Genetic and Environmental Influence on Age at First Calving of the Kenya Sahiwal Cattle

Abstract

Data on age at first calving were obtained from 937 heifers born between 1967 and 1981 in the National Sahiwal Stud. The breeding pattern was such that births occurred in all months throughout the year, although not in equal proportions. Calves were separated from their dams immediately after birth, weighed and bucket-fed colostrum in the first week and whole milk thereafter at a rate of 10% of the body weight. Calves were weaned at 12 weeks at an average weight of 55 kg. After weaning, heifers were grazed on natural pastures consisting of star grass (Cynodon plectostachyum) and Kikuyu grass (Pennisetum clandestinum). There was a strong seasonal effect. Pastures were of good quality in the wet seasons (April-June and October-December), but deteriorated and were of low nutritive value in the dry seasons (January-March and July-September). Heifers were grazed in paddocks supplied with water. Mineral licks were provided ad libitum when available. Dipping was done weekly using acaricide solution to control ticks and vaccinations against foot and mouth, black quarter and anthrax diseases were undertaken yearly.