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)