Calving performance and mortality of Shorthorn cattle on a property in north Queensland.

Five groups of shorthorn cows each mated for nine weeks at five different periods each year for the years 1963 to 1966. There was no consistent pattern in the calving percentage of the mating groups over the period. In 1965, the group calving in April-May gave the best calving performance while in 1966, the September-October group was superior and, in 1967, the November- December group was superior. Foetal wastage from pregnancy diagnosis to calving averaged 6 per cent of matings and only in 1966 was there any association between calving group and it. There was no significant difference in mortalities of cows or calves between calving groups but there were significantly higher mortalities in cows in 1965, a drought year. I.