Prediction of conception rate in extensive beef herds in north-western Australia. 1. Seasonal mating and improved management

摘要: Statistical models for conception rate were developed using data collected at a mid dry season (August-September) muster from controlled-mated and supplemented herd of 900 Brahman cross cows Mt Bundey 1980-84. Average rates 74% maidens, 25% first-lactation cows, 51 % 4-10-year-old lactating 54% >10-year-old 96% non-lactating cows. Although year effects dominated, they partially explained by severity the consistent across levels other factors. Pregnant maiden heifers weighed 13 kg more than non-pregnant ones end mating, after allowing weight fetus gravid uterus. Conception was not affected month calving, adjusted or condition score, possibly because narrow ranges in these factors based on selection. For mature main calving (+11% September to -16% December later), previous lactation (+6% having reared calf), (-16% 350 kg) score (-17% backward store +16% good condition). Corresponding aged +14% -19% later +8% previously rearing calf, -24% +23% The high corresponded with liveweights scores. A low cost, practical implementation is status season, pregnancy diagnosis added next stage. Reproductive classes could be segregated this basis improved management nutrition gain an economic return capital invested cattle control.