Molasses-based supplement improved the metabolic status of late-pregnant ewes bearing multiple fetuses

Abstract

Metabolizable energy requirements rise dramatically at late gestation in ewes bearing multiple-fetuses; consequently, prolific ewes may suffer pregnancy toxemia and fetal intrauterine growth restriction. The present objectives of this study were to examine in ewes bearing ≥2 fetuses, the effects of dietary supplementation with a molasses-based product from 90 d of pregnancy until lambing on dams' metabolic status and perinatal lambs' performance. Fifty Afec-Assaf ewes, genetically bred to achieve multiple-fetus pregnancies, and bearing at least 2 fetuses were included in the study. The ewes were divided into two groups according to predicted number of fetuses, lambing time, parity number, and body weight (BW). The control group (CTL) was fed solely a basal diet; the treatment group (MLS) was fed the same diet supplemented with the molasses-based product ENERGILASS Sheep 15, in free-choice tubs. Blood samples were collected weekly. Average litter sizes were 3.06 and 3.19 for CTL and MLS groups, respectively. Fetal survival rates at birth differed insignificantly (P>0.05) at 0.82 and 0.84 in the CTL and MLS group, respectively, and the survival rate of lambs until weaning was insignificantly 6.8% higher in the MLS than in the CTL group (P>0.05). The CTL ewes lost 0.40 body condition score units from 90 d of pregnancy until lambing compared with only 0.15 by the MLS ewes (P<0.05). The average concentration of glucose in plasma during the last 3 wk of pregnancy was 17.3% higher in MLS than in CTL ewes (59.1 vs 50.4mg/dL, respectively; P<0.01), whereas the BHBA concentrations were 30.9% lower (0.67 vs 0.97mmol/L, respectively; P<0.03) and NEFA concentrations were 30.0% lower in the MLS than in the CTL ewes (P<0.007). During the last 3 wk of pregnancy glucose concentrations were ≤50mg/dL in 37/70 and 16/72 of the CTL and MLS blood samples, respectively (P<0.0002). Also, BHBA concentrations ≥1.4mmol/L were found in 19/70 and 6/72, respectively, of the CTL and MLS blood samples (P<0.003). In conclusion, molasses-based product supplementation to prolific ewes from 90 d in pregnancy until lambing greatly improved the metabolic status of dams but with minor effects on perinatal survival and growth of lambs, suggesting that the extra nutrients consumed were prioritized to dams rather than to the components of the gravid uterus.