson, and R. S. Gowe, 1973. Effect of intake and source of protein on laying performance of seven strains under single and double cage housing. Poultry Sci. 52:2127-2134.
Al-Hozab, A. A., 1985. The effect of tallow on true metabolizable energy of some poultry feedstuffs. M.S. Thesis, Univ. of Arizona, Tucson, AZ.
Association of Official Analytical Chemists, 1980. Official Methods of Analysis. 13th ed. W. Horwitz, ed. Association of Official Analytical Chemists, Washington, DC.
American Oil Chemist's Society, 1972. Official and Tentative Methods. 3rd ed. Vol. 2. W. E. Link, ed. American Oil Chemist's Society, Champaign, IL. Method Ce 2-66.
Bacon, W. L., A. H. Cantor, and M. A. Coleman, 1981. Effect of dietary energy environmental, &nd sex of market broilers on lipoprotein composition. Poultry Sci. 60:1282-1286.
Baldini, J. T., and H. R. Rosenberg, 1955. The effect of productive energy level of the diet on the methionine requirement of the chick. Poultry Sci. 34:1301-1307.
Barott, H. G., and E. M. Pringle, 1946. Energy and gaseous metabolism of the chicken from hatch to maturity as affected by temperature. J. Nutr. 31:35-50.
53
Biely, J" and B. March, 1954. Fat studies in poultry. 2. Fat supplements in chick and poult rations. Poultry Sci. 33:1220-1227.
Blakely, R. M., H. I. MacGregor, and D. Hanel, 1965. Performance of turkeys on finishing diets containing different fats. Can. J. Anim. Sci. 45:59-61.
54
Brown, W.O., J. J. Waring, and E. Squance, 1965. A study of the effect of variation in the calorie-protein ratio of a medium energy diet and a high energy diet containing sucrose on the efficiency of egg production in caged layers. Br. Poult. Sci. 6:59-66.
Burlacu, G., 1969. The specific dynamic action of amino acids in hens. Pages 149-157 in Energy Metabolism of Farm Animals. K. L. Blaxter, J. Kielanowski, and G. Thorbeck, eds. Oriel Press, Newcastle-upon-Tyne.
Carew, L. B., Jr., and F. W. Hill, 1964. Effects of corp oil on metabolic efficiency of energy utilization by chicks. J. Nutr. 83:293-299.
Clegg, K. M., 1965. The application.of the anthrone reagent to the estimation of starch in cereals. J. Sci. Food Agr. 7:40-44.
Daghir, N. J., 1973. Energy requirements of laying hens in a semi-arid continental climate. Br. Poult. Sci. 14:451-461.
Dale, N. M., and H. L. Fuller, 1979. Effects of diet composition on feed intake and growth of chicks under heat stress. 1. Dietary fat levels. Poultry Sci. 58:1529-1534.
Dale, N. M., and H. L. Fuller, 1980. Effects of diet composition on feed intake and growth of chicks under heat stress. 2. Constant vs. cycling temperatures. Poultry Sci. 59:1434-1441.
Dale, N. M., and H. L. Fuller, 1981. The use of true metabolizable energy (TME) in formulating poultry rations. Pages 50-57 in Proc. Georgia Nutr. Conf., Univ. of Georgia, Athens, GA.
Dam, R., R. M. Leach, T. S. Nelson, L. C. Norris, and F. W. Hill, 1959. Studies on the effect of quantity and type of fat on chick growth. J. Nutr. 68:615-632.
Davidson, J., I. MacDonald, J. Mathieson, and R. B. Williams, 1961. Utilization of dietary energy by poultry. 2. Effects of indigestible organic matter and protein on the utilization of metabolizable energy for growth. J. Sci. Food Agr. 12:425-439.
Davis, R. H., O. E. M. Hassan, and A. H. Sykes, 1972. The adaptation of energy utilization in the laying hen to warm and cool ambient temperature. J. Agr. Sci., Camb. 79:363-369.
Davis, R. H., O. E. M. Hassan, and A. H. Sykes, 1973. Energy utilization in the laying hen in relation to ambient temperature. J. Agr. Sci., Camb. 81:173-177.
55
Dillon, J. F., 1974. Energy intake regulation by layers according to diet, productivity and environment. Aust. J. Exp. Agr. Anim. Husb. 14:133-140.
Donaldson, W. E., G. E. Combs, G. L. Romoser, and W. C. Supplee, 1955. Body composition, energy intake, feed efficiency, growth rate, and feather condition of growing chickens as influenced by calorie-protein ratio of ration. Poultry Sci. 34:1190 (Abstr. ).
Donaldson, W. E., G. E. Combs, and G. L. Romoser, 1956. Studies on the energy levels in poultry rations. 1. The effect of calorie:protein ratio of the ration on growth, nutrient utilization and body composition of chicks. Poultry Sci. 35: 1100-1105.
Emmans, G. C., 1974. The effect of temperature on the performance of laying hens. Pages 79-90 in Energy Requirements of Poultry. T. R. Morris and-a. M. Freeman, eds. Br. Poult. Sci. Ltd., Edinburgh.
Fernandez, R., A. J. Salman, and J. McGinnis, 1973. Effect of feeding different protein levels and of changing protein level on egg production. Poultry Sci. 52:64-69.
Forbes, E. B., and R. W. Swift, 1944. Associative dynamic effects of protein, carbohydrate and fat. J. Nutr. 27:453-468.
Fuller, H. L., and M. Rendon, 1979. Energetic efficiency of corn oil and poultry fat at different levels in broiler diets. Poultry Sci. 58:1234-1238.
Gerry, R. W., 1963. The supplementary value of greases, tallows and oils in rations for chickens. Maine Agr. Exp. Sta. Bull. 611, Univ. of Maine.
Gleaves E. W., and A. A. Salim, 1982. The effect of lactose supplement and source of feed intake and production characteristics of laying hens. Poultry Sci. 61:2390-2397.
Gomez, M. X., and D. Polin, 1974. Influence of cholic acid on the utilization of fats in the growing chicken. Poultry Sci. 53:773-781.
56
Guillaume, J., and J. D. Summers, 1970. Maintenance energy requirement of the rooster and influence of plane of nutrition on metabolizable energy. Can. J. Anim. Sci. 50:363-369.
Hill, F. W., and L. M. Dansky, 1950. Studies on the protein requirements of chicks and its relation to dietary energy level. Poultry Sci. 29:763 CAbstr.).
Hill, A. T., and J. R. Hunt, 1980. Pullet and layer flock management. Pages 54-63 in A Review of Research into Egg Production and Marketin~ Publ. 5126. J. Lancaster, ed. Agriculture Canada, Ottawa, ONT.
Hochreich, H. J., C. R. Douglas, I. H. Kidd, and R. H. Harms, 1958. The effect of dietary protein and energy level upon production of Single Comb White Leghorn hens. Poultry Sci. 37: 949-953.
Horani, F., and J. L. Sell, 1977a. The modifying effect of calorie:protein ration on laying hen performance and on the "extra metabolic effect" of added fat. Poultry Sci. 56:1981-1988.
Horani, F., and J. L. Sell, 1977b. Effect of feed grade animal fat on laying hen performance and on metabolizable energy of rations. Poultry Sci. 56:1972-1980.
Hurwitz, S., and S. Bornstein, 1973. The protein and amino acid requirements of laying hens: suggested models for calculation. Poultry Sci. 52:1124-1134.
Hurwitz, S., D. Sklan, and I. Bartov, 1978. New formula approaches to the determination of energy and amino acid requirements of chicks. Poultry Sci. 57:197-205.
Iman, R. L., and W. J. Conover, 1983. A Modern Approach to Statistics. John Wiley and Sons, Inc., New York, NY.
Jackson, N., H. R. Kirkpatrick, and R. B. Fulton, 1969. An experimental study of the utilization, by the laying hen, of dietary energy partially supplied as animal fat. Br. Poult. Sci. 10:115-126.
Jensen, L. S., G. W. Schumaier, and J. D. Latshaw, 1970. "Extra caloric" effect of dietary fat for developing turkeys as influenced by calorie-protein ratio. Poultry Sci. 49:1697-1704.
John, M. J., 1976. Alternative approaches to adoption of animal technology. Pages 581-592 in Proc. World Food Conf., Iowa State University Press, Ames, IA.
Jones, B. N., S. Paabo, and S. Stein, 1981. Amino acid analysis and enzymatic sequence determination of peptides by an improved o-phthaldialdehyde precolumn labeling procedure. J. Liq. Chromatogr. 4(4):565-586.
Kalmbach, M. P., and L. M. Potter, 1959. Studies in the evaluating energy content of feeds for the chick. 3. The comparative values of corn oil and tallow. Poultry Sci. 38:1217.
57
Kleiber, M., 1945. Dietary deficiencies and energy metabolism. Nutr. Abstr. Rev. 15:207-222.
Kleiber, M., and J. E. Dougherty, 1934. temperature on the utilization J. Gen. Physiol. 17:701-726.
The influence of environmental of food energy in baby chicks.
Lal1, S. P., and S. J. Slinger, 1973. The metabolizable energy content of rapeseed oil foots and the effect of blending with other fats. Poultry Sci. 52:143-151.
Leeson, S. J., and J. D. Summers, 1976. Fat ME values: The effect of fatty acid saturation. Feedstuffs 48(46):26-27.
Leveille, G. A., R. Shapiro, and H. Fisher, 1960. Amino acid requirements for maintenance in the adult rooster. IV. The requirements for methionine, cystine, phenylalanine, tyrosine and tryptophan; the adequacy of the determined requirements. J. Nu tr. 72: 8-5.
Lewis, D., and C. G. Payne, 1966. Fats and amino acids in broiler rations. 6. Synergistic relationship in fatty acid utilization. Br. Poult. Sci. 7:209-218.
Lillie, R. J., J. R. Si~emore, J. L. Milligan, and H. R. Bird, 1952. Thyrotropein and fats in laying diets. Poultry Sci. 31:1037-1042.
March, B. E., and J. Biely, 1963. The effects of dietary fat and energy levels on the performance of caged laying birds. Poultry Sci. 42:20-24.
March, B. E., and J. Biely, 1972. The effect of energy supplied from environment heat on the response of chicks to different levels of dietary lysine. Poultry Sci. 51:665-668.
Mateos, G. G., and J. E. Sell, 1980a. Influence of graded levels of fat on utilization of pure carbohydrate by the laying hen. J. Nutr. 110:1894-1903.
Mateos, G. G., and J. L. Sell, 1980b. Influence of carbohydrate and supplemental fat source on the metabolizable energy of the diet. Poultry Sci. 59:2129-2135.
Mateos, G. G., and J. L. Sell, 1981. Nature of the extrametabolic effect of supplemental fat used in semipurified diets for laying hens. Poultry Sci. 60:1925-1930.
58
Mateos, G. G., J. L. Sell, and J. A. Eastwood, 1982. Rate of food passage (transit time) as influenced by level of supplemental fat. Poultry Sci. 61:94-100.
Matterson, L. D., 1. M •. Potter, L. D. Stinson, and E. P. Singsen, 1955. Studies on the effect of varying protein and energy level in poultry rations on growth and feed efficiency. Poultry Sci. 34:1210 (Abstr.).
McNaughton, J. L., J. D. May, F. N. Reece, and J. W. Deaton, 1978. Lysine requirement of broilers as influenced by environmental temperatures. Poultry Sci. 57:75-64.
Mickelberry, W. C., J. C. RogIer, and W. J. Stadelman, 1966. The influence of dietary fat and environmental temperature upon chick growth and carcass composition. Poultry Sci. 45:313-321.
Mitchell, H. H., and W. T. Haines, 1927. The critical temperature of the chicken. J. Agr. Res. 34:549-557.
Mongin, P., and B. Sauveur, 1974. Voluntary food and calcium intake by the laying hen. Br. Poult. Sci. 15:349-359.
National Research Council, 1981. Animals and Glossary of Press, Washington, DC.
Nutritional Energetics of Domestic Energy Terms. National Academy
National Research Council, 1984. Nutrient requirements of poultry. 8th rev. ed. National Academy Press, Washington, DC.
Nivas, S. C., and M. L. Sunde, 1969. per day and phase feeding.
Protein requirements of layers Poultry Sci. 48:1672-1678.
Osbaldiston, G. W., and D. W. B. Sainsbury, 1963. Control of environment in poultry house. 2. Broiler house experiments. Vet. Rec. 75:193-202.
Pesti, G. M., 1982. Characterization of the response of male broiler chickens to diets of various protein and energy contents. Br. Poult. Sci. 23:527-537.
Peterson, D. W., C. R. Grau, and N. F. Peek, 1945. Growth and food consumption in relation to dietary levels of protein and fibrous bulk. J. Nutr. 52:241-257.
Powell, T. S., C. R. Douglas, R. H. Stonerock, and R. H. Harms, 1974. Feed intake of hens fed various levels of energy from feed and/or sucrose-water. Nutr. Rep. Int. 9:9-13.
Reece, F. N., and J. L. McNaughton, 1982. Effect of dietary nutrient density on broiler performance at low and environmental temperature. Poultry Sci. 61:2208-2211.
Reid, B. L., 1976. Estimated daily protein requirements of laying hens. Poultry Sci. 55:1641-1645.
Reid, B. L., 1981. Fat levels in layer feeds. J. Am. Oil Chem. Soc. 58(3):306-309.
Reid, B. L., 1984. Tallow and laying hen nutrition. (Unpublished data). Univ. of Arizona, Tucson, AZ.
59
Reid, B. L., and P. M. Maiorino, 1984. Dietary sulfur amino acid level and energy utilization in laying hens. Poultry Sci. 63:2048-2413.
Reid. B. L., and C. W. Weber, 1973. Dietary protein and sulfur amino acid levels for laying hens during heat stress. Poultry Sci. 52:1335-1343.
Reid, B. L., and C. W. Weber, 1974. Lack of sulfur amino acid sparing effect with ammonium sulfate and sodium sulfate in laying hen diets. Poultry Sci. 53:964-969.
Reid, B. L., and C. W. Weber, 1975. Supplemental dietary fat and laying hen performance. Poultry Sci. 54:422-428.
Scott, H. M., L. D. Matterson, and E. P. Singsen, 1947. Nutritional factors influencing growth and efficiency of feed utilization. 1. The effect of the source of carbohydrate. Poultry Sci. 26:554 (Abstr.).
Scott, M. L., M. C. Nesheim, and R. J. Young, 1982. Nutrition of the Chicken. M. L. Scott and Associates, Publishers, Ithaca, NY.
Sell, J. L., and G. G. Mateos, 1981. Influence of supplemental fat on utilization of dietary energy and rate of food passage in poultry. Pages 161-176 in Proc. Georgia Nutr. Conf.
Sell, J. L., and W. J. Owings, 1980. Dietary fat supplementation and ME:nutrient ratio for growing turkeys. Pages 100-114 in Proc. 40th Minn. Nutr. Conf.
Sell, J. L., L. G. Tenesaca, and G. L. Bales, 1979. Influence of dietary fat on energy utilization by laying hens. Poultry Sci. 58:900-905.
60
Shannon, D. W. F., and W. O. Brown, 1969. Loss of energy and nitrogen on drying poultry excreta. Poultry Sci. 48:41-43.
Sibbald, I. R., 1978. The true metabolizable energy values of mixture of tallow with either soybean oil or lard. Poultry Sci. 57:474-477.
Sibbald, I. R., and J. K. G. Kramer, 1977. The true metabolizable energy values of fats and fat mixtures. Poultry Sci. 56:2079-2086.
Sibbald, I. R., and J. K. G. Kramer, 1978. The effect of the basal diet on the true metabolizable energy value of fat. Poultry Sci. 57:685-691.
Sibbald, I. R., and K. Price, 1977. The effects of level of dietary inclusion and of calcium on the true metabolizable energy values of fats. Poultry Sci. 56:2070-2078.
Sibbald, I. R., S. J. Slinger, and G. C. Ashton, 1961. Factors affecting the metabolizable energy of poultry feeds. 2. Variability in the M.E. values attributed to samples of tallow and undegummed soybean oil. Poultry Sci. 40:303-308.
Solberg, J., 1971. Effects of moderate lysine deficiency on digestibility and metabolizable energy of diets and on nitrogen retention and uric acid excretion in chicks. Acta. Agr. Scand. 21:192-198.
Sunde, M. L., 1956. A relationship between protein level and energy level in chick rations. Poultry Sci. 35:350-354.
Thayer, R. H., G. E. Hubbell, J. A. Aksboham, R. D. Morrison, and E. C. Nelson, 1974. Daily protein intake requirement of laying hens. Poultry Sci. 53:354-364.
Touchburn, S. P., and E. C. Naber, 1966. The energy value of fats for growing turkeys. Pages 109-195 in Proc. XlIIth World's Poult. Cong., Kiev.
Valencia, M. E., P. M. Maiorino, and B. L. Reid, 1980. Energy utilization in laying hens. 3. Effect of dietary protein level at 21 and 32 C. Poultry Sci. 59:2508-2513.
61
Vohra, P., W. o. Wilson, and T. D. Siopes, 1979. Egg production, feed consumption, and maintenance energy requirements of Leghorn hens as influenced by dietary energy at temperatures of 15.6 and 26.8 C. Poultry Sci. 58:674-680.
Waibel, P. E., 1958. Effectiveness of unknown growth factors, antibiotic, and animal fat in turkey poult rations. Poultry Sci. 37:1144-1149.
Waring, J. J., and W. O. Brown, 1965. A respiration chamber for the study of energy utilization for maintenance and production in laying hen. J. Agr. Sci., Camb. 65:139-146.
Waring, J. J., and W. O. Brown, 1967. Calorimetric studies on the utilization of dietary energy by the laying White leghorn hen in relation to plane of nutrition and environmental temperature. J. Agr. Sci., Camb. 68:149-155.
Waring, J. J., and D. W. F. Shannon, 1969. Studies on the energy and protein values of soya bean meal and two varieties of field beans using colostomized laying hens. Br. Poult. Sci. 10:331-336.
Warkentin, J., L. Warkentin, and A. C. Ivy, 1943. The effect of experimental thyroid abnormalities on appetite. Am. J. Physiol. 139:139-146.
Wilder, o. M., M. P. Cullen, and o. G. Rasmussen, 1959. Metabolizable energy values of different types and grades of fats used in practical chick diets. Poultry Sci. 38:1259-1260.
Wiseman, J., and D. J. A. Cole, 1983. Determination of the metabolizable energy content of a commercial fat blend fed to broiler chicks. World's Poult. Sci. J. 39(3):242 (Abstr.)
Yacowitz, H., 1953. Supplementation of corn, soybean oil meal rations with penicillin and various fats. Poultry Sci. 32:930 (Abstr. ).
Young, R. J., 1961. The energy value of fats and fatty acids for chicks. 1. Metabolizable energy. Poultry Sci. 40:1225-1233.
Young, R. J., and R. L. Garrett, 1963. Effect of oleic and linoleic acid on the absorption of saturated fatty acids in the chick. J. Nutr. 81:321-329.
Young, R. J., R. L. Garrett, and M. Griffith, 1963. Factors affecting the absorbability of fatty acid mixtures high in saturated fatty acids. Poultry Sci. 42:1146-1154.