Perinatal deaths among calves in a crossbred dairy herd

Abstract

SUMMARY An analysis has been made of still-births and difficulties at parturition in a dairy herd in which purebreds and crossbreds of Friesian, Ayrshire and Jersey origin were kept. There were 2,049 calvings including 28 involving twins. Purebred heifer dams produced 14·7% dead purebred calves (mostly Friesian and Jersey) and 6·4% dead crossbred calves (P < 0·05). For older dams the corresponding values were 2·4% and 3·6% (P > 0·05). Losses were smaller with crossbred dams. Crossbred heifer dams (two-breed crosses) with 6·5% dead calves exceeded older crossbreds with 1·9% dead calves. Three-breed crossbred dams gave similar results (8·2% and 1·2%). An intermediate size of cow of second or later parity was associated with the lowest mortality. Friesian and Hereford sires, the calves by which were heavier than those by Ayrshire and Jersey sires, were associated with greater losses than were the latter but this applies to heifer dams and not to the same extent if at all, to older dams. Of 52 parturitions described as difficult, 31 resulted in dead calves. Malpresentation accounted for 32 cases; the majority of these were ‘hindfeet first’. Friesian and Hereford bulls sired a higher proportion of the calves involved in difficult cases than Ayrshire and Jersey sires.