Understanding and improving heifer fertility in the Northern Territory

Summary

This project established the relationship for both pre joining weight and fat depth (condition) with; pregnancy rates in high grade Brahman maiden heifers (joined both as yearlings and as two year olds) and subsequent re-conception rates in first calf heifers in the Northern Territory. The charts developed showing the likely conception rates from different joining weights will be useful management tools for cattle producers and advisors. Various management strategies aimed at increasing heifer productivity were researched. It was found that: 
-Feeding pre partum protein supplements to first calf heifers in the VRD was a reliable method of increasing re-conception rates (by an average of 42%) but was not always cost effective. 
-Feeding pre partum protein supplements to first calf heifers grazing fertilised and improved pastures in the Douglas Daly region did not increase re-conception rates. 
-Current genotypes of high grade Brahman heifers from NT cattle stations were too late maturing to give high pregnancy rates from yearling mating (the average pregnancy rate was 33%). 
-Preliminary economic analysis showed that there was a small positive cost benefit when larger (190-260 kg) Brahman weaner heifers were transported to the Douglas Daly region for yearling mating compared to mating them for the first time as two year olds in the VRD.