Use of nutritional restriction at mating to dampen reproductive performance of 'FecB'-carrier merino ewes

Abstract

The nutritional milieu strongly influences ovulation rate in both carriers and non-carriers of the Booroola fecundity gene ('FecB') (Montgomery et al. 1983; Kleemann et al. 1991). On the property 'Allandale' both homozygous ('FecB^BB') and heterozygous ('FecB^B+') merino ewes have large litter sizes (LSs) (2.1 and 2.3 respectively) and excessive losses from ovulation to weaning (>64%) (Walkden-Brown et al. 2007). This study reports an attempt to inhibit the expression of 'FecB' by a period of nutritional restriction, resulting in weight loss at mating.