Crossbreeding with a tropically adapted

Abstract

Context Cattle producers with Brahman herds considering crossbreeding with a tropically adapted Bos taurus breed would like to know how the females retained for breeding are likely to perform. Currently, there is little relevant information available on their performance in the harsher regions of northern Australia. Aims This study aimed to evaluate the performance of F1 Senepol × Brahman (F1 Senepol) females in a harsh north Australian environment by comparing them with Brahmans. Methods The performance of four year groups of Brahman (total n = 499) and F1 Senepol (total n = 317) heifers was compared in the Katherine region (NT, Australia) using measures for growth, reproduction and survival. Heifers were first mated as 2-year-olds and the study concluded when the oldest year group was 9.5 years old. Cattle were mustered twice a year for data collection and weaning of calves. Key results F1 Senepol females were heavier (P < 0.001) than Brahmans at weaning (+25 kg) and at each subsequent muster. Mature F1 Senepol cows were on average 50 kg heavier (P < 0.001), 2 cm taller (P < 0.001) and had 2.4 mm lower P8 fat depth (P < 0.001). The mean pregnancy rate was higher in F1 Senepol maiden heifers (F1 Senepol 89.4%, Brahman 70.0%, P < 0.001), calf loss was higher for Brahman heifers calving for the first time (Brahman 14.4%, F1 Senepol 6.0%, P < 0.01), but there were no significant differences in these measures between breeds at any other ages. The average annual weaning rates for the breeds were similar (F1 Senepol 59%, Brahman 57%), as was the mean annual female liveweight production (change in female liveweight plus weight of calf weaned). Average weaner weights were significantly heavier from F1 Senepol for first lactation heifers and 5.5-year-old cows (by 6 and 10 kg, respectively, P < 0.05), but only slightly heavier in all other years. There were no significant differences in cumulative mortality rates, for year groups or overall, between breeds. Conclusions This study found that F1 Senepol heifers outperformed Brahman heifers, and that mature cow performance of the breeds was similar. Implications These findings should reassure north Australian cattle producers who are considering crossbreeding Brahmans with a tropically adapted Bos taurus breed that the performance of crossbred breeder herds will be similar to that of Brahmans.