Making Sheep Grow Faster

Press, Volume CIII, Issue 30390, 14 March 1964, Page 7

Making Sheep Grow Faster

'pHE essence of findings at Lincoln College about the relationship between herbage quality and the rate of growth of animals was that where they consumed high quality feed they were able to utilise it more rapidly and they were able to eat more, and this governed the rate of growth. This was stated by Dr. J. W. McLean, head of the veterinary department of the college, speaking to Mackenzie runholders at a field day at Lake Tekapo this week. This season he said that lambs had been weaned at not more than seven weeks and down to five weeks of age and put on respectively white clover, timothy, lucerne, short rotation ryegrass and perennial. They were out of Border Leicester Corriedale cross ewes by Dorset Down rams.

Here Dr. McLean interposed that while traditionally farmers liked to be pure breeders, he would like to suggest that this was precisely the ■ kind of thing that a great many down-country farmers would be doing in the near future and it was not impossible that it could also apply to some high-country ■men too that was advantage of the productivity of crossbred sheep. This season these lambs had grown at up to 0.71 b a day so that in the nine weeks they had been on this trial they had pult on close to 501 b liveweight. These lambs were close to 901 b or a bit more liveweight and some were more than 1001 b at 16 weeks of age. Dr. McLean said that they had had Corriedale' lambs

with an average livewight of 1411 b at the middle of June. “If your hoggets had similar weights you would think that pretty good," he This gave an idea of what the growth potential of these animals was on good quality feed, and in this case at the top of the scale for quality was white clover and at the other end perennial ryegrass. Close to white clover for quality was lucerne, then timothy and short rotation and finally perennial. Dr. McLean saia that where the sheep was on good quality feed the rumen volume was quite low because there was a quick turn-round of feed eaten—it was utilised quickly and the animal was then able to eat more. Where the animal was on poor feed its paunch would be full, indicating that it could not handle it quickly because of its composition in terms of fibre and lack of soluble sugars or nitrogen. The animal did not directly use the protein in its feed. It was broken down by bacteria in the rumen into ammonia and this source of nitrogen was used by the bacteria to manufacture their own protein and this bacterial protein became the major source of protein to the animal. Associated with consumption of high quality feed and high rate of passage through the animal and high intake was a low level of acetic acid and a hgh level of propionic and butyric acids in the rumen and high papillation or wrinkling of the rumen walls. The degree of papillation of the rumen walls could be altered perceptibly in less than three weeks by the quality of feed consumed, he said.