Performance of Holsteins that originated from embryo transfer or twin births

1. Performance of Holsteins that originated from embryo transfer or twin births H.D. Norman, J.R. Wright*and R.L. Powell Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350 Abstr.W89 Means for Holstein twin cows with DHI milk records and their non-twin full sisters RESULTS INTRODUCTION • Preferential management of embryo transfer (ET) animals could potentially cause bias in genetic evaluations. • Previous studies have indicated that the rate of twin births may be increasing. RESULTS RESULTS (cont.) Twins Full Sisters Standardized trait: Milk (kg) 10,050 10,161 Fat (kg) 366 371 Protein (kg) 298 301 SCS 3.1 3.1 Productive Life (mo) 26.3 26.7 Yield deviation: Milk (kg) -500 -407 Fat (kg) -17 -12 Protein (kg) -14 -11 PTA: Milk (kg) -186 -170 Fat (kg) -6 -5 Protein (kg) -2 -2 SCS 3.1 3.1 Productive Life (mo) 0.0 0.0 OBJECTIVES • Compare the performance of ET Holsteins to their non-ET full sibs. • Compare cows from multiple births (twins, triplets) to their single birth full sibs. • PA of cows recorded from twin births was nearly identical to the population mean with a difference of only 3 kg for milk. • PA of bulls recorded from twin births was less than bull population mean by an average of 138 kg for milk. • Yield deviations of twin cows were lower than their non-twin full sibs by 93, 5, and 3 kg for milk, fat, and protein, respectively. • Average PTAs of twin cows were lower than their non-twin full sibs for milk and fat but the same for protein, SCS, and PL. DATA • ET • 293,033 females and 129,394 males with pedigree records. • 185,104 cows and 26,238 bulls with Parent Average (PA) records. • 10,277 cows and 3,512 bulls with PTAs also having non-ET full sibs with PTAs. • Twin (all multiple births; twins, triplets) • 684,329 multiple birth code females with pedigree records and 11,446 multiple birth code males with pedigree records. • 301,434 multiple birth code cows and 769 multiple birth code bulls with PA records. • 6,514 multiple birth code cows and 57 multiple birth code bulls with PTAs also having full sibs with PTAs. CONCLUSIONS • Numbers of ET animals peaked in 1993 and is currently declining. • Numbers of cows coded twin (multiple birth) has increased during the last 25 years. • PA of ET cows and bulls was superior to the population mean for milk, fat and protein. • PA of bulls coded twin (multiple birth) was less than population mean while PA of cows was nearly the same. • ET cows were nearly identical to their non-ET full sisters for all traits indicating no preferential treatment. • Cows coded twin were out-performed by their non-twin full sibs and stayed in the herd for an average of .4 mo less. Means for Holstein ET cows with DHI milk records and their non-ET full sisters ET Full Sisters Standardized trait: Milk (kg) 10,570 10,565 Fat (kg) 387 390 Protein (kg) 315 316 SCS 3.1 3.1 Productive Life (mo) 26.9 26.3 Yield deviation: Milk (kg) -287 -277 Fat (kg) -6 -3 Protein (kg) -6 -5 PTA: Milk (kg) -106 -107 Fat (kg) -2 -1 Protein (kg) -2 -2 SCS 3.1 3.1 Productive Life (mo) 0.3 0.3 • PA of ET cows was superior to cow population mean by an average of 133 kg for milk. • PA of ET bulls was superior to cow population mean by an average of 339 kg and bull population mean by 80 kg for milk. • Productive Life was .6 mo longer for ETs than for their non-ET full sib sisters. • PTAs for ETs and their non-ET full sib sisters were nearly identical.