Nutritional management of heifers in northern Australia

With over 14 million head of cattle, the north Australian beef industry (north of 26°S) comprises 57% of the Australian cattle population (MLA 2003). The majority (85%) of properties in this regior are breeding enterprises in which breeder fertility is critical for profitability. The turn-off age of cattle has decreased from 4-5 years of age to 1-1.5 years of age, potentiating the impact of breeder fertility on profitability. Although significant improvements in reproductive efficiency have occurred in northern Australia over the last twenty years, reduction in age of puberty and, improvement in the rate of reconception of heifers is possible. Most heifers in northern Australia are first mated at two years of age. Breeder lifetime productivity could be improved by mating heifers at one year of age. Reconception rates for yearling and 2-year-old heifers can be as low as 25%. Recent work in northern Australia suggests that these inefficiencies can be overcome with the right combination of nutrition, genetics and management.