Farm advice: How to deal with ill thrift in lambs

“Lambs begin to graze at three to four weeks of age and will pick up larvae from the pasture,” Mrs Tomlinson says.

“Carrying out a faecal egg count (FEC) at approximately six weeks of age, depending on the weather and time of lambing will help identify a worm burden and the most appropriate timing of treatments.

“Nematodirus risk is often high at the time of first worming and the use of a white wormer is recommended. As there is recognised resistance all over the country to the white wormer group except in nematodiris, I would advise doing a drench check.

“This is done by carrying out another FEC 14 days after treatment. If there is a reduction in eggs of more than 95 per cent, this shows there is no resistance.”

Farmers should not turn out weaned lambs on pasture grazed by ewes and lambs in the same year to reduce the larval challenge, Mrs Tomlinson says.

Worming ewes at lambing will decrease the pasture contamination of eggs from the ewes during the periparturient egg rise.

Mrs Tomlinson corrects the common misconception that tapeworm are responsible for reduced liveweight gain.

The tapeworms seen in faeces will have no detrimental effect on lamb growth rate and are not a cause of ill thrift.

Another potential problem is coccidiosis, a parasite inhabiting the gut wall which usually occurs in lambs at between four and 12 weeks of age. Although it can lead to sudden death it often simply leads to underperformance in young lambs

“A few lambs may appear ‘stale’ and the coat will be dull and if this is the case, it is likely most lambs in the flock will have some level of coccidiosis infection. Four to twelve week old lambs are at risk but the knock-on effects can last longer, as the parasite damages the gut, affecting the absorption of nutrients.

“The problem will worsen through the season with later born lambs more at risk while older lambs over 12 weeks usually develop good age-related immunity. Your vet will provide a diagnosis and suggest the best treatment option, either drenches or in feed medication,” Mrs Tomlinson explains.

Fluke is an increasingly widespread problem and is now found across more of the UK and the host, the mud snail, is active for longer periods during the year as a result of damp summers and mild winters.

“Ewes should be treated with a flukicide in spring as well as autumn to lessen the fluke burden on pasture and reduce the risk of lambs becoming infected”, Mrs Tomlinson says.

Lameness is often ignored as a reason for poor performance in lambs, but its significance should not be underestimated, according to Mrs Tomlinson.

“Lameness in lambs is usually scald, caused by irritation from long wet grass or rough grazing containing thistles allowing dual infection from the bacteria dichelobacter nodosus and fusobacterium necrophorum,” she says.

“It is vital to treat mild lameness as soon as it is evident to prevent it from becoming more serious or developing into foot rot. Preventing lameness in ewes will help to protect lambs, as it reduces the burden of infection.”

“Where there has been a scald or foot rot problem in the flock, leaving pasture clear of ewes for a minimum of a month before grazing with lambs will reduce the risk of re-infection,” Mrs Tomlinson adds.

Even when all the correct preventative measures are taken, problems will still arise in the
lamb crop leading to poor growth rates or disease. Isolating the underlying reason for illness or poor performance is vital for welfare and economic reasons.

“At Westpoint Farm Vets, we are teaching our farmers how to carry out simple on farm post-mortem, as these may give an indication as to the cause of death,” she adds.

“If there is no obvious cause and more deaths are occurring, it is worth investing in a detailed post-mortem carried out by your vet.”