An evaluation of cattle types for north-western Australia

Abstract

An evaluation of calving rate and cow mortality in the Kimberley region of Western Australia was made for 6 breeder groups: Shorthorn, Brahman, F1 Brahman x Shorthorn (F1BS), F1 Africander x Shorthorn (F1AS), F, Brahman x Shorthorn (F2BS), and F2 Africander x shorthorn (F2AS). From these 6 breeder groups, 8 steer lines were produced: Shorthorn, Brahman, F1BS, F2BS, F3BS, F1AS, F2AS, and F3AS. These were evaluated for calf survival, calf growth, steer mortality, steer growth, and steer carcass weight. There were significant (P<0.001) year and breed effects on calving rate. F1BS and F1AS showed the highest calving percentage, with corrected means of 60 and 61% for the whole herd and 67 and 66% when 15-month-old heifers were excluded. The calving rate in F2BS dropped to 49%, while that in F2AS was maintained at 67%. Few cows died in any group and it was not possible to detect differences between breed types. Likewise, few steers died after 12 months of age. The lowest mean weaning weight of 116 kg in July at 6 months of age was recorded for Shorthorn calves; the highest was recorded for F2BS at 174 kg. However, the advantage was not maintained until November when the calves were 10 months old. Brahman and F1BS had superior growth rates from weaning to 10 months. There were significant (P<0.001) breed and year effects on steer liveweight at all weighing dates. After the first November weighing, Brahman and F1BS made the greatest liveweight gain. All breeds lost weight in the second dry period. At 27 and 39 months, F1BS steers had the heaviest carcass weights of 222 and 300 kg. F2AS and F3BS steers had the lowest carcass weights at both times (174 kg at 27 months and 22 kg at 39 months).