Influence of Nutrition upon Duration of Gestation in Sheep

Abstract

VARIOUS effects of different planes of nutrition on pregnancy in the ewe have been studied; but there appears to be no record of an effect on duration of gestation. Four series¹ of observations were made, in which Merino ewes were maintained on high, medium and low planes of nutrition from the 108th, 129th, 136th or 143rd day of pregnancy to parturition. The distribution of the treatments among the four series is shown in Table 1. Prior to the experimental nutritional period, ewes had either been maintaining or gaining weight. During the experimental period, the ewes on the low plane in series 4 and 6 received chaffed wheaten hay only. All other ewes received a mixture of equal parts of oats and chaffed legume hay, with or without pasture. Ewes on the high plane of nutrition in each instance were allowed access to food ad lib. and gained about 0.2–0.4 kgm. in weight per head per day. In each series the ewes on the low plane of nutrition received about 0.2 kgm. (dry weight) of food per day each and lost about 0.2–0.4 kgm. in weight per day. Ewes on the medium plane received sufficient food to maintain, constant body-weight.