Reproduction in farmed red deer. 2. Calf growth and mortality

Abstract

SUMMARYThe sex and number of calves born to a breeding herd of red deer kept under farm conditions are analysed together with information on mortality and on growth rate of the calves until weaning in September–October. The results showed some anomalous deviations of the sex ratio from a 50:50 expectation. Birth weight was related to the weight of the hind at the time of the rut, and so too was the subsequent daily rate of gain of the calf. Stag calves weighed more than hind calves and there was no effect of age of hind on birth weight once weight of hind had been discounted. Mortality was divided into two components; perinatal mortality included stillbirths, deaths at parturition and during the first 24 h of life and an unidentified mortality representing failure to find a calf although the hind had calved. Postnatal mortality was defined to include all deaths from after 24 h of life to weaning. Mortality was related to the weight of the calf at birth, being 100 % for calves weighing less than 4·0 kg and declining to 5 % for calves weighing 6·0–7·0 kg. The data are discussed and the effect of size of hind at the time of the rut on her fertility, the time at which she calves, the birth weight and growth rate of her calf and its survival rate are combined to estimate the annual number of viable weaned calves and the total weight of calves produced by herds of hinds of different weights. An increase in hind weight of 50 % (from 60 to 90 kg) results in a doubling of the number of calves born and surviving to September and an increase in the weight of the calf crop by 160%. Reasons are given to suggest that total calf mortality could be reduced to 7 %.