Research Project -2009

Lamb survival within Australia averages approximately 80%, a figure which suggests that there is great room for improvement. However, previous studies have highlighted that even well managed flocks may not exceed survival rates of 85%. Similar outcomes identified within the Lifetime Wool Project which showed when ideal management guidelines are followed, twin survival still only averages around 60%. These results suggest that tools in addition to management are required to maximise lamb survival rates.

Breed differences in lamb survival have been shown in a vast number of studies suggesting that it is under genetic control. The direct heritability of lamb survival has been estimated as being between 0 and 0.11, thus if it is selected upon genetic progress will be slow. A suggested means of overcoming this is to use indirect selection on a trait that has a higher heritability and is genetically correlated with lamb survival. The three main causes of lamb mortality post partum are starvation, exposure and mismothering. Cold resistance in the lamb has an estimated heritability exceeding 50%, thus this trait has been suggested as a viable means of increasing survival rates.

Perendale sheep are known for their hardiness as they were bred for low input farming in New Zealand. This breed exhibits high lambing rates, a factor of easy lambing, increased maternal ability and increased survival in rough conditions. As such, Perendales were selected for this investigation into cold resistance, in which the breed will be compared to another known for lower lamb survival, the Merino. This project aims to identify clear breed, and thus genetic differences (lamb shape, hormone levels, brown fat quantity and activity) in response to cold exposure in the lamb.The project is being conducted by PhD student, Kate Lennon at The University of Adelaide in conjunction with The Sheep CRC and South Australian Research and Development Institute.