The Effects of Supplementing EPA and DHA during Late Gestation on Lamb Metabolism and Performance

Fatty acids are involved in the regulation of many physiological pathways and can have lifelong impacts on offspring development and metabolism via maternal supplementation. Therefore, our objective was to investigate the impact of supplementing ewes with a diet enrich in omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahenaenoic acid (DHA) during late gestation on lamb metabolism and performance. Eighty-four gestating ewes were blocked by conception date into group pens with 3 animals per pen and randomly assigned to a diet enriched with monounsaturated fatty acids (MUFA, EnerG II), or the polyunsaturated fatty acids (PUFA, STRATA G113) EPA and DHA during the last 50 days of gestation. With a biohydrogenation rate of 50%, the target dose of EPA and DHA supplemented was 18 mg per kg of metabolic body weight (BW^0.75), with total fat supplementation on MUFA and PUFA being fed at the same percent of the diet. After lambing, ewes and lambs were placed on pasture until weaning at 60 days of age. Lambs born from these ewes were weighed and bled at day 0, 30 and 60. Plasma glucose, non-esterified fatty acid (NEFA) and insulin were measured using colorimetric assays and average daily gain was calculated. An immunoassay was tested to measure the metabolic hormone adropin, measuring parallel displacement and recovery. For insulin and adropin only the day 60 plasma samples were used. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). Lambs born form ewes supplemented with MUFA or PUFA did not have different body weights (BW) (MUFA:15.8 kg, PUFA:16.4 kg; P= 0.22), ADG (MUFA: 0.32 kg/day, PUFA: 0.34 kg/day; P= 0.21), or plasma glucose (MUFA: 93.68 mg/dL, PUFA: 96.47 mg/dL: P= 0.50), NEFA (MUFA: 514.68 mg/dL, PUFA: 493.39 mg/dL; P= 0.52) and insulin (MUFA: 0.22 ng/mL, PUFA: 0.25 ng/mL: P= 0.59) concentrations. Human adropin assays are a valid method to measure ovine adropin concentration. This study suggests that supplementation of ewes with EPA and DHA compared to MUFA during late gestation does not have any significant impact on their offspring up to weaning. Further laboratory analyses will confirm whether the dose EPA and DHA was high enough to increase concentrations of these fatty acids in ewe and lamb plasma. Future research should investigate the potential effects of supplementing higher doses of EPA and DHA to ewes during late gestation and effects on offspring.