Replacement Heifers: Replacement Heifers: Target Weights, Target Target Weights, Target
Dates, and Fat Dates, and Fat SupplementationSupplementation
Rick Funston and Rick Funston and
Gene DeutscherGene Deutscher
University of NebraskaUniversity of Nebraska
Rick Funston and Rick Funston and
Gene DeutscherGene Deutscher
University of NebraskaUniversity of Nebraska
Feeding to a “Target Feeding to a “Target Weight”Weight”
% of Mature Wt @ breeding
Item 55% 65%
Pre-breeding wt 600683
Conception (21d) 30 62
Calving wt. 834 897
Calf birth wt. 71 73
Calving difficulty,% 52 29
Calf death loss,% 6 5
Fall Preg Rate, % 85 93
Effect of Time of Gain From Effect of Time of Gain From Weaning to Breeding on Weaning to Breeding on
Heifer PerformanceHeifer Performance
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Weaning Mid-Point Breeding
Per
cen
t o
f T
arg
et G
ain
No difference in ageat puberty, conceptionrate, or calf performancethe next year.Clanton et al., 1983
EVENGAIN vs LATEGAIN,Age and Weight at Puberty, no effect, 12% less feed w/LATEGAIN. Smith et al., 1995
What is the appropriate What is the appropriate Target Weight??Target Weight??
MethodsMethods
3-year study3-year study MARC II heifers – 80 each yearMARC II heifers – 80 each year Developed to either 55 or 60% of Developed to either 55 or 60% of
mature weightmature weight Placed with bulls May 20 – 45 dPlaced with bulls May 20 – 45 d Data collected through 4Data collected through 4thth
pregnancy diagnosispregnancy diagnosis
Developing heifers to Developing heifers to lower target weightslower target weights
53%53% 57%57%
Beginning WtBeginning Wt 469469 469469
Winter ADGWinter ADG 1.11.1 1.41.4
Prebreeding WtPrebreeding Wt 638638 689689
Prebreeding BCSPrebreeding BCS 5.65.6 6.06.0
Cycling %Cycling % 7474 8585
Pregnant 45 daysPregnant 45 days 9292 8888
Precalving WtPrecalving Wt 915915 940940
Precalving BCSPrecalving BCS 5.25.2 5.35.3
Calf birth WtCalf birth Wt 7373 7373
Developing heifers to Developing heifers to lower target weightslower target weights
53%53% 57%57%
Calving difficultyCalving difficulty 2121 1919
Actual WWActual WW 405405 411411
Calf ADGCalf ADG 1.871.87 1.891.89
Adj 205 d WtAdj 205 d Wt 456456 460460
Cow Wt @ Cow Wt @ WeaningWeaning
914914 929929
Cow BCS @ Cow BCS @ WeaningWeaning
5.15.1 5.35.3
22ndnd Calf Preg % Calf Preg % 9191 9191
33rdrd Calf Preg % Calf Preg % 9494 9292
44thth Calf Preg % Calf Preg % 9696 9696
Developing heifers to 53 Developing heifers to 53 vs 57% of mature vs 57% of mature
weight:weight: Decreased costs $22/headDecreased costs $22/head No differences in pregnancy No differences in pregnancy
raterate No differences in calf No differences in calf
productionproduction Decreased mature weight Decreased mature weight
through 4through 4thth pregnancy diagnosis pregnancy diagnosis
Animals Must Fit The Environment !
When is the When is the appropriate appropriate time to calve time to calve heifers for a heifers for a June – June – calving cow calving cow herd???herd???
Effect of Age and Time Effect of Age and Time on Return to Estruson Return to Estrus
Age of Cow Days after calving40 50 60 70 80 90 100
% Cycling 5 or older 55 70 80 90 90 95 100
2-3 years 15 30 40 65 80 80 90
Crude Protein in Cattle Diets on Northern Great Plains Rangeland
CR
UD
E P
RO
TE
IN, %
0
APR MAY JUN JUL AUG SEP OCT NOV DEC FEB
2
4
6
8
10
12
14
16
18
MethodsMethods
3-year study3-year study MARC II heifers – 50 each yearMARC II heifers – 50 each year Developed to reach 60% of Developed to reach 60% of
mature weight at breedingmature weight at breeding Placed with bulls either August Placed with bulls either August
or September 5or September 5thth – 45 d – 45 d Data collected through 4Data collected through 4thth
pregnancy diagnosispregnancy diagnosis
Developing heifers to Developing heifers to calve before or with the calve before or with the
cow herdcow herdCalvingCalving MayMay JuneJune
Beginning WeightBeginning Weight 402402 403403
Winter GainWinter Gain 1.51.5 1.21.2
Prebreeding WtPrebreeding Wt 703703 727727
Pelvic Area, cmPelvic Area, cm 175175 181181
Cycling before Cycling before breedingbreeding
8989 9292
Pregnant 45 dPregnant 45 d 8888 9393
Precalving WtPrecalving Wt 895895 908908
Precalving BCSPrecalving BCS 5.35.3 5.25.2
Calf birth WtCalf birth Wt 7373 7474
CalvingCalving MayMay JuneJune
Calving difficultyCalving difficulty 1313 00
Actual WWActual WW 396396 327327
Calf ADGCalf ADG 1.751.75 1.631.63
Adj 205 d WtAdj 205 d Wt 433433 409409
Cow Wt @ WeaningCow Wt @ Weaning 910910 910910
Cow BCS @ Cow BCS @ WeaningWeaning
5.05.0 5.05.0
22ndnd Calf Preg % Calf Preg % 7878 8282
33rdrd Calf Preg % Calf Preg % 9595 8787
44thth Calf Preg % Calf Preg % 9797 9595
Developing heifers to Developing heifers to calve before or with the calve before or with the
cow herdcow herd
Developing heifers to Developing heifers to calve with the cow herd calve with the cow herd vs one-month earlier:vs one-month earlier:
Decreased costs $11/headDecreased costs $11/head No differences in pregnancy rateNo differences in pregnancy rate Decreased calving difficultyDecreased calving difficulty Decreased calf WW and adj 205 Decreased calf WW and adj 205
d weightd weight Tended to lower mature weight Tended to lower mature weight
through 4through 4thth pregnancy diagnosis pregnancy diagnosis
Does Fat Does Fat Supplementation Supplementation
Improve Reproductive Improve Reproductive Efficiency?Efficiency?
IntroductionIntroduction
Positive reproductive effects Positive reproductive effects have been associated with fat have been associated with fat supplementation independent of supplementation independent of energy contributionenergy contribution
Increased pregnancy ratesIncreased pregnancy rates Decreased duration of anestrusDecreased duration of anestrus Increased calf vigorIncreased calf vigor
Heifer DevelopmentHeifer Development
Heifers that conceive early in the Heifers that conceive early in the breeding season have a greater lifetime breeding season have a greater lifetime productivityproductivity
(Lesmeister et al., (Lesmeister et al., 1973)1973)
Fat supplemented heifers reached Fat supplemented heifers reached puberty earlier (diet X sire breed puberty earlier (diet X sire breed interaction)interaction)
(Lammoglia et al., 2000)(Lammoglia et al., 2000)
Inconsistencies Inconsistencies (Funston et al., 2000; Howlett et al., 2003)(Funston et al., 2000; Howlett et al., 2003)
Feeding 2 lb of whole Feeding 2 lb of whole sunflower seeds for either sunflower seeds for either 30 or 60 d before PGF did 30 or 60 d before PGF did not improve estrous not improve estrous response or pregnancy rate response or pregnancy rate in beef heifers.in beef heifers.
Linoleic Acid and Age at Linoleic Acid and Age at PubertyPuberty
Heifers fed whole sunflower seeds Heifers fed whole sunflower seeds (5% added fat) from 4 months of age(5% added fat) from 4 months of age
CLA tissue content higher in HF CLA tissue content higher in HF Leptin and insulin not differentLeptin and insulin not different IGF-I lower in HF groupIGF-I lower in HF group Total cholesterol was increased in Total cholesterol was increased in
HFHF No difference in age at pubertyNo difference in age at puberty
Garcia et al., 2003
Fat SourceFat Source
In beef cattle, plant-derived In beef cattle, plant-derived fatty acids appear to have the fatty acids appear to have the greatest impact on reproductive greatest impact on reproductive performance performance
(Burns and (Burns and Filley, 2002)Filley, 2002)
Soybeans are readily available in Soybeans are readily available in NebraskaNebraska
Problems feeding Problems feeding whole soybeans?whole soybeans?
Most research has been with Most research has been with pregnant beef cattlepregnant beef cattle
Heifer development, MO, longer Heifer development, MO, longer WSB were fed, lower the WSB were fed, lower the conception ratesconception rates
Other negative effects reported Other negative effects reported by veterinariansby veterinarians
Why?Why?
Soybean Phytoestrogen Soybean Phytoestrogen AnalysisAnalysis
PhytoestrogenPhytoestrogen ppmppm
GenisteinGenistein 10951095
DaidzeinDaidzein 940 940
GlyciteinGlycitein 100 100
Soybeans in Heifer Diets Soybeans in Heifer Diets of Different Physiological of Different Physiological
MaturityMaturity
ObjectiveObjective
1)1) Investigate the inconsistencies Investigate the inconsistencies associated with fat associated with fat supplementation in heiferssupplementation in heifers
2)2) Determine the effects of Determine the effects of soybeans as the fat source in soybeans as the fat source in heifer diets of different heifer diets of different physiological maturityphysiological maturity
Experiment 1Experiment 1
Objective: Objective: Determine how utilization of Determine how utilization of
soybeans in heifer diets affect:soybeans in heifer diets affect: Cycling statusCycling status Synchronization rateSynchronization rate Conception rateConception rate Pregnancy ratePregnancy rate
Experiment 1Experiment 1
104 crossbred 104 crossbred beef heifers beef heifers 660 lb 660 lb 10 months old10 months old
3 lb whole 3 lb whole soybeans soybeans 4% added fat4% added fat
Experimental Experimental period: 110 dperiod: 110 d
Heifer DietsHeifer DietsDietDiet
Ingredient, % of Ingredient, % of diet (DM)diet (DM)
Control Control (3% fat)(3% fat)
SoybeanSoybean(7% fat) (7% fat)
Corn SilageCorn Silage 48.748.7 54.554.5
Wheat StrawWheat Straw 14.214.2 32.732.7
SoybeansSoybeans 00 10.410.4
Corn Gluten FeedCorn Gluten Feed 13.413.4 00
Brome HayBrome Hay 21.421.4 00
SupplementSupplement 2.32.3 2.32.3
CPCP 11.211.2 10.810.8
TDNTDN 65.365.3 64.264.2
MethodsMethods
Synchronized estrus:Synchronized estrus: MGA (14 d) - PGFMGA (14 d) - PGF22injection on d injection on d
110 (19 d later)110 (19 d later)
Artificially inseminated (AI):Artificially inseminated (AI):
12 hours after visual detection of 12 hours after visual detection of estrusestrus
1 of 2 randomly assigned sires1 of 2 randomly assigned sires
MethodsMethods
Bulls were placed with cows 10 Bulls were placed with cows 10 days after last AI for 60-d days after last AI for 60-d breeding seasonbreeding season
Pregnancy to AI determined by Pregnancy to AI determined by ultrasonography 45 d after last ultrasonography 45 d after last AIAI
ResultsResults
No differences in cycling status No differences in cycling status due to treatment:due to treatment:
((P P > 0.10)> 0.10)
% Cycling% Cycling ControlControl SoybeanSoybean
BeforeBefore 8383 7979
MidMid 9494 9090
PGFPGF 9494 8787
Estrous ResponseEstrous Response
96
81
0102030405060708090
100
Control WSB
Average TimeAverage Time d d ControlControl 2.92.9
WSBWSB 3.23.2
P < 0.05
P = 0.05
Conception and Conception and Pregnancy RatesPregnancy Rates
72 69
94
81
65
90
0102030405060708090
100
Control Soybean
ConceptionPregnancyFinal Preg.
P > 0.10
Experiment 2Experiment 2
Objective: Examine Objective: Examine effects of fat effects of fat supplementation supplementation (soybeans) on (soybeans) on follicle follicle characteristics of characteristics of prepubertal heifersprepubertal heifers
Experiment 2Experiment 2
50 crossbred 50 crossbred heifersheifers 470 lb, 9 mo. old470 lb, 9 mo. old 3 lb soybeans + 1 3 lb soybeans + 1
lb cornlb corn Control = 4 lb DDGControl = 4 lb DDG Experimental Experimental
period = 161 dperiod = 161 d
Experiment 2Experiment 2
Ultrasound guided follicular Ultrasound guided follicular aspirationaspiration
2 injections PGF2 injections PGF22αα 14 d apart 14 d apart 60 h after 260 h after 2ndnd injection (d 147) injection (d 147) Follicle DiameterFollicle Diameter AspirateAspirate
Placed with bulls for 45 d breeding Placed with bulls for 45 d breeding seasonseason
ResultsResults
No differences in No differences in estrous activity due estrous activity due to treatment:to treatment: Sample period 1: 32%Sample period 1: 32% Sample period 2: 84%Sample period 2: 84% ((P P > 0.10)> 0.10)
No difference in No difference in pregnancy ratepregnancy rate
80 88
0
10
20
30
40
50
60
70
80
90
100
Control Soybean
Pregnancy Rate
(P > 0.10)
Experiment 2Experiment 2
Aspirates will be Aspirates will be assayed for:assayed for:
*Estrogen*Estrogen
*Androstenedione*Androstenedione
Follicle Diameter (mm)
11.6
12.2
9
10
11
12
13
Control Soybeans
(P = 0.166)
Experiment 3Experiment 3
Objective: Examine effects of fat Objective: Examine effects of fat supplementation (soybeans) on supplementation (soybeans) on follicle characteristics of follicle characteristics of postpubertal heiferspostpubertal heifers
Experiment 3Experiment 3
20 crossbred20 crossbred virgin heifers virgin heifers 780 lb780 lb
3 lb Soybeans + 1 lb corn3 lb Soybeans + 1 lb corn Control: 4 lb Dried Distillers Control: 4 lb Dried Distillers
GrainGrain Experimental period: 30 dExperimental period: 30 d
Experiment 3Experiment 3
Ultrasound guided follicular Ultrasound guided follicular aspirationaspiration 2 injections PGF2 injections PGF22αα 14 d apart 14 d apart 60 h after 260 h after 2ndnd injection injection Follicle DiameterFollicle Diameter AspirateAspirate
Follicle AnalysisFollicle Analysis
Aspirates will be Aspirates will be assayed for:assayed for:
*Estrogen*Estrogen
*Androstenedione*Androstenedione
Follicle Diameter (mm)
11.5
13.4
9
10
11
12
13
14
15
Control Soybean
(P < 0.07)
Supplementing Soybeans Supplementing Soybeans in Heifer Development in Heifer Development
DietsDiets Decreased synchronization rateDecreased synchronization rate Increased time of synchronized Increased time of synchronized
estrousestrous No significant differences in AI No significant differences in AI
conception or pregnancy rates, conception or pregnancy rates, or final pregnancy ratesor final pregnancy rates
Follicular dynamics????Follicular dynamics????
Heifer Development and Heifer Development and Fat SupplementationFat Supplementation
548 lb, 9 mos; 24 per treatment548 lb, 9 mos; 24 per treatment Fed diets for 113 d; (2% added Fed diets for 113 d; (2% added
fat)fat) Discontinued 1 week before MGADiscontinued 1 week before MGA
%% CONCON COTCOT SBSB SHSH
PubertaPubertall
6060 5353 6969 7171
FSCRFSCR 3737 3838 5757 4242
Howlett et al., 2003 (P > 0.10)