Comparative drought resistance of Bos indicus and Bos taurus crossbred herds in Central Queensland. 1. Relative weights and weight changes of maiden heifers

Abstract

Observations were made during a drought in Queensland in 1969 of the comparative weight changes of Brahman X British (BX), Africander X British (AX), and British X British (SH) crossbred heifers which were grazed together under field conditions at the National Cattle Breeding Station 'Belmont', Queensland. The animals were weighed in February and October, 1969, and in January 1970. At all weighings the BX heifers were significantly heavier than both the AX and the SH heifers and the AX were significantly heavier than the SH. From February 1969 to October 1969, when nutritional conditions were most severe, the mean weight loss of the breeds was 42.1 kg. Breed differences in absolute weight losses were not significant but were least for the BX. When the weight losses were adjusted for differences in initial weight, the BX lost 34.9 kg, the AX lost 39.3 kg and the SH heifers lost 50.5 kg. The difference between the Zebu crossbreds (AX and BX) was not significant. From October 1969 to January 1970 the pasture conditions improved and the mean gain of the breeds was 52.1 kg. The BX heifers gained 55.8 kg, 7.4 kg more than the SH heifers. From February 1969 to January 1970, BX and AX heifers gained 12.0 kg and 8.2 kg respectively more than the SH heifers (3.7 kg) ; the difference between the Zebu crossbreds was not significant. Purebred Brahman and Africander heifers lost less weight than any of the crossbreds from February 1969 to October 1969 and made only slightly lower gains from October 1969 to January 1970. Overall gains from February 1969 to January 1970 were highest in the purebred Brahmans. Some possible reasons for the differences in breed performance are advanced.