Replacement Heifer Management: A coordinated management concept Richard F. Randle, DVM, MS Beef Extension Veterinarian University of Nebraska-Lincoln

Economic and Genetic Importance of Various Traits Adapted from (A)Willham, 1973; (B)Melton, 1995

Heritability of Reproductive Traits From Dearborn et al., 1973; Laster et al., 1979

Reproductive Losses (%) Adapted from Bellows and Short, 1990; Wiltbank, 1990

Adapted from Bellows and Short, 1990; Wiltbank, 1990 Bred Replacements Adapted from Bellows and Short, 1990; Wiltbank, 1990

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

Postpartum period; lactation Breeding: Conception Puberty Gestation Rebreeding Weaning Parturition Postpartum period; lactation

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 Calf performance data Dam performance data

Heifer Development Grow Attain puberty Determine breeding strategy Bull selection

Puberty Function of… Age Weight 10 to 12 months Breed influence 55% to 65% of mature weight

Pregnancy Rates of Heifers Bred at Pubertal or Third Estrus % Pregnant Pubertal 57 Third 78 from Byerley et al., 1987

Heifers Optimum Growth Rate for Breeding Herd Replacement Heifers Adapted from Fox et al., 1988

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 = ADG 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%

Reproductive Tract Scores From Anderson et al., 1991

Identify abnormally small or shaped pelvis

Neonatal Exposure to Progesterone & Estradiol on Reproductive Tract in Beef Heifers 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. Adapted from Fox et al., 1988

Pre-breeding Individual 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

Pregnancy Individual 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 Adapted from Patterson and Bullock, 1995

Reproductive Performance by 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 Randle RF, Patterson DJ, 2005

Reproductive Performance by Reproductive Tract Score 1st 21 Days 2nd 21 Days 3rd + 21 Days RTS Exposed 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 59 855 592 12 5 3675 2269 62 586 406 11 TOTAL 14221 8118 57 2481 1795 Randle RF, Patterson DJ, 2005

Comparison of pre-breeding weights by RTS in yearling replacement heifers 17 113 673 587 612 Mean, (kg) 302 306 308 337 343 Median, (kg) 307 297 335 341 Mode, (kg) 264 282 318 Range, (kg) 192 166 257 277 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. Randle RF, Patterson DJ, 2005

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, 1994

Selected Management Practices Used on Replacement Beef Heifers NAHMS Survey, May 1994