Lambs Went Back On Pure Ryegrass

Press, Volume C, Issue 29518, 20 May 1961, Page 7

Lambs Went Back On Pure Ryegrass

Given nothing but pure ryegrass to eat over the sum-

mer months, lambs in a trial laid down at Springston this last season had shown poor thrift, sickened and died, Mr G. G. Thomson, senior lecturer in veterinary science at Canterbury Agricultural College, told farmers during an inspection of the experimental farm at the college this week.

Mr Thomson described how lambs in October had been taken from Ashley Dene and put on to single species pasture plots. These were of perennial ryegrass, short rotation ryegrass, white clover, lucerne and timothy. In the first phase of about 10 weeks, all the lambs did well and gained 5 to 61b a week, and about half the lambs were drafted off fat at the end of November.

In the second phase of the trial the remaining lambs made only a slight gain over December and began to decline in January with the most severe decline in those grazed on the ryegrass plots. Seventeen lambs died on the perennial ryegrass and seven on the short rotation. Those that did not die scoured badly. Those on the white clover and lucerne and timothy plots continued to make slight gains. The lambs that died were examined, and although most of the® were heavily infested with parasites and suffered from a wide range of conditions there was no single factor which had apparently caused their deaths. Mr Thomson said. ' In the third phase of the trial half of the plots were spelled and shorn lambs from Ashley Dene which had been vaccinated and treated for parasites were put on for 40 days. These lambs all gained about 71b on the ryegrass pastures and those on the white clover—“which they ate with relish”—gained 151 b. The runts from the second phase of the trial were divided into two groups, one of which was drenched, and put on to mature pasture. They all gained in weight.

Some of these lambs were put into the yards and given half a maintenance ration which “dragged off about 201 b bodyweight but caused no ill thrift." Mr Thomson said that it was hoped to carry the trial on for about three years. The plots had all been freshly sown and there had been no sheep on them before the lambs. Stocking had been an initial 20 to the acre in the spring and down to about 16 in the summer.

“We can’t say ryegrass is no good—these are just observations we have made.” he said. “Over the first 10 weeks to the end of November they did exceptionally well but the ones that remained on the ryegrass went back.”