Weaning marks the beginning and the end of the ewes yearly production cycle. It is the time that we can measure the true performance of the ewe flock using the key performance indicator (KPI) kg of lamb weaned per ewe mated.
Top flocks should be achieving at least 40kg lamb weaned / ewe mated1.
Weaning should not occur at exactly the same time every year, rather it should be a decision that is made based on the conditions that are occurring at the time each year.
There are five questions you should ask yourself when you need to make the weaning decision. They are:
Are the ewes gaining weight or losing weight?
Do the ewes have plenty of milk for the lambs, how big are their udders?
Are the lambs growing well on the ewes?
Are the ewes and lambs competing for feed?
Do you have high quality feed for the lambs to wean onto?
Ewe Body Condition
Ideally ewes should already be at their optimal mating body condition by weaning. This means you only need to feed them at a level that maintains their body condition in the period from weaning to mating, and the additional feed saved can go into lamb fattening.
Weaning is an ideal time to body condition score the ewe and pull off the lighter ewes for preferential feeding. There is nothing on a sheep and beef farm that will give you a better return for the feed consumed than taking a BCS 2 ewe and feeding her up to be BCS 3 before mating or lambing2.
Lamb Growth Rates
Lambs will go through a weaning growth check when separated from the ewe. How big that check in growth is will depend on the amount of the lamb’s diet that is still based on milk.
Single lambs grow at about 35g/day faster than twins in late lactation due to higher milk intake, and generally take a bigger weaning check than twin lambs. By weaning, singles will be 3-4kg heavier and closer to slaughter weight. As a result most single lambs should be left on the ewe till slaughter.
Weaning and its Effect on Feed Supply
The decision on when to wean can have a large impact on your feed supply.
If feed is abundant, a late lactation ewe that is growing and milking well can have almost double the requirement for feed intake to a weaned ewe (e.g. 2kg Dm/day v 1kg Dm/day)3. Therefore, if you wean too early when you have an abundance of feed, you will likely lose control of your feed quality.
If feed is limiting, and a lactating ewe is growing and milking poorly, a decision to wean earlier should create more feed, however, the overall feed demand from the ewes will only decrease by a max 0.5kg Dm/day3. This means you will likely need to take other measures as well (i.e. sell some stock) to balance up the feed supply and demand in preparation for the next mating season.
Beef and lamb NZ. Ewe body condition scoring handbook. May 2013.
Litherland, A. Bryant, J. Chicota, R. The weaning decision. Report prepared for meat and wool NZ by Agresearch 2007.