Removing non-rearing ewes from a breeding flock can significantly boost lamb marking percentages and increase on-farm returns through meat and wool sales. Non-rearing ewes are animals that fail to take a lamb from pregnancy scanning through to lamb marking, increasing neonatal mortality rates. The impact of this type of lamb mortality is currently the largest cost to the sheep industry with Meat and Livestock Australia (MLA) estimating losses of $540 million per year.
To maximize lamb survival rates, you need to identify non-rearing ewes and monitor them for future performance. Identify these ewes at, or soon after, marking time as signs of lamb activity are more obvious. As lambs get older and closer to weaning it can be more difficult to identify non-rearing ewes as natural weaning may have started to occur.
To identify non-rearing ewes, check the udder for milk contents and lamb activity. A ewe with a lamb will typically have a udder full of milk, no birth stain on the back of the udder and clean teats from a lamb suckling. A non-rearing ewe, on the other hand, will have a small or unbalanced udder that may be dirty from birth stain and have no signs of suckling. If you are still unsure, non-rearing ewes will not call for a lamb once separated from the flock. If you have made an incorrect udder assessment on a ewe, it should become obvious as they bellow for their lamb.
Once a ewe has been physically examined and there is enough evidence to suggest that it has not reared a lamb, it will need to be identified for future reference. Electronic tags (eID) may be used to put a lifetime trait or note associated against the tag so it can be identified at a later stage. If older ewes are not fitted with eID, a larger tag or an ear notch could be used instead. Once identified these ewes can be closely monitored for future pregnancy scanning results and lost lambs.
Making a cull based on a single year failure is risky as there may be environmental or external factors which caused a lost lamb. Instead, ewes should be monitored for repeated failures for the remainder of their lives. In the event of another lost lamb, consider culling the ewe from the breeding program. This is especially important for younger ewes as there is a greater potential for future lamb production. For older ewes that are nearing the end of their lifetime, culling non-rearing ewes as soon as they are identified could provide an opportunity to lower pressure on pastures and provide a quick source of income, especially with current high mutton prices.
Maximising the number of ewes successfully rearing lambs will improve the efficiency of your flock, making your sheep enterprise more productive and profitable.
