How to keep lamb infections minimal
INFECTIOUS diseases in young lambs represent 10% to 15% of total losses, according to Chris Lewis, from the Veterinary Investigation Centre at Crewe, Cheshire.
But quality feeding – which, in turn, means quality colostrum – adequate shelter, quality shepherding and correct stocking rates can help minimise disease outbreaks.
Speaking at a seminar on lamb welfare, Dr Lewis said that accurate diagnosis of the cause of scouring could only be ascertained on lab examination of a faeces sample, not through a swab. The result might show that either E coli, salmonella, rotavirus, coccidiosis, pulpy kidney or lamb dysentery is responsible.
The latter two inevitably resulted in death once symptoms were obvious. "Frequently lambs exhibit a degree of central nervous disturbance in the hour or so before death," said Dr Lewis. "There is no excuse for these diseases to be seen in any sheep in this country, since efficient clostridial vaccines are available. The provision of correct vaccination techniques and adequate colostrum ought to consign these diseases to history."
E coli and salmonella could be controlled through antibiotics, as well as, where appropriate, by fluids. "Coccidiosis is untreatable as such. Control of secondary bacterial infection by antibiotics and the restoration of fluid balance is important. It is best controlled by good management techniques and a good supply of colostrum, as well as adequate bedding," said Dr Lewis, who handed out the same advice for controlling rotavirus.
Long-term prevention of E coli and salmonella was through specific vaccines, ensuring maternal antibodies were transferred via colostrum. In the case of lamb dysentery and pulpy kidney, correct vaccination and boosters were essential. "This involves a full primary course of two doses six to eight weeks apart, followed by an annual booster given no later then four weeks before lambing," advised Dr Lewis.
"Coccidiosis can be reduced by hygiene. The use of the approved disinfectant Oocide helps reduce environmental contamination. And try not to use buildings which have housed calves previously," he said.
rotavirus is often sporadic and unrelated to those strains which affect cattle, but generally ewes which have met the disease one year will produce sufficient antibody in their colostrum and milk the following year to prevent disease in their lambs."
Dr Lewis concluded by pointing out that although good hygiene is an important factor in controlling salmonella, rodent control – especially mice – is also important. "Mice are frequently unaffected by salmonella, but they excrete large numbers of bacteria and have the ability to defecate 100 times a day. This allows for a very efficient distribution of salmonella – particularly on foodstuffs," he said.
Ways to counter their effect
• Feed quality colostrum.
• Use correct vaccination technique.
• Ensure adequate hygiene at lambing.