Most lambs fed on milk replacer withdrawn from the market because of excessive vitamin-A levels have had to be put down on welfare grounds, according to vets.
Replacer produced by Frank Wright Trouw Nutrition was recalled from 27 distributors in April this year after batches were found to contain 30 times the recommended level of vitamin A. Toxicity was shown to cause sweating, dermatitis and abnormally stiff gait.
Initially it was thought lambs would recover after being moved onto normal milk replacer, but findings suggest irreversible damage had already been done.
Jo Payne, head of toxicology and chemical food safety at the AHVLA, had not been aware of any lambs exposed to the abnormal milk replacer that have not been put down.
“In all the cases I have seen, there appears to be residual affects from excessive vitamin A.
“It appears all initial cases that showed signs of acute toxicity, such as skin changes and sweating, moved on to show chronic signs including reduced growth rates and bone deformities.”
Dr Payne explained that most normal milk replacer would still contain a level of vitamin A at about 50,000 international units. This fed after build up of excessive vitamin-A levels would keep topping up the problem.
Vet John Macfarlane, Alnorthumbria Vets, said he had put down lambs on 15 farms as a result of vitamin-A toxicity.
“One farm had about 100 lambs affected – it was like foot-and-mouth disease all over again.”
He said lambs had appeared to initially recover after being moved off the affected milk powder, but weaning appeared to have caused the symptoms to reappear.
“We now realise that those lambs fed on the abnormal milk replacer are unlikely to ever recover. On my affected clients’ farms, as soon as lambs were weaned they started to show signs of lameness to the point they were lying down.
“This could be due to the fact the lambs were consuming more creep feed, which contains extra vitamin A,” he said.
Normal concentrate will contain enough vitamin A in one kilo of feed to supply 30 lambs. Such levels are fine for normal lambs, but not when fed to lambs with existing liver vitamin-A toxicity.
Post-mortem results showed limb pain was linked to damaged growth plates rather than problems with the joints themselves. Lambs that had done moderately well after moving off the incorrect milk replacer also started to show reduced growth rates.
John Allen, technical director for Trouw Nutrition, said the company was aware the milk powder had caused bone deformities and reduced growth rates in some cases, and in these circumstances it was right to put the animals down.
“A lot of farms affected by the withdrawn milk powder have submitted compensation claims and many have already been visited by loss adjusters. It will depend on individual claims as to the amount awarded, but all factors, such as reduced growth rates, will be considered – we want the situation sorted out as quickly as possible,” he said.