HIGH COUNTRY SHEEP PROBLEM

Press, Volume CIII, Issue 30390, 14 March 1964, Page 6

HIGH COUNTRY SHEEP PROBLEM

A belief that a high standard of hygiene in the shearing shed and associated yards was not the only factor involved in limiting the spread of the disease known as lympho in high country sheep was expressed by Dr. G. K. Cordell, veterinary advisory officer (sheep diseases) of the Department of Agriculture, Christchurch, speaking to Mackenzie Country runholders at Lake Tekapo this week. Dr. Cordell said that he was convinced that there was such a thing as lineage resistance to the disease, and he also put forward a personal theory that the itch mite, which spends part of its life just under the skin of the sheep, might, if it penetrated to the lymphatic drainage system, transport the bacteria responsible for the disease to the superficial lymph glands where the disease was usually seen. The disease, caused by a bacteria which enters the animal when, for instance, it is cut at shearing, usually infects one of four superficial lymph glands. Where an abscess caused by the disease is exposed the bacteria is exuded and any surface contaminated with this material is a potential source of further infection.

Discussing a five-year study of the disease now under way in the South Island high country. Dr. Cordell said it had been found that about 20 stations were concerned at the incidence of the disease as represented in rejection of carcases for export. Last year he said that 2.6 per cent of carcases (other than lambs) had been rejected in the South Island for this reason and 0.1 per cent of lambs. Involving the rejection of 11,000 lambs and 60.000 sheep this was a considerable loss of overseas income.

On six stations, sheep aged one year, two years, three years and four years and over had been felt or palpated at the four points mentioned to determine the presence of i

infected glands. Palpations while the sheep were in the wool and then immediately after shearing when the procedure was easier, had indicated that about 20 per cent had been missed in the wool, he said. , Another check made a month later was designed to determine whether there was an increase in the disease due to shearing cuts and thus whether shed and yard hygiene was a vital factor. One property, where Dr. Cordell said there had been a lympho incidence of 20 to 30 per cent 10 years ago it had almost been completely done away with following the adoption of improved shed hygiene. Methods In this shed the floor and walls were constructed of 7ft by 4ft sheets of 13/16th of an inch combination hardboard and coreboard. The painted shearing board was washed down every night. Shearers on the property used blades and their water pots were cleaned out every morning and filled with a disinfectant. These pots were tipped out on to the floor at night wash-up and more disinfectant added. This was left to soak for about two or three minutes, scrubbed down, and then gone over with a rubber “squeegie.” The counting-out pens were hosed down every night. They had concrete floors and sides and no roofs. The sheep went straight out on to a 200acre block after counting-out and were never held in the yards. After two days on the block they were remustered and brought in and dipped. Should it be dusty in the dipping yards they were hosed down, as was also the race entering the shed, when dusty conditions prevailed.

Dr. Cordell recalled that in the North Island tests had been carried out using 6000 sheep to determine the suitability of various flooring materials for sheds designed to reduce the incidence of lympho. First-grade lino had been the first choice as a

tough, maintenance-free floori material for an ultrahygienic shearing floor. It was recommended that it be joined between the portholes of the shed and that stainless steel be used for finishing at the entrance of the porthole. But Dr. Cordell said that he did not think th'at hygiene was the whole story about lympho. One property under study had a high incidence of the disease while another station which used the same shed with the same shearers had no disease. This was a dramatic case pointing to a lineage resistance and the Australians were working on this approach to the problem. Alluding to the possible role of the itch mite, Dr. Cordell said he felt that there might also be evidence pointing to other ways of transmitting the disease, such as external parasites. Dr. Cordell said that to check on the accuracy of physical palpations of the superficial lymph nodes, 550 Merino wethers and 50 ewes aged five years and over had been handled. Eightly of these had been culled for the disease and of the remainder 515 had been sent to the works as free from the trouble, but 115 had subsequently been rejected for the disease.

These palpations had been done by a technician who was as expert as anyone and it indicated that culling on physical palpation could not be fully relied on. At the same time the high level of the disease, indicating that the incidence was far greater than had been demonstrated by the physical palpation, did underline the need for urgency in the control and eradication of the disease.

Dr. Cordell said it seemed from their work at this stage that the two-year-old group were most susceptible to the disease, and because of the incidence of the disease in older sheep it was wise for younger sheep to be shorn first in the shearing round. The help of an oil and chemical company was being received in the investigation of a non-corrosive, non-stain-ing and antiseptic machine shearing lubricant.