Pregnancy rates of more than 85% can be regularly achieved with yearling heifers that have reached critical weight before mating. Low pregnancy rates and poor calving percentages in mobs of heifers mated as yearlings are usually associated with inadequate liveweight at mating - as liveweight is the most important factor determining the onset of oestrus. The 59 two-year-old calvers produced an extra 51 calves during their lifetime in the herd.
It can be seen that calving first at two years had no effect on cow survival and life span in the herd, virtually no effect on mature cow size, but a large effect on productivity. Summary of lifetime productivityĪverage weaning weight of calves (corrected for calf sex) kg For example, the results of an experiment using Hereford cattle are summarised in the following table: Well-managed heifers calving first at two years have a higher lifetime productivity than heifers calving first at older ages.Īlthough some producers believe that heifers calving at two years will have retarded growth and a subsequent reduction in productivity, a number of long-term experiments have shown that this is not the case. Lifetime performance of heifers calving at two years
There may be less incentive to calve heifers as two-year-olds if seasonal conditions are poor, as extra feed costs may not be offset by the extra return.Įven in poorer seasons, the value of quickened genetic progress must be considered. When returns from beef cattle are good, it is worth bringing heifers into production as early as possible. The main cost of mating heifers as yearlings is the need to feed weaner heifers so that they achieve a minimum liveweight at mating.īritish breed heifers should weigh at least 275-280 kg at joining, while the later maturing European breeds should weigh at least 320 kg.
0 kommentar(er)
