A note on the influence of the pattern of live-weight and body condition recovery between weaning and mating on food consumption and reproductive performance of Scottish Blackface ewes

Extract

Previous studies on the Scottish Blackface breed have shown that ovulation rate and lambing performance are closely related to body condition at mating. Ovulation rates greater than two were achieved from ewes in good body condition (grade 3·0 on a scoring system described by Russel, Doney & Gunn, 1969) and this performance was not affected by condition either rising or falling to the pre-determined grade at mating (Gunn, Doney & Russel, 1969). Ewes in lower body condition at mating (described by grades 1·5, 2·0 and 2·5) were found to have correspondingly lower mean ovulation rates (Gunn et al. 1969; R. G. Gunn and J. M. Doney, unpublished). In these, and other experiments giving similar results, the experimentally controlled changes in nutrition and hence body condition were imposed for only a few weeks prior to mating, i.e. during late October and November. However, in traditional hill grazing systems, ewe recovery may be expected earlier and may be followed by a considerably longer period of live-weight and condition maintenance. In situations where some degree of grazing control can be used to modify the nutrient intake cycle, it is important to know if food consumption and subsequent reproductive performance can be influenced by the long-term pattern of recovery.