Reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels

ABSTRACT

The objective of this study was to evaluate the reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels. Ewes were assessed for weight and body condition at the beginning and end of flushing periods. Lambing rates and rates of proliferation were also evaluated. Crossbred woolly ewes (n = 46), 36 ± 2 months of age and rated 3.0 ± 0.1 on a body condition scale that spanned from 1 to 5 were divided into four treatment groups. One group received no feed supplements (NFS), while the others were supplemented for 64 days 21 days before and 43 days during the mating season. The latter groups were fed soybean hulls at 0.6% (S06), 0.9% (S09) and 1.2% (S12) of their body weight (BW), calculated using dry mass. Ewes were mated for 50 days with four rams by means of natural breeding in October and November, which is spring in Brazil. There was no significant difference among the treatments based on mean BW of the ewes before and after the supplementation period (P > 0.05). Similarly, no differences were found in the rates of proliferation (P > 0.05). The S09 treatment presented the highest lambing rate (82%, 9/11), while the NFS treatment correlated with the lowest rate (42%, 5/12; P < 0.05). There was a positive linear effect for body condition score as the supplementation level increased (P < 0.05). We conclude that a supplementation level of 0.9% BW seems to improve lambing rates for ewes that undergo springtime mating.