Beef production from the dairy herd: calving performance of cows

Abstract

Data are reported on the calving performance of cows in beef production trials in three successive calvings of South Auckland herds. The main comparison of Friesian, Hereford, and Charolais sires over the Jersey cow is supplemented by information on the Friesian cow mated to these three sire breeds and on straightbred Jersey and straightbred Angus calvings. Overall, 81% of calvings were unobserved. Eight percent of all calvings, or 45% of observed calvings, were assisted. Jersey and Friesian cows required more assistance when calves were sired by Charolais and Friesian sires, and least when Hereford sires were used. Cow mortalities at calving time were greatest for Jersey and Friesian cows in-calf to Charolais sires. Perinatal calf mortalities accounted for 3.5% of all calves born, with a greater mortality of calves by Charolais sires than other breeds. Calves assisted at birth were heavier than those from unassisted calvings, but gestation lengths did not differ significantly. Calves dying at birth had a shorter gestation period and were lighter than surviving calves. There were significant sire and farm effects on birth weight and gestation length of Jersey crossbred calves, and age of dam significantly affected birth weight but not gestation length. Bull calves had longer gestation periods and were heavier at birth than heifers. Sire breed affected calf birth weights in the descending ranking order of Charolais, Friesian, Hereford, and Jersey. Purebred Angus calves were similar in birth weight to Hereford × Jersey crossbreds. Friesian cows produced heavier calves than Jersey cows. Gestation periods were longest for calves with Charolais sires; those sired by the Hereford were next longest; and Friesian and Jersey sire breeds had the shortest gestations. Heritabilities of birth weight and gestation length were calculated as 0.31 and 0.12 respectively. Results are discussed in relation to beef breeding programmes.