157 - Comparison of Reproductive and Early Growth Performance of an F1 USDA Prime Yield Grade One Carcass Clone Sire and an Industry-leading Purebred Sire in the Beef X Dairy Production System

Abstract: The objectives of this research were to determine if an F1 USDA Prime, yield grade 1 sire produced from the WTAMU PrimeOne Project (Sire A) was a competitive sire for producing dairy composites when compared to a purebred Angus sire (Sire B), and to evaluate any subsequent reproductive impact of sire on dam. Dairy cows (n = 1,930) were artificially inseminated resulting in 763 pregnancies with 564 births and 536 live calves. Data was collected at a large commercial dairy and analyzed using SAS 9.4 with sire as fixed effect; lactation, breeding technician and services per conception were random effects. Individual animal was experimental unit (n = 536). Conception rates were 40% for Sire A and 31% for Sire B (P ≤ 0.01). Average gestation length (GL) was 284-d and 280-d for Sire A and B, respectively (P ≤ 0.01). Calves by Sire B reported lower average birth weight (BW) than those by Sire A (P ≤ 0.01) with no difference in calving ease score (CE) (P = 0.24). There was no difference in 60-d (P = 0.58) or 120-d calf weights (P = 0.47). However, calves by Sire B reported higher average daily gains at both 60- (0.61 and 0.58 kg; P ≤ 0.01) and 120-d (0.70 and 0.67 kg; P = 0.03). Sire had no effect on morbidity (P = 0.62) or mortality (P = 0.25). Post-partum interval (PPI) and time from first estrus to conception were not different between sires (P = 0.19; P = 0.14). BW and CE did not affect PPI or time from first estrus to conception. Data from this trial indicates the cloned progeny sire increased conception rates, but the purebred Angus sire was more favorable for GL, BW and progeny growth performance. Neither sire negatively impacted subsequent reproductive performance of the dam.