Thermogenesis, serum metabolites and hormones, and growth in lambs born to ewes supplemented with docosahexaenoic acid

Abstract

Neonatal lamb mortality is a major factor effecting profitability in the sheep industry. Lamb thermogenesis and immunocompetence are key elements in neonatal lamb survival. Research has shown an increase in lamb vigor, when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA). However, the impact of DHA on lamb thermogenesis and immunocompetence has not been investigated. Eighty twin-bearing Targhee ewes were assigned randomly to 1 of 2 supplemental treatments to determine the effects of feeding (DHA) to ewes during late gestation and early lactation on lamb thermogenesis, immunocompetence, serum metabolites and hormones, and lamb growth. Treatments within supplements were: 1) 12 g/ewe daily of the product DHA Gold in the form of algal biomass (ALGAE), and 2) no DHA (CONTROL). Treatment supplements were individually fed daily during the last 30 d of gestation and pen fed (6 pens/treatment, and 6 or 7 ewes/pen) during the first 38 d of lactation. One h after lambing and before nursing, twin-born lambs were weighed, bled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C). Lamb rectal temperatures were recorded every 1 min. After 30 min, lambs were removed from the cold chamber, bled, warmed for 15 min, and returned to their dam. Ewes were bled and colostrum samples collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, non-esterified fatty acids (NEFA), cortisol, leptin and anti-Parainfluenza Type 3 (PI³) titers. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, anti-PI³ titers, and birth weights did not differ between treatments. Thirty-eight-d BW was greater (P = 0.03) in lambs born to CONTROL-supplemented than lambs born to ALGAE-supplemented ewes; however, the colostrum of ALGAE-supplemented ewes had a greater specific gravity (P = 0.05), indicating greater IgG concentrations, than colostrum of CONTROL-supplemented ewes. Supplementation of DHA during late gestation and early lactation had a negative impact on lamb BW and did not affect indices of lamb thermogenesis, but may have improved IgG concentrations in ewe colostrum.