Why blood testing in-lamb ewes can prevent health problems

Taking metabolic profiles of in-lamb ewes three weeks before lambing can make a massive difference to colostrum and milk production by rectifying dietary shortfalls in energy and protein, say vets.

At a cost of about £90 for a flock profile based on samples taken from about 20 ewes, it is something that Northumberland vet Joe Henry says is now becoming a routine pre-lambing procedure for many flocks.

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“In-lamb ewes may appear to be doing fine, suggesting their diet is providing all their nutritional requirements, but even though there may be no tell-tale clinical signs, shortfalls in energy and protein will have a serious impact after lambing,” says Mr Henry of Alnorthumbria Vet Group.

“Insufficient and poor-quality colostrum, depressed milk production and an increased risk of twin-lamb disease are problems that can be avoided when dietary deficiencies are tackled in late pregnancy.

“And even within the final three weeks before lambing there’s time to do that. It’s about tweaking the diet to correct issues that you can’t actually see but when addressed will optimise ewe performance,” he adds.

Early warning system

Vets say metabolic profiling provides a valuable “early warning system” and is the only effective way of checking that a diet is meeting a ewe’s needs.

“While the diet may appear to be providing all a ewe requires – and she may not be showing any clinical signs that would indicate any nutritional issues – the metabolic profile will tell the real story.”

It’s recommended blood samples are taken from ewes from various groups within the flock – twin-bearing, triplet-bearing and probably gimmers carrying twins – to make up the 20 “across flock” blood samples.

“We’ve seen disastrous problems in the past caused by watery mouth or joint ill, where there have been big lamb losses because ewes just didn’t have enough colostrum.

Lambs are sucking but there’s not enough for them and what they do get doesn’t give then them the antibodies they need.

“Ewes that have been short of protein in late pregnancy won’t show any clinical signs but once they start lambing the problems start.

A flock can be well into lambing before it’s realised that the colostrum isn’t doing its job – but then it’s too late,” says Mr Henry.

Simple tweak to diet

Results from the metabolic profile may show that just a simple “tweak” of the ration – say increasing from an 18% protein concentrate to a 20% protein level – is all that’s needed.

“But if that change is missed there are likely to be problems after lambing that could have been avoided. Where flocks have changed any of their management practices in the way in-lamb ewes are fed or housed, it can often trigger nutritional problems.

“We know that two-thirds of all ewes that go down with twin-lamb disease end up dying. It’s horrendous,” says Mr Henry.

Metabolic profiling of the 1,500 Mule ewe flock run at Hedgeley Farms, Alnwick, Northumberland, has been under way for the past 10 years.

Assistant manager Vicky Hogg says they do it for peace of mind more than anything else and she says it’s well worth the cost.

“We start lambing on 1 April and house about 800 ewes after scanning in mid-January. We feed a TMR mix to the housed ewes and take blood samples in early March to make sure everything is running fine,” she says.