Influence of endophyte infected fescue on serum concentrations of leptin in female ruminants

The objective was to determine whether leptin played a role in abnormal reproductive function in ruminant females fed endophyte-infected (EI) tall fescue. Cow-calf pairs grazed endophyte-free (EF) or EI tall fescue starting in mid-April (early spring) for 2 years and yearling ewes were fed an EF or EI fescue seed diet for up to 37 days to examine signs of fescue toxicosis and measure serum concentrations of leptin. Signs of fescue toxicosis were present in EI fed cows and ewes. Serum concentrations of leptin were reduced in cows grazing EI compared with EF fescue from mid- to late May in the first year grazing trial, but not the second and were similar between EF and EI-fed ewes. Leptin concentrations also were reduced in cows which grazed EI fescue in the first year and lost a pregnancy before 126 days of gestation compared with cows that maintained. The mechanisms of increased embryonic losses in cows experiencing fescue toxicosis is not known, but may be associated with reduced nutritional status of the pregnant animal. Keywords: cows, ewes, fescue, leptin, reproduction