Growth rates of British breed calves in central Australia

Abstract

Data were collected on 2649 Shorthorn and Hereford calves under six months old at three sites in central Australia between 1970 and 1976. Growth rates averaged 0.59 kg day-1 over the six-month interval after the calves were tagged, and 0.46 kg day-1 in the following six-month interval. There were significant differences between sites. Regression analysis showed the rate of growth was significantly affected by season, sex and forage abundance. Steers outgained heifers by 0.06 kg day-1 in the first interval (about 6 to 12 months old), and by 0.11 kg day-1 in the second interval (about 12 to 18 months old). Calves born in autumn and spring had the best growth rates. Growth rates up to 0.85 kg day-1 during a period of good forage conditions are comparable with rates of gain on improved pasture in temperate higher rainfall areas of Australia. Growth rates were highest but most variable on the light soiled site with mainly ephemeral forage, lowest at the mulga-perennial grass site and were least variable at the site with mixed annual and perennial forage. This suggests that modified nomadic use during good seasons would be the most effective use of range communities with variable productivity.