Factors affecting birth weight and performance to weaning of beef calves in the dry tropics of north Queensland

Abstract

Data from 533 calves from 321 Shorthorn cows at 'Swan's Lagoon', north Queensland, were analysed by the least-squares method. Calves were sired by either Sahiwal or Brahman bulls. Birth weights, growth rates and corrected 180-day weights were comparable in Brahman and Sahiwal cross calves. Age of dam had a significant effect on performance with cows 5-8 years and 9+ years producing heavier calves than cows 3-4 years of age. Calves born early in the season were significantly superior to calves born later and males outperformed females throughout, being 8-9 per cent heavier at 180 days. Pre-calving weight of the cow was positively correlated with calf growth rate and 180 day weight. Calf gains were inversely related to cow gains from birth to weaning. Calf birth weight was significantly correlated with calf growth rate and 180-day weight.