Abstract:
The performance of heifers at their first (maiden heifers) and second matings (first lactation heifers) was recorded between 2003 and 2008 to establish current heifer fertility levels on 14 commercial cattle properties in the Northern Territory (NT). Pregnancy rates in maiden heifers (joined first at ~2 years of age) were generally adequate (>75%) to produce enough pregnant replacement breeders. Pregnancy rates in first lactation heifers were often very low (<20%) due to the low liveweight of heifers between calving and weaning. However on properties where first lactation heifers were in good condition at this time, pregnancy rates were high (>70%). Calf loss between pregnancy diagnosis and weaning in first lactation heifers was often high (>30%). The average of the calf loss figures from all the herds studied was 22%.