Days of stock thrift problems recalled

Press, 15 May 1981, Page 14

Days of stock thrift problems recalled

Mr G. G. (Graham) Thomson, who retired from the veterinary department at Lincoln College late last year after more than 30 years, was involved in the studies in the 1950 s that eventually led to the demonstration of the importance of selenium in stock health in Canterbury and other parts of the country too.

That, he recalls, was "a major break-through” in animal health knowledge.

He has been a reader since 1968.

Mr Thomson’s first contact with Lincoln was briefly as a student in 1940 after doing his medical intermediate at Otago University in Dunedin, where he was born. That was in war time and soon afterwards he went off to Britain to serve in the Royal Navy. He spent most of his service in corvettes and destroyers in British waters and in 1944 was involved in the landings on the Normandy coast when Allied forces invaded France in the closing stages of World War 11.

Afterwards, under a rehabilitation bursary, he studied from 1945 until 1949 at the Royal (Dick) Veterinary College at Edinburgh, where he took a diploma and at the same time he completed a bachelor of science in veterinary science at the University of Edinburgh. In early 1950 he returned to Lincoln as a lecturer in physiology and animal health in the veterinary department after being engaged by the late Professor E. R. Hudson, when he was on a visit to Britain the previous year. Mr Thomson conducted the clinical practice at the college, which provided a service for outside farmers as well as the college farms, but with the growth of veterinary services and increased numbers of veterinary surgeons working in the rural •community it had almost ceased to exist when Mr Thomson retired late last year. He admits to clinical practice being what he wanted to &o from the time that he first thought about becoming a veterinarian and it is an interest that has persisted ever since. Early in his period at Lincoln he spent some time evaluating the treatment for pregnancy toxaemia and reflects that after about 30 years they are not much further ahead in handling this very complex trouble. But he believes that a team effort involving a number of scientists could well be rewarding in producing a solution. It still remains a serious disease with figures showing some 5 to 10 per cent of sheep being affected depending on season and feed supply. The best approach is still to prevent the trouble in late pregnancy when the lamb is growing ’fastest by. feeding

ewes adequately and if the trouble does show up then use of glycerine or the induction of lambing seem to be the best solutions, but because it comes early in the lambing season Mr Thomson says that farmers tend to soon forget about it. It was not long before Mr Thomson was also involved in a mounting problem in the 1950 s characterised by stock ill-thrift, particularly at the hogget stage, and white muscle disease. He remembers that individually all the minerals in the periodic table were tried singly and in combination to counter the problems, that in some areas saw lambing percentages drop to as low as about 30 per cent.

The one mineral that was not used was selenium and its use, too, was prompted by work in the United States which showed that lack of it could lead to disease in rats.

When it was brought into the investigations in the late 1950 s it was quickly shown that when administered to ewes and young lambs it put a complete stop to white muscle,- and it also resulted in spectacular increases in lamb growth rate. Mr Thomson says that the’ mode by which selenium works is still not well understood, but it seemed that at a time when development programmes involving the introduction of improved pasture species and topdressing were being implemented the increased sulphate levels resulted in the uptake of selenium in plants, already at a low level, being further reduced to dangerously low levels and the animals grazing on these swards consequently became prone to the problems already mentioned.

At this time Mr Thomson remembers that quite a lot of effort was put into investigation of rates of selenium treatment and also methods of administering it to stock, including bullets, which would hopefully obviate the need for regular treatment of animals, but problems arose with the bullets being covered with a coating of calcium salts, which resulted in the selenium not being

available, and because little selenium was passed on from ewes to lambs in the milk and selenium salts were relatively cheap so that two doses could be given for the cost of about lc. the interest in a bullet declined. But he notes that trials are continuing at Ruakura animal research centre into the application of selenium in topdressing and so long as this is not toxic and not too costly it could obviate a lot of work and effort. With Professor J. W. McLean Mr Thomson was also involved in a study of the effects on animal growth of a range of grasses and legumes grown individually and this showed that legumes had been under-estimated as a fattening feed. It was shown that where similar lambs were grazed bn similar areas of ryegrass and legumes the growth achieved on the latter was double that on ryegrass associated with the greater digestibility of the legumes compared with the more fibrous ryegrass. Mr Thomson also worked with Dr C. S. M. Hopkirk on the scheme to clear local town milk supply herds of brucellosis carrying out blood tests on animals shown through milk to have brucellosis. After Professor McLean’s retirement he was involved in the running of courses for meat inspectors, which are now conducted in freezing works by the Ministry of Agriculture, and at the college these courses are now confined to those for senior inspectors. More recently Mr Thomson has been involved in helping in preparing animals for experimental surgery. During his period at the college he served for a period as chairman of the college branch of the Association of University Teachers. Away from the college he served on the committee of the Canterbury Sheltered Workshops and on a school committee. One of his interests has been yachting and he owns a keeler.

One of his daughters, Caroline, took a diploma of agricultural science specialising in entomology at the college after taking a bachelor of science degree at Canterbury. She is now with the Forest Research Institute and working on Stewart Island.

Another daughter, Jane, is a general practitioner in Christchurch and a son, Andrew, is a registrar at Christchurch Public Hospital.

Mr Thomson is not inclined to go along with those who belittle youth. His experience is that individually they are upright, tolerant and able and better educated than young people were in the days of his youth. They are at least the equal of those of the past.