Mortality, weight and body measurements at birth of Dairy Shorthorn calves

Abstract

1. Records of mortality of Dairy Shorthorn heifer calves in the N.I.R.D. herd from 1924 to 1946 were analysed and show a total loss of 16·3%. Losses due to abortions amounted to 5·1%, to stillbirths 6·3%, and post-natal losses in calves up to 6 months of age, 4·8%.2. The mean adjusted length of gestation period for 230 Dairy Shorthorn cows was 285·6 days.3. Calves carried longer were heavier at birth, the average increase in weight amounting to 0·91 lb. per day of gestation.4. The adjusted mean birth weight of the calves was 81·68 lb. Bull calves are carried longer than heifer calves by about 1·68 days and they are heavier at birth by about 3·29 lb.5. The birth weight of 111 heifer calves born between 1940 and 1947 was 79·9 lb. as compared with the value obtained before the war of 87·0 lb. for 285 heifer calves.Some factors affecting the weight of the calf at birth were studied; including the effect of artificial mating.