Fertilization Rate and Early Embryonic Mortality in Ewes in North West Queensland

The extent and nature of prenatal losses up to 20 days post-coitum were examined in three groups of ewes joined at intervals over the period September to December at at a time when ambient temperatures were high (>35”C). Fertilization rates ranged from 72.7 per cent to 80.4 per cent whilst the proportions of abnormal ova noted were similar to those recorded from more temperate areas of Australia. Embryonic mortality post-fertilization was not of great magnitude, the primary cause of prenatal loss to 20 days being fertilization failure.