Gestation of cattle in the sub-tropics, with special reference to the birth weight of calves

The gestation period of Afrikaner cattle and their crossbreds is longer than that of European-type cattle, but the Afrikaner produces a smaller calf at birth. In general, an increase in the period of pregnancy results in heavier calves being born, and male pregnancies last longer than those producing heifer calves. No significant effect was produced by the dams age in respect of either the duration of pregnancy or the birth weight of calves. The sire may influence both the pregnancy period and the weight at birth of calves, but no seasonal effects were evident.