lecture no.9+10--an 202-final

7/26/2019 Lecture No.9+10--AN 202-final

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Minerals

In general, forages are good sources of calcium,while grains and animal products are fair to goodsources of phosphorus.

When planning a mineral supplementation programfor forage-fed cattle, it is important to realize thatbioavailability of minerals from forage may be low.

As a rule of thumb, mineral values in forages shouldbe discounted by 50 percent to account forpotentially low bioavailability.

Mineral content in forage often mirrors theconcentration of minerals in the soil.

Pasture fertilization schemes and stage of maturity ofthe forage affect mineral content and mineralbioavailability.

Calcium

During lactation-low plasma calcium--- theproduction of parathyroid hormone (PTH)increases

increase absorption from the astrointestinal tract

increase mobilization from bone. when supply exceeds demand

the antagonist of PTH, calcitonin, reducesabsorption and increases calcium accretion intobone.


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Minerals

Calcium (cont)

At the beginning of lactation --thedepletion of calcium status occurssuddenly, over about a 10-h period.

Colostrum contains about 2 g Ca l1

large outflow of calcium in milk, togetherwith a depressed appetite aroundparturition-- paralysis (parturient paresis


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Calcium (cont)

If calcium intake can be limited to 50 g day1 orless during the latter part of the non-lactatingperiod, PTH production increases and themobilization of the substantial bone reservesstarts before the onset of lactation.

During lactation, calcium intake should be about3 g kg1 milk.

Sources: bonemeal, lime, meat meal, fish meal,milk, legumes, pulses, dicalcium-phosphate


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magnesium

a mineral that can easily be deficient in lactating cowsgrazing intensively managed pastures.

Some magnesium can be mobilized from bone tissueduring a deficiency. The acute form of the disorder grass tetany A chronic form of hypomagnesaemia also exists, with a

gradual loss of condition and a stiff gait. Nitrogen fertilizer -- risk factor for deficiency Magnesium requirements can be estimated factorially as

18 mg Mg kg1 live weight per day for maintenance(endogenous losses) + 2.7 g kg1 live weight gain +0.74 g Mg l 1 of milk +3g Mg day1 for the last 8 weeksof pregnancy.


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phosphorus

In many feeds most of the phosphorus is in theform of phytate,

readily available to ruminants (rumenmicroorganisms)

not to monogastric animals,

Problems are most likely, to occur in cattle onrange-lands -- declines as the plant matures.,

When the soil phosphorus status is low and theforage is mature (Ternouth, 1990).

Phosphorus (cont.) The absorption is mainly in the small intestine and is actively controlled by

vitamin D. Absorption declines markedly with age, from nearly 100% in the suckled calf

to 43% for cattle over 1 year of age. very high calcium:phosphorus ratio (>10:1) in the feed reduces phosphorus

availability.Deficiency

stiff gait bone abnormalities

reduced production (growth rate or milk production), picaRequirements

difficult to estimate because absorption varies widely. If it is assumed to be60%, most rationing systems suggest that a dairy cow will require about

24 g day1 for maintenance and 1.5 g l1 for milk production, or a phosphorus content in the ration of about 0.5% for a high-yielding cow. Growing cattle are likely to require a phosphorus concentration in the ration

of about one-half of this value.


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phosphorus

grazing conditions--the phosphorus contents ofherbage can be increased by phosphorusfertilizer quite effectively.

provided as field blocks Some phosphorus supplements, such as

dicalcium phosphate or superphosphate, arewell absorbed,

Rock phosphate is not well absorbed, isunpalatable and may contain a high fluoridecontent.


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sodium and chlorine

Even though many feeds contain enough

sodium and chlorine, supplemental cobaltiodized (blue) salt or trace mineral saltshould be available at all times.

Sulphur

Most feeds contain adequate amounts ofS for cattle.

Supplemental S may be necessary whennon-protein nitrogen sources are beingutilised in high grain feedlot diets.

The critical level in feeds is approximately1g S kg1 DM.


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Iron

Virtually all feeds contain enough Iron for cattle

The iron content of leaves is much greater than seeds or milk iron deficiency does not occur in cattle fed forage-based diets. should not be added to the diet of adult cattle at risk of

hypocupraemia,--inhibit the absorption of copperMilk has a particularly low concen-tration of iron, in relation to other

minerals-- the suckling period -- store of iron at birth in the liver(about 450 mg).

The restriction limits bacteria their growth in the mammary gland --prevent mastitis.

effectively recycled within the -- little urinary excretion. Calves that suckle their dams at pasture invariably start consuming

a few leaves of grass before the anaemia --not at risk..

Zinc

Requirements are difficult to state precisely---extensive interactions with other elements, inparticular copper, calcium and cadmium.

3040 mg Zn kg1 of feed DM is generally

recommended for most classes of cattle, unlessthe feed contains a high copper level--requirements will be greater.If a supplement is required-- trace mineralizedsalt or mineral supplement.


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copper

several minerals will inhibit the absorption-

-competitive inhibition--- molybdenum,sulphur, iron, zinc, cadmium and possiblycalcium.

The complexity of the interrelationshipsbetween these elements makes theprediction of copper availability difficult.

Copper deficiencies can cause a reduced

growth rate in cattle in susceptible areas.

Iodine (I) and Cobalt

Iodine (I) --- trace amounts by the thyroid gland,which influences the rate of metabolism in thebody.

goitre. Cobalt--Deficiencies are common where soils

have low cobalt concentrations If soils are alkaline the uptake by the plant is low

and direct Supplementation--a salt containing both of these

elements


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Selenium

Selenium (Se) is deficient in some regions and surplusin others. "Alkali disease" or "blind staggers" occurs

when cattle eat feed containing toxic or excess amountsof Se (10 ppm) over a long period of time. "white muscle disease" in calves, lambs lower fertility and an increased incidence of retained

placentas it is beneficial to increase selenium intake for early

lactation cows up to 4 mg day1 dietary concentration recommended to avoid muscular

dystrophy (0.1 mg kg1 DM) Se can be added to salt or mineral mixes, or injected.

vitamin A Animals on green grass can store vitamin A in the liver and draw on it for 2-

3 months. Although forages may contain sufficient carotene to meet all requirements, it

is good insurance to feed vitamin A, since the carotene content of a foragedeclines in storage.

carotene concentrations are usually much less for conserved feeds typically

straw contains 5 mg -carotene kg1 of feed DM, hay 1020 mg -carotene

kg1 of feed DM, grass silage 120 mg -carotene kg1 of feed DM andmaize silage 11 mg -carotene kg1 of feed DM. Supplementation of dairy cows with 200300 mg day1 -carotene is recommended if plasma -

carotene concentrations are below approximately 2500 gl1.


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vitamin D

Compounded concentrate feeds usually contain 10002000 IUkg1 of vitamin D, which is sufficient for most purposes.

Animals kept outdoors or fed sun-cured hay do not usually suffer adeficiency, whereas animals kept indoors and fed silage may do so.

Inadequate vitamin D intake causes osteoporosis and reducedfertility.

Large doses of vitamin D fed to dairy cows around calving mobilizecalcium from bone tissue and increase calcium uptake from the gut.

reduce the incidence of milk fever--the recommended intake for this purpose being 40,00070,000 IU day1.

vitamin C and K

poultry and ruminants can synthesize vitamin C, but there is afavorable response to supplemental C when these animals areunder stress.

Rumen bacteria make vitamin K in quantities to meet the needs ofcattle under most conditions. One exception is death loss frominternal hemorrhage or surgery that may occur when cattle are fed

moldy sweet clover hay or silage. Other moldy legumes can possiblycause a similar problem.


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B-vitamin complex

B-vitamin complex are thiamin, biotin, riboflavin,niacin, pantothenic acid, pyridoxine, folic acid,

vitamin B12 and chol ine. Once the rumen becomes functional, bacterial

synthesis is considered to supply the normalrequirement of cattle for B-vitamins.

Milk is a source of B-vitamins for the calf. The lack of a trace mineral, cobalt, can result in a

vitamin B12 deficiency in cattle. This is becausecobalt is a part of the vitamin B12 compound and isessential for rumen bacteria to manufacture this

vitamin.

vitamin E

Problem conditions The need for vitamin E in cattle rations in has not been clearly

demonstrated. however, the following conditions might besuspected as causing a deficiency:

High-grain rations with limited or no roughage, especially high-moisture harvested grains

Feeding grains or roughages that are low in selenium

Lengthy storage of feeds High drying temperatures for feeds

Use about 50 IU per animal daily i f vitamin E supplementationof feedlot rations is deemed advisable.


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vitamin E

Problem conditions The need for vitamin E in cattle rations in has not been clearly

demonstrated. however, the following conditions might be

suspected as causing a deficiency: High-grain rations with limited or no roughage, especially high-

moisture harvested grains

Feeding grains or roughages that are low in selenium High fat levels in ration Lengthy storage of feeds High drying temperatures for feeds Feeds that have a small portion of their vi tamin E assay value

from alpha-tocopherol. Use about 50 IU per animal daily i fvitamin E supplementation of feedlot rations is deemedadvisable.

300 kg Cow 5 kg milk production (mid lactation) Milk Fat 5% Previous production (mid lactation) 10 kgpotential Step 1. Determining Nutrient RequirementMid lactation Energy= 5.55M+8.3L=13.85 Mcal Protein=284M+1010=1294g=1.294kg Calcium =7M+36.9 L=43.9 g

Phosphorus= 7M+22.8 L= 29.8 g


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Step 2. Determining Forage Intake.

Total DM intake---2.5-3% of LBW DMI may be 18 % less in early lactation In high producers DMI may be more than 4 % in mid and late

lactation Dairy cows should be fed all the forage they will consume. However, there are limits as to how much forage dairy cows can eat. Normally, the maximum consumption of high quality forage dry

matter will be about 2 1/2 percent of body weight when no grain isfed.

Somewhat less consumption can be expected from lower qualityforages.

An average herd will consume about 1.8 percent of body weight asforage dry matter when enough grain is fed to meet requirements.

Step 3. Calculate Nutrients fromForagesCP% NEl/k

g

DM % DM

Need

ed

Feed

requi

red

(As-

fed)

NEl

provi

ded

CP

provid

ed

Maize 12 1.87 89 2 2 3.74 .24Barley 10 1.76 91 2 2.25 3.52 .20

Sub-total 7.26 0.44

Req 6.93 0.694

Def 0.00 .254


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Step 4. Calculate Nutrients required fromconcnetates

Step 5. Calculate Concentrate Needed

(DM basis) 7.98/1.8=4.43

Step 6. Determine Protein contents of feed

Step 7. calculate replacement, if needed

Step 8. calculate and adjust phosphorus

contents in fed

Estimated nutrient Requirement ofanimals TDN (kg) CP (g) Ca (g) P (g)Maintenance

(400 kg B.Wt) 3.13 318 9 9 50 kg B.WT 0.28 21 1 1Maintenance+Pregnancy

400 kg B.Wt) 4.15 890 26 16 50 kg B.WT 0.37 82 3.5 2Lactation

Per kg milk prod4% fat 0.322 90 0.5 % fat 0.021 6Add 3 g calcium/kg mlik production


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Thumb rule to meet the nutrientrequirement of animals

Formulate a concentrate mixture

containing 68-72 % TDN and 20 % CP Cereals---25-35 % Oil cakes---25-35 % Cereals by-products---15-25 % Protein Conc.5-20 % Salt---1 %

Limestone 1 %

Thumb rule to meet the nutrientrequirement of animals wheat straw Conc.Maintenance

(400 kg B.Wt) 4 kg 1 kg 50 Kg B.Wt 0.25 0.25Pregnancy + 0 kgCrossbred/buffalo 1.75 kgZebu cattle 1.25 kg

Lactation

Crossbred/buffalo(2.0 kg milk) 1 kgZebu cattle(2.0 kg milk) 1 kg


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As-fedDM basis conversion

Nutrient composition of feed

As fed= % nutrient (DM basis) x % DM

100

Concentrate

Add 1 % salt, 1% mineral mix., 1 % limestone As DM values were used for TDN and CP calculation

and most of the concentrates contains about 90 % DMso

Estimated TDN (as fed)= (77.05/100)*90=69 % Estimated CP (as-fed)= (21.99/100)*90=19.8 %

21.9977.0597.00Total

2.0415.3017.0012.0090.00Rice polishing

10.0018.0020.0050.0090.00Corn gluten feed 50%

5.7515.7525.0023.0063.00Cotton Seed cake

4.2028.0035.0012.0080.00Maize

Total CP (kg)TDN (kg)QuantityCP% (DM

basis

TDN (DM

basis)


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Feeding a dairy cow (250 kg B.WT)----maintenance requirement

1.00

4.00

Quantity

As fed basisDM basis

0.262.02Recom-mended

0.292.26Total

0.200.6219.8069.002277Concnetrate

0.091.572.2538.72.543Wheat straw

Total CP

(kg)

TDN (kg))CP%DM %CP%TDN %

Assignment

Calculate the nutrient requirement (TDN, NE,CP)

Feed by thumb rule

Compare the nutrient required and nutrient

supplied1) Cow (300 kg B.Wt)

Pregnancy---last month

2) Cow (450 kg B.Wt)

Milk prod. 10 kg

lecture no.9+10--an 202-final

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