Effects of acetic, propionic and butyric acids given intraruminally at different molar proportions or individually on rumen papillae growth and IGF-I and IGFBP-3 in plasma, liver and rumen tissue in growing sheep nourished by total intragastric infusions

Two experiments were conducted to evaluate effects of acetic, propionic and butyric acids given intraruminally at different molar proportions or individually on the rumen papillae growth and insulinlike growth factor-I (IGF-I), IGF binding protein-3 (IGFBP-3), growth hormone (GH) and insulin in plasma and/or tissues in growing sheep nourished by total intragastric infusions. The animals were daily infused with volatile fatty acids (VFA) mixtures at different molar proportions or individual VFA, casein, glucose and corn oil for a total of 1.2 times of maintenance requirement of energy and protein for 12 days. At the end of each experiment, the sheep were slaughtered and blood and tissue samples were obtained for determination of rumen papillae growth and hormones mentioned above. The present study indicated that the papillae growth and IGF-I concentration in rumen tissue of growing sheep nourished by intragastric infusions were not affected significantly by VFA mixtures with different molar proportions or by acetic, propionic and butyric acids individually (P > 0.05) when they were supplied at the same energy level and the synthesis and secretion of IGF-I could be more associated with the energy level rather than energy source of VFA.