7 tips for weaning and post-weaning management of lambs

When to wean is one of the most important decisions in a flock’s calendar, influencing lamb performance and ewe scanning rates.

Charlotte Mouland from Synergy Farm Health says the weaning date will be different each year depending on several factors.

There should be no fixed date in the diary. It should be based on ewe condition, lamb growth rates and grass availability, she says.

See also: Benefits of breeding values in lamb weights and ewe fertility

“This year might look very different to last year [when] there was a drought. In the South West, we have had plenty of rain over the past few weeks and ewe condition is much improved.”

Charlotte shares advice on weaning and post-weaning management to maximise lamb performance.

1. Use eight-week weight data

Eight-week weights are a good starting point to assess how lambs are growing.

As a rule of thumb, if they are not achieving 200g/day by 10-12 weeks, lambs should be weaned earlier.

From eight weeks, ewes and lambs will start competing for grass.

Ideally, lambs should be weaned onto pasture they know and that is out of sight of ewes, to reduce stress.

“Remember, it can take three to four weeks for the rumen to adjust to a diet change, so stage the transition,” Charlotte says.

2. Group lambs according to weight

She advises splitting weaned lambs from commercial lowland flocks into three batches, based on weight:

• Long-term keep (less than 30kg)
• Medium-term (30-35kg)
• Short-term (more than 35kg).

Growing lambs can eat 4% of their bodyweight in dry matter daily.

Once in their groups, feeding plans can be accurately developed alongside forage budgets.

Graze pasture at the correct height, so lambs are eating the highest-quality grass and not working too hard.

In set-stocking scenarios, this should be 6-8cm, or 10-12cm if lambs are rotationally grazing.

Lambs should be removed once grass residuals hit 5-7cm.

Last year, drought limited feed availability, while recent rain this season has replenished grass, says Charlotte.

“Last year was a real headache for farmers. Conversely, if we continue to get unsettled weather, it will be a challenge for lameness and worms instead.”

With improved grass growth, there may be less need to finish lambs earlier to relieve grazing pressure.

However, strong lamb prices might still make concentrate feeding an attractive option, especially for smaller lambs.

“The lamb price hasn’t dipped below £6/kg for the past two years, which does open conversations around feeding concentrates.

“The feed conversion efficiency is much better in young lambs, so it’s better to do it earlier in the season,” she advises.

3. Graze to manage parasites

Once weaned, lambs should be returned to the same field they came from for a few days, to reduce stress. They can then be moved to clean grazing to help manage parasites.

Clean grazing is pasture that has not had ewes or lambs on it in the current season, such as silage aftermaths or a new reseed.

If no clean grazing is available, the next best option is a field that has been grazed by cattle or adult ewes, because they act as a “vacuum” for worms.

However, Haemonchus contortus remains a threat (see tip 4), because ewes do not tend to develop age immunity to the gastrointestinal roundworm.

Flocks in parts of the country that have recently experienced warm, wet weather will likely see this followed by higher strongyle expression. Haemonchus also favours these conditions.

Charlotte advises keeping a close watch for parasites by conducting faecal egg counts every three to four weeks.

These can be interpreted with the farm vet, along with lamb growth data, to determine whether treatment is necessary.

“Weigh every four weeks to estimate days to finish and evaluate lamb performance.

“This will also help check that management changes to diet or worm treatments have had the desired effect.”

A mid-season “knock-out” drench, using the newer orange and purple wormers, should be administered in the later part of the grazing season.

This will remove any worms that may have survived previous treatments with white, yellow and clear products. It also helps prevent resistance developing.

4. Watch out for haemonchus

Haemonchus, otherwise known as barber’s pole worm, can often catch farmers out because it does not present as a typical worm infestation, warns Charlotte.

“Lambs can be lethargic and lag behind. They might not scour, but the inside of their eyelid is pale.

“This is caused by the roundworm sucking blood in the abomasum.”

One adult female can lay 5,000 eggs/day, and sheep can rapidly become very anaemic.

Peanut agglutinin tests can be used to diagnose haemonchus, with the fluorescent stain binding only to haemonchus eggs. 

Narrow-spectrum worming products such as Closantel can be used to treat haemonchus to reduce pressure on broad-spectrum ones.

However, the parasite can develop drug resistance rapidly, so treatments must be discussed with the vet.

A Famacha scorecard can be used to assess the colour of the inner lower eyelids, allowing targeted treatment.

5. Test for trace elements

Deficiencies in trace elements, particularly cobalt, copper, selenium and iodine, may present once lambs are completely reliant on forage.

Poor growth rates may be the first symptom, alongside poor fleece quality and high worm burdens.

Blood samples should be taken in conjunction with the vet to test for any deficiencies.

Lambs can be supplemented with mineralised concentrate, boluses or drenches.

6. Be aware of pneumonic pasteurella

Changeable weather can lead to a spike in pasteurellosis cases, as has happened recently in the South West, warns Charlotte.

“It has been hot and cold, wet and dry. Seek veterinary advice and try to minimise handling during an outbreak, as it can perpetuate losses.”

Active protection from vaccination lasts eight weeks, so a booster may be required before the autumn when pasteurella cases are typically seen, she advises.

7. Tweak management for entire rams

Charlotte says more flocks are leaving ram lambs entire, a trend she predicts will grow because of proposed changes to legislation (new methods of tailing and castration, set requirements for pain relief during procedures and restrictions on who can perform them).

The Defra consultation closed in March, and a response is expected later this autumn.

“Rams can achieve higher growth rates driven by testosterone.

“But they need to be managed carefully and must be separated from females by five months of age at the very latest and earlier for early-maturing breeds,” she warns.

Rams should be kept out of the sight and sound of females to avoid pacing and fighting.

Farmers also need to be aware that rams will handle differently when they are selecting animals for slaughter.

“Rams tend to be leaner but with better confirmation, as testosterone drives muscle growth,” she advises.