Pickings, problems for sheep on the Plains

Press, 11 March 1983, Page 20

Pickings, problems for sheep on the Plains

LIVESTOCK MONITOR

Several outbreaks of illness and death in lambs and ewes due to a bacterial gut infection and kidney damage (nephritis) have been reported in Canterbury. Eight cases of this "winter scour” had been reported by early this week in Darfield and Waimate areas. The Lincoln animal health laboratory of the Ministry of Agriculture and Fisheries is investigating the problem. Mr Brian Cox,' a veterinary investigation officer at the laboratory, said that up to 30 per cent of the sheep in a flock were affected and 3 to 4 per cent of these died. “It isn’t a major problem at the moment but we are working on finding the cause,” he said. Severe enteritis and diarrohea are the most obvious symptoms, with depression and malaise. One symptom that is puzzling scientists at the laboratory is nephritis (kidney damage). “We have isolated a bacterium from the affected lambs, but we are not sure if it is the one causing the problem," said Mr Cox. "This bacterium has not been credited with causing kidney damage in the past. “If it is the cause there may be some triggering factor such as stress. We are looking at any common factors in the outbreaks to see if we can trace this trigger." All sheep faeces sent to the laboratry were being cultured to see if the bacterium was a common one, and veterinarians in the region had been asked to look out for the problem. “At present we can't advise any particular treatment until we can work out what is causing the problem. The best thing to do would be to spread out the affected sheep and reduce stress as much as possible,” said Mr Cox. In spite of the continuing drought in North Canterbury

some farmers are managing to keep ewe liveweights up for tupping. The average weight of the ewes in the Darfield flock used for the monthly livestock monitor was 53.5 kg when they were weighed recently, an increase of 4kg since the beginning of February. Although there had been no pasture growth and paddocks were down to bare earth in places, the ewes had been grazing on stubble left after harvesting, said Mr Stuart White, a field officer with the Ministry of Agriculture and Fisheries at Darfield. Because the ewes were in good condition, consideration was being given to putting them to the ram a little earlier than usual, in case the food supply ran out and they lost weight. “This may cause a few problems with early lambing, but it will probably be only about 10 days earlier so the risk is not too great.” said Mr White. The monitor hogget flock has not fared so well and their average liveweight had remained static at 42kg. The hoggets have been feeding on dry pastures and meadow 'hay and have done well to hold their condition. “The hoggets won’t be put to the ram until April 5," said Mr White. “They will be fed rape and grain before then to improve their growth rate, but it will be difficult." There had been some cases of hairy shaker disease in lambs, according to Mi- Bob Gumbrell, of the Lincoln animal health laboratory. The

symptoms of hairy shaker were hairy lambs and shaking Because there was no treatment for this disease, farmers should take preventative measures. When buying in ewes they should be run with other ewes already on the farm for as long as possible before putting them to the ram. This would ensure that all the ewes were infected with the disease. The ewes would not be affected and this immunity would be passed to their offspring. The ewes must be infected by the disease before conception 'for the immunity to be passed on. Farmers should also be vaccinating sheep against Campylobacter abortion (vibriosis). said Mr Gumbrell. Veterinarians would be able to offer advice on the use of this vaccine. Other steps in animal health farmers should be taking include inspecting their rams for scrotal mange, pizzle rot and epididymits. The rams should be shorn or crutched. their feet trimmed and vaccinated against footrot if necessary. Mr Alan Pearson, a veterinarian at the Malvern Farmers’ Veterinary Club at Darfield, said grain feeding of sheep was being advocated in some areas to help maintain body weights. In many cases the weights of fourtooth ewes were well down because they had experienced two successive hard seasons and some had raised a lamb as well. Mr Pearson suggested ewes should be drenched or

vaccinated with selenium before taking the ram. Marginal selenium levels could cause a loss of fertilised eggs resulting in a decrease in lambing percentages. As well dogs should be vaccinated against canine parvovirus, a serious disease common in young dogs. The disease caused depression, vomiting, and diarrohea in dogs and was often fatal. The Winchmore Irrigation Research Station of the M.A.F. reports that the rainfall for the month of February in that area was only 15.’3mm. about one-quarter of the monthly mean rainfall. The rainfall was only half that of last February. However temperatures have been significantly below normal (under the influence of the Southern Oscillation - see accompanying story) and this has kept evapotranspiration down. The average air temperature during February was 14.7 degrees, down one degree from the long-term mean for February and 2.5 degrees from the average during February 1982 of 17.3. The highest temperature during the past month, at 28.4. was well below the highest recorded during February, of 38.5, and the highest during February 1982, of 36.3. Soil temperature was also about one degree below normal and the evaporation only about 80 per cent of normal. Soil moisture was the same as February 1982, indicating the difficulties MidCanterbury farmers still face because of drought conditions.