Inhibition of GH Releasing Factor (GRF)-Induced GH Secretion by Intraruminal Infusion of Volatile Fatty Acids (VFA) in Sheep

A VFA mixture solution containing acetate, propionate and butyrate (the molar ratio of acetate, propionate and n-butyrate =61.7:24.3:14.0) was infused into the rumen at various rates (53.5, 107 and 214μmol kg-1 min-1) over 6h to examine the effects on basal and growth hormone-releasing factor (GRF, 0.25μg kg-1)-induced increase in secretion of GH, insulin, glucagon and somatostatin (SRIF) in five castrated male sheep. Intraruminal infusion of the VFA mixture into the 18-h-fasted animals at the rates of 53.5, 107 and 214μmol kg-1 min-1 finally raised the total intraruminal VFA concentration from 91.4 to 100.2 (P>0.05), 175.9 (P