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When Should You Wean Lambs? Advice Before and After

15 June 2015


Sheep farmers should make the decision to wean lambs based on ewe body condition, feed availability and lamb growth rates.

when to wean lambsThis is according to AHDB Beef and Lamb which says from the eight week old period, a lamb's energy intake is greater from grass than from milk.

At this point the competition between ewes and lambs for high-quality grass reaches a critical point.

Grazing management and grass growth will differ year on year so the ideal weaning date cannot be set in stone; figures from the Stocktake survey suggest lambs are usually weaned between 12 and 14 weeks of age.

If the grass is growing well and ewes are in good condition, weaning can be delayed without reducing lamb liveweight gain. However, if forage availability is low, lamb growth rates will suffer, as ewes and lambs compete for the same grass, AHDB Beef and Lamb advises.

If lamb growth rates are lower than 200g per day, this should trigger weaning and lambs should be moved onto better quality forage.

If creep feed is being fed, liveweight gain may not decline after eight weeks, so weaning decisions should be based on how long the lambs have until they are finished as well as ewe condition.

High quality grass with lots of green leaf and limited stem and dead matter will be greater than 11.5 MJ of ME compared to less than 8 MJ for grass with high degree of dead matter and stem.

Dry matter intake is calculated at four per cent of bodyweight, for example, a 30kg lamb consuming 1.2 kg DM per day with access to 11.5 MJ forage will be consuming 13.8 MJ per day and should be gaining more than 250g per day, see table 1.

Table 1 Energy requirements for growing castrated lambs on forage and the impact of energy intake on growth rates.

Before Weaning

Research has shown that animals which experience novel feeds, such as red clover, chicory or cereals, when with their mothers, perform better once they are exposed to the feed when weaned.

AHDB Beef and Lamb scientist Dr Liz Genever says it can take up to three weeks for the rumen to adapt to a new feed.

"Therefore it’s really important to think about a transition period if the lambs are being weaned onto different feeds," she advises. 

"Any treatments, such as vaccines or wormers, should be given before weaning because stress can affect the immune response, especially to vaccines, making lambs more susceptible to disease."

Ideally, lambs should be weaned onto a pasture they know, but out of sight and sound of the ewes. Once they’ve settled, they can be moved to pasture with a known low worm burden or onto a forage crop. The parasite challenge in recently weaned lambs should be checked with faecal egg counts.

After Weaning

Ewes should be dried off after weaning by providing access to low quality grazing or feed for around two weeks.

"They should then be allocated into groups based on body condition score (BCS)," adds Dr Genever. "Ewes that are above target should be allocated to the poorest grazing and used to tidy up pasture.

Ewes that are below target should be allocated good grazing, as it takes six to eight weeks for a ewe to gain one BCS on unrestricted grazing.

Photo:  Shutterstock

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