Characterization of Biological Types of Cattle I. Dystocia and Preweaning Growth

Abstract

Gestation length, birth weight, dystocia level, calf mortality, preweaning growth and 200-day weight were studied for 2,368 calves out of Hereford and Angus cows and by Hereford, Angus, Jersey, South Devon, Limousin, Charolais and Simmental sires. Charolais and Simmental crosses had faster preweaning average daily gains (ADG) and were heavier at 200 days, but also had larger birth weights and more dystocia. South Devon and Limousin crosses were similar in 200-day weight to Hereford-Angus crosses, but were intermediate in birth weights and more like Charolais and Simmental crosses in level of calving difficulty. Jersey crosses were lightest at birth and 200 days and experienced much less dystocia than other crosses. Gestation length was longest for Limousin (288.1 ± .4 days) and shortest for Jersey (281.8 ± .5 days) and Hereford-Angus (282.9 ± .4 days) crosses. Preweaning relative growth rate was highest for Jersey, intermediate for Hereford-Angus and lowest for South Devon, Limousin, Charolais and Simmental crosses. Hereford by Angus heterosis was a significant effect for birth weight (.9 kg), 200-day weight (8 kg), ADG (.04 kg/day) and calf survival from birth to weaning (5.1%). Dystocia level increased linearly with birth weight both across and within breed groups. Averaged over all dam ages, each 1 kg increase in birth weight within a breed group increased calving difficulty by 1.63 ± .20%. Calf death losses within 24 hr postpartum were 3.7 times higher in calves experiencing difficulty at birth than those born without difficulty (11.5 ± 1.0% vs 3.1 ± .7%). Calving difficulty did not influence (>.05) calf survical from 24 hr postpartum untl weaning. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.