Intravenous glucagon like peptide-1 infusion does not affect dry matter intake or hypothalamic mRNA expression of neuropeptide Y, agouti related peptide and proopiomelatnocortin in wethers

The objectives of the present study were to determine the effects of jugular vein infusions of glucagon like peptide-1 (GLP-1) and dietary fat inclusion on dry matter intake, nutrient digestibility and hypothalamic mRNA concentration of neuropeptide Y, agouti related peptide, and proopiomelanocortin in growing sheep. Thirty-six wethers were used (40.7±3.3 kg BW). Treatments were a control diet (n=11), dietary addition (6% of dry matter) of Ca salts of palm oil fatty acids (n=12), or 6-d jugular vein infusions of 0.155 μg kg^-1 body weight/day of GLP-1 (n=11). Hormone concentrations were measured in jugular vein plasma from samples taken on days 1, 4 and 6. On day 7, the wethers were slaughtered for hypothalamus collection to measure mRNA concentration. The dietary addition of 6% of Ca salts of palm oil increased plasma GLP-1 concentration (P<0.01) and decreased dry matter intake on day 1, but not on day 6 (time×treatment interaction, P<0.05). The infusion of GLP-1 did not change dry matter intake (P>0.20), but increased neutral detergent fibre digestibility (P<0.01). In conclusion, glucagon like peptide-1 infusion or feeding fat did not decrease dry matter intake or affect hypothalamic neuropeptide mRNA concentrations of sheep.