STUDY OF EWE FEEDING AFTER MATING

Press, Volume CVII, Issue 31542, 2 December 1967, Page 10

STUDY OF EWE FEEDING AFTER MATING

On the basis of studies made with ewes at Ashley Dene the practice of restricting the intake of ewes after mating and conserving feed for the period immediately before lambing and after lambing is sound. In other words there is no significant effect on lambing percentage and the proportion of barren ewes.

Professor I. E. Coop, professor of animal science at the college, said recently that during the four-year period from 1962 to 1965 the large numbers of ewes available on the college’s Ashley Dene property had been used to study the influence of liveweight at mating and of flushing on lambing percentage, and in particular on the percentage of ewes bearing twins and those that were barren. These studies had shown that the higher the liveweight of ewes at mating the more twins there were born and the fewer barren ewes there were, and that flushing also increased the percentage of twin-bearing ewes but did not decrease the percentage of barren ewes.

During the last two years Professor Coop said that attention had been directed to the influence of nutrition immediately after mating. The significance of this was that it was believed that the level of nutrition after mating was not critical as was the case immediately before lambing and during lambing, and therefore the practice had grown up of restricting the level of feeding after mating in order to conserve feed needed in the more critical July and August period. The practice had been widely advocated and had much to commend it as it allowed high quality autumn saved pasture and winter saved grass to be held through to July and August. But the effects of this restricted feeding after mating in terms of lambing percentage had not been demonstrated. This restricted feeding might well occur at a

time when the egg was Implanting in the uterus and, in the early development stages when embryonic loss was possible.

Using the large number of readily available ewes at Ashley Dene a trial had been started last year in which a mob of 450 ewes had been run on a maintenance diet after mating, while another group of 450 ewes had been put on a restricted diet for five weeks from April 15 to May 26. At the start of this period the ewes would have been two to three weeks pregnant and the rams were still running with both groups. In this period the restricted mob lost 91b of bodyweight as compared with the ewes on maintenance.

At lambing the low plane group,had a lambing percentage to ewes lambing of 145 per cent, compared with 141 for the other group, and there were also slightly fewer dry ewes in the restricted diet group.

In the last year the trial had been repeated. On this occasion two groups each of 250 early-lambing Border Letcester-Corriedales that were about six to eight weeks pregnant had also been subjected to the differential feeding routine. Groups also of 500 ewes two to three weeks pregnant had also been used, with the period of differential feeding being from April 14 to May 29. In this period there had been an 111 b body weight loss in the restricted group and a 11b loss in the other group.

Among tfhe early-lambing ewes that had been six to eight weeks pregnant at the start of the study there was basically no difference between the two treatments with the lambing percentages to ewes lambing being 155 per cent in both cases. There had, however, been slightly fewer barren ewes in the restricted group. In the case of the main mob ewes two to three weeks pregnant at the start, the lambing percentage, again to ewes lambing, had been 146 for the higher plane group and 142 in the restricted. Here there was no difference in the proportion of barren ewes.

It could be seen from these results that the differences were relatively small and not

consistent This suggested that no barm would accrue from the practice of restricted feeding after mating where the length of restriction was about five or six weeks and the body weight loss was about 101 b. Questioned about the effect of a larger loss of, say, about 201 b, Professor Coop said he would not guess what would happen. He commented that some work had been done in Australia where a restricted nutrition had been continued to almost lambing, and here it did show a deleterious effect, so the possibility existed if the practice was carried to an extreme that there could be some embryonic loss. One other thing that had come out of the experiment was that there did seem to be a short period of a few days when the twinning in the restricted group was significantly lower than in the unrestricted. It was considered that there was a critical period relative to the date of implantation when restricted feeding could effect embryonic survival and this should probably be looked at more carefully, but nevertheless it could be seen that even fairly severe restriction of feed for several weeks at the end of mating did not appear to have any very significant deleterious effect.