Replacement Heifer Management: A coordinated management concept Richard F. Randle, DVM, MS Beef...
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![Page 1: Replacement Heifer Management: A coordinated management concept Richard F. Randle, DVM, MS Beef Extension Veterinarian University of Nebraska-Lincoln.](https://reader036.fdocuments.us/reader036/viewer/2022062620/5519c8d3550346695e8b49db/html5/thumbnails/1.jpg)
Replacement Heifer Management:A coordinated management concept
Richard F. Randle, DVM, MSBeef Extension Veterinarian
University of Nebraska-Lincoln
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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
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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
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Adapted from Bellows and Short, 1990; Wiltbank, 1990
Reproductive Losses (%)Reproductive Losses (%)
Non-pregnant51%
Gestation11%
Birth - 2 wk33%
2 wk - weaning4%
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Adapted from Bellows and Short, 1990; Wiltbank, 1990
Bred ReplacementsBred Replacements
Failed to conceive or lose calves
35%
Wean calves and rebreed
65%
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Replacement Heifers
• Calve by 24 months of age with minimum
problems
• Give birth to and raise a vigorous, healthy calf
• Successfully re-breed
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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
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Courtesy of Dr. Jeff Ondrak GPVEC
Dr. Jeff Ondrak - GPVEC
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Breeding: Conception
Rebreeding
Postpartum period; lactation
Weaning
Puberty Gestation
Parturition
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Process….
• Selection
• Development
• Procedures
• Monitor
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Heifer Selection• Replacement rate - 10% to 20%
• Select 10% to 20% more
• Age, Size
• Conformation
• Dam performance
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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
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Heifer Development
• Grow
• Attain puberty
• Determine breeding strategy
• Bull selection
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Puberty
• Function of…–Age
• 10 to 12 months• Breed influence
–Weight• 55% to 65% of mature weight
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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
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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
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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
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Target Weight
Breeding Weight - Weaning Weight
Breeding Date - Weaning Date= ADG
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Breeding Strategy
• In order for heifer to calve by 24 months of age she must conceive by 15 months of age
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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
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Breeding Strategy
• Breed heifers to calve 2 to 3 weeks before the cow herd
• Calve the second time in line with the cow herd
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Breeding Strategy
• Natural Service
• Synchronization
• Artificial Insemination
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Procedures• Health
• Pre-breeding
• Pregnancy Examination
• Pre-calving
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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….
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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
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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
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65% 55%
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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
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Identify abnormally small or shaped pelvis
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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.
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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
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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
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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
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Pre-calving Examination
• Perform 30 to 45 days before calving
• Weight and body condition– 85% of mature weight– BCS of 6
• Health
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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
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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
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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
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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.
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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
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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