Studies on factors in beef cattle production in a subtropical environment. 1. Birth weight

Abstract

Data from 502 calves from 244 cows during the years 1954-1957 at "Brian Pastures" Pasture Research Station of the Queensland Department of Agriculture and Stock were analysed. The effects of sex, year of birth, age of dam, weight of dam and time of birth on birth weight were evaluated. The mean birth weight of all calves was 70·4 lb. The male calves weighed 4·7 lb. more than the female calves, the difference being significant. Significant year differences were recorded due to the marked lowering of birth weight following the 1957 drought. First-calf heifers gave birth to calves which were 4 lb. lighter than those of mature cows. Weight of dam was significantly related to birth weight and was associated with approximately 6 per cent. of the variation in birth weight of the calf. Time of calving, in a 3-month calving period, also was significantly related to birth weight but was only associated with 3 per cent. of the variation in the birth weight of the calf.