A Seasonal Mating System for Beef Cattle in Central Queensland

It has been shown by a number of workers that seasonal mating is desirable in the Queensland beef industry because of its effect on calf growth, and the Iiveweight of breeding cows. Sutherland (1961) reported that calves born following an October to December mating were approximately 45 kg heavier at 270 days of age than were calves born following a January to June mating. In addition, Stubbs ( 1966) reported an adverse effect on the liveweight of cows which suckled calves over the winter-spring period. Cows from which calves were weaned in May and June had a liveweight advantage of 26 to 40 kg compared with cows which suckled calves until August and September. Alexander (196,s) showed that weaning of calves at eight months of age was preferable to weaning at six months of age in terms of liveweight, irrespective of post-calving treatment to 104 months of age. It would appear, then, that ideally calves should be at least eight months of age when weaned at the time of pasture deterioration in April and May (Gunn 1967; Perry 1968), thereby maximizing weaning weight and conserving the Iiveweight of breeders over the dry season. In order to satisfy these requirements cows should conceive from October to December and calve from July to September, and breeding herd management should be aimed at maximizing conceptions over the chosen period.