Replacement Heifer Management:A coordinated management concept

Richard F. Randle, DVM, MSBeef Extension Veterinarian

University of Nebraska-Lincoln

Adapted from (A)Willham, 1973; (B)Melton, 1995

Economic and GeneticImportance of Various Traits

Economic and GeneticImportance of Various Traits

Cow-Calf Fully

Integrated Firm %

Heritability Reference* A B B A Reproduction 20 3.2 1 10 Production 10 2.8 10 40 Product 1 1.0 14 50

From Dearborn et al., 1973; Laster et al., 1979

Heritability of Reproductive Traits

Trait Heritability Age at puberty .41 Weight at puberty .40 First service conception .22 Conception/estrous cycle exposed .27 Failure to conceive .09 Calf born alive .00 Calf alive at 2 weeks .03 Calf alive at weaning -.01

Adapted from Bellows and Short, 1990; Wiltbank, 1990

Reproductive Losses (%)Reproductive Losses (%)

Non-pregnant51%

Gestation11%

Birth - 2 wk33%

2 wk - weaning4%

Adapted from Bellows and Short, 1990; Wiltbank, 1990

Bred ReplacementsBred Replacements

Failed to conceive or lose calves

35%

Wean calves and rebreed

65%

Replacement Heifers

• Calve by 24 months of age with minimum

problems

• Give birth to and raise a vigorous, healthy calf

• Successfully re-breed

Importance of Replacement Heifers

• Dictates future performance of herd– Where will the herd be in 5 years?

• Substantial investment before any return– 30 months minimum before sale of 1st calf

• Highest potential for reproductive problems– Dystocia, calf survival, rebreeding

Courtesy of Dr. Jeff Ondrak GPVEC

Dr. Jeff Ondrak - GPVEC

Breeding: Conception

Rebreeding

Postpartum period; lactation

Weaning

Puberty Gestation

Parturition

Process….

• Selection

• Development

• Procedures

• Monitor

Heifer Selection• Replacement rate - 10% to 20%

• Select 10% to 20% more

• Age, Size

• Conformation

• Dam performance

Heifer Selection Scenarios

• Retain all heifers and breed• Retain all heifers born in 1st half of calving

– Remove top and bottom 10% by size or weight• Retain all heifers born in 1st 30 days

– Remove top and bottom 10% by size or weight

• Calf performance data• Dam performance data

Heifer Development

• Grow

• Attain puberty

• Determine breeding strategy

• Bull selection

Puberty

• Function of…–Age

• 10 to 12 months• Breed influence

–Weight• 55% to 65% of mature weight

from Byerley et al., 1987

Pregnancy Rates of HeifersBred at Pubertal or Third Estrus

Pregnancy Rates of HeifersBred at Pubertal or Third Estrus

% Pregnant

Pubertal 57

Third 78

% Pregnant

Pubertal 57

Third 78

Adapted from Fox et al., 1988

Heifers Optimum Growth Rate for Breeding Herd Replacement Heifers

Frame size

Item 1 3 5 7 9

Optimum wt at 1st estrus, lb 570 670 760 850 950

Mature wt, lb 880 1025 1170 1320 1470

Target Weight

• Determine breeding date based on when you want them to calve

• Determine the target weight for breeding

• Determine the number of days from weaning to breeding

• Determine ADG

Target Weight

Breeding Weight - Weaning Weight

Breeding Date - Weaning Date= ADG

Breeding Strategy

• In order for heifer to calve by 24 months of age she must conceive by 15 months of age

Breeding Strategy

• In order for a cow to calve every 365 days she must conceive by 80 days post calving– Uterine involution– Return to cycling

• Cows average 40 to 60 days

• Heifers average 60 to 80 days

Breeding Strategy

• Breed heifers to calve 2 to 3 weeks before the cow herd

• Calve the second time in line with the cow herd

Breeding Strategy

• Natural Service

• Synchronization

• Artificial Insemination

Procedures• Health

• Pre-breeding

• Pregnancy Examination

• Pre-calving

Health and Vaccination Program

• Advice and guidance of veterinarian– Proper product use– Timing

• Starts at or before weaning– Prebreeding, Pregnancy Exam, Pre-calving

• Focus on diseases that cause reproductive losses and reduced reproductive performance– IBR, BVD, Lepto, Brucella, Campylobacter,

Trichomoniasis, Neonatal diarrhea, Parasites….

Pre-breeding Evaluation• Evaluate weaning to pre-breeding

development

• Average age of the group should be 12.5 to 13.5 months (375 - 410 days)

• Performed 30 to 60 days prior to scheduled breeding program

Pre-breeding Examination• Weight and body condition

– 80 % at 55% of mature body weight

• Pelvic measurement– 150 cm2 or greater

• Reproductive tract score– 50% or greater cycling (RTS 4, 5)

• Conformation and structural soundness

• Health

65% 55%

From Anderson et al., 1991

Reproductive Tract Scores

RTS

Uterine Horns

Ovarian Length (mm)

Ovarian Height (mm)

Ovarian Width (mm)

Ovarian Structures

1

Immature, <20 mm diameter, no tone

15

10

8

No palpable follicles

2

20-25 mm diameter, no tone

18

12

10

8 mm follicles

3

20-25 mm diameter, slight tone

22

15

10

8-10 mm follicles

4

30 mm diameter, good tone

30

16

12

> 10 mm follicles, Cl possible

5

> 30 mm diameter

>32 20 15 Corpus luteum present

Identify abnormally small or shaped pelvis

Adapted from Fox et al., 1988

Neonatal Exposure to Progesterone & Estradiol on Reproductive Tract in Beef Heifers

Age at Treatmentb Responsea Birth Day 21 Day 45 Control SEM

Uterocervical weightc (g)

113.7d

123.5d

101.3d

173.9e

13.9

Myometrial area (mm2)

123.7g

141.8g

111.3g

162.8h

8.5

Endometrial area (mm2)

29.9i

32.4i

37.7i

45.4j

2.7

Gland Density (hits/mm2)

172.2d

380.3e

382.2e

486.9f

48.6

Uterine luminal protein (mg/flush)

2.8d

2.9d

2.3d

4.9e

0.7

aData were collected from cyclic adult beef heifers on Day 12 of induced estrous cycle.

Group means (n = 5) and SEM are presented.bTreated heifers received a single Synovex-C implant sc on designated day of life. Controls were untreated.cWet weight.d,e,f(P<0.01), g,,h(P<0.02), i,j(P<0.09): Means within a row with different superscripts differ.

Pre-breedingIndividual and Summary Data

• Used to evaluate success, identify potential problems and institute management changes

• Pre-breeding analysis– % cycling, nutritional status, structural soundness

• Review breeding management

Pregnancy Examination• Perform prior to 120 days gestation

– determine fetal age

• Weight and body condition

• Distinguish AI pregnancies from natural service pregnancies– withhold clean-up bulls 2 weeks

• Health

PregnancyIndividual and Summary Data

• Used to evaluate success and identify management changes for improvement

• Pregnancy rates, pregnancy histograms, synchronization response, AI conception rates, synchronized pregnancy rates

Pre-calving Examination

• Perform 30 to 45 days before calving

• Weight and body condition– 85% of mature weight– BCS of 6

• Health

Adapted from Patterson and Bullock, 1995

Reproductive Summary

RTS n Weight

(kg)

Pelvic height (cm)

Pelvic width (cm)

Pelvic area (cm2)

Estrous response

(%)

1 61 270a 13.9a 10.9a 152a 54a

2 278 282b 14.1a 11.2a 158a 66b

3 1103 317c 14.5b 11.4b 166b 76c

4 494 333d 14.7c 11.7c 172c 83d

5 728 343d 14.7c 11.7c 172c 86d

Reproductive Performanceby Reproductive Tract Score

RTS Exposed Pregnant Open Preg Rate

1 75 46 29 61

2 1055 854 201 81

3 4504 3911 593 87

4 4912 4322 590 88

5 3675 3261 414 89

TOTALS 14221 12394 1827 87

Randle RF, Patterson DJ, 2005

Reproductive Performanceby Reproductive Tract Score

1st 21 Days 2nd 21 Days 3rd + 21 Days

RTS Exposed Hd % Hd % Hd %

1 75 26 35 13 17 7 9

2 1055 505 48 185 18 164 16

3 4504 2443 54 842 19 626 14

4 4912 2875 59 855 17 592 12

5 3675 2269 62 586 16 406 11

TOTAL 14221 8118 57 2481 17 1795 13

Randle RF, Patterson DJ, 2005

Randle RF, Patterson DJ, 2005

Comparison of pre-breeding weights by RTS in yearling replacement heifers

RTS 1 RTS 2 RTS 3 RTS 4 RTS 5

n 17 113 673 587 612

Mean, (kg) 302 306 308 337 343

Median, (kg) 302 307 297 335 341

Mode, (kg) 264 264 282 318 341

Range, (kg) 192 166 257 277 257

Min, (kg) 213 235 186 218 260

Max, (kg) 405 401 443 495 517

1RTS – reproductive tract score. Heifers evaluated were 350 to 410 d of age and of Angus or predominantly Angus breeding.

NAHMS Survey, 1994

Use of Reproductive Management Technology in Beef Heifers

• CHAPA– 799 operations– 18 top beef states– 70% of U.S. beef

cow/calf operations

Alabama, Arkansas, California, Colorado, Florida, Georgia, Iowa, Kansas, Kentucky, Mississippi, Missouri, Nebraska, New Mexico, Oklahoma, Tennessee, Texas, Virginia, Wyoming

NAHMS Survey, May 1994

Selected Management PracticesUsed on Replacement Beef Heifers

Management Practice Percent of Operations Feed separately Pelvic measurements Reproductive tract scores Breed prior to mature herd Synchronize estrus Artificial insemination Body condition score Weigh Pregnancy test/palpation

32.8 3.0 1.2

12.7 3.0 3.3 4.6 7.9

15.9