Production responses in selenium supplemented sheep in northern New South Wales. 1. Infertility in ewes and associated production

Responses in fertility after selenium supplementation of breeding ewes in northern New South Wales were examined. The treatment (5 mg selenium) was given orally as sodium selenite three weeks before joining, and responses were measured in terms of the proportion of ewes lambing. A total of 14 experiments was conducted on eight commercial properties over three years. In some flocks the effect of selenium supplementation on wool production and liveweight was also assessed. All sites were in areas of likely selenium deficiency. Selenium supplementation significantly increased the proportion of ewes lambing in 5 sf the 14 flocks studied but responses were quite variable between properties and years. The effect of supplementation on greasy wool production was small, but significant in two of the seven flocks measured. The treatment did not affect liveweight.