Grouping dairy ewes by nutritional requirements for winter feeding

Abstract

In large flocks of dairy ewes, classical concepts of animal feeding can no longer be applied because of the increasing variability of performances. Simplified feeding practices by means of generalised group-feeding rarely impair animal health and apparent productivity because many physiological regulations permit each animal to adapt to imperfect nutrient supply (either excess or deficit). However, in these conditions, predictions of ewe’s performances are almost impossible since animal responses to such a variation in nutrient balance is mostly unknown. In this paper, main production factors accounting for the variability of requirements are described and their usefulness is discussed with respect to the efficiency of allocation criteria into smaller sized group-feeding. In a trial, two identical small flocks of 96 ewes were either conducted together (Mixed) or separated in two groups according to milk yield (Separated-High n=48 and Separated-Low n=48). Within each group the feeding objective was to supply concentrates in order to satisfy 85 % of the ewes, with forages available ad libitum. After 100 days, for each of the two treatments (Mixed vs Separated), mean consumptions were very close and mean milk yield were non significantly different (resp. 171 vs 175 l/100d). Concentrate distribution could have been decreased in Separated-Low group to earn concentrate. That’s what was done in an on farm trial without control of forage intake. Comparison was made between a group (n=67 ewes) receiving classical amounts of concentrate (Classical) while the other group was divided in four sub-groups receiving adjusted amounts of concentrates according to their milk yield by means of an electronic feeder. On the whole experimental period, mean milk yield were the same (Classical 284.6 l/180d vs Adjusted 282.2 l/180d), with a difference of 51 kg concentrate less per ewe for adjusted treatments. The future of such techniques, in order to increase nutrient efficiency and performance of dairy ewes, will depend on the development of electronic recognition devices (individual feeding, electronic gates) and automated measurements (milk control, body weight).