Effect of pre- and post- natal nutrition on the growth of beef cattle I. The effect of nutrition and parity of the dam on calf birth weight

Abstract

The influence of submaintenance (low plane) nutrition during the last trimester of pregnancy, and parity of the dam, on calf birth weight was studied in Hereford cows.The submaintenance ration (3.5 kg Rhodes grass hay per head per day) significantly (P < 0.01) reduced the mean calf birth weight by 6.8 kg to 24 1 kg, and the mean length of gestation by 5.4 days to 277.3 days, compared with an above-maintenance (high plane) ration (3.5 kg each of Rhodes grass hay and barley grain per head per day). Dam nutrition, however, did not influence the number of retained placentae, calf mortality, or the incidence of dystocias. Dam parity did not significantly influence calf birth weight or length of gestation, but significantly (P < 0.05) reduced the number of retained placentae of second parity cows. There were no significant differences between sexes in mean birth weight or mean gestation length. The regression of calf birth weight on dam weight just prior to calving was significant (P < 0.05) for high plane cows: y = 20.248 + 0.023x, r = 0.40. The regression of calf birth weight on length of gestation was significant for both high(P < 0.05) and low(P < 0.01) plane cows: y = –28.343 + 0.210x, r = 0.40, and y = -41.015 + 0.235x, r = 0.42 respectively.