The Effect of Intra-Ruminal Infusion of Saturated and Unsaturated Fatty Acids on Rumen Outflow Rate in West African Dwarf Sheep

Abstract

This study investigated the effect of different proportional combinations of a saturated fatty acid (Palmitic acid, PA) and unsaturated fatty acid (Linolenic acid, LA) on rumen outflow rate (r) in West African dwarf (WAD) sheep. A 5x5 Latin square experimental model of five sheep and five combination proportions of palmitic and linolenic acids were used for the study. The combinations were 70% palmitic acid+30% linolenic acid, 30% palmitic acid+70% linolenic acid, 50% palmitic acid+50% linolenic acid, 100% palmitic acid+0% linolenic acid, 0% palmitic acid+100% linolenic acid and were designated groups A, B, C, D and E respectively. An additional group of four adult WAD sheep that did not receive any fatty acid or their combinations served as the control. The results of the study showed significant (p<0.05) decrease in the rumen outflow rate at all proportions of the fatty acid infusion into the rumen compared to an outflow rate of  0.088 l/hr in the control. Within treatments however, the outflow rate at high proportions of unsaturated fatty acid (groups E and B) were significantly (p<0.05) decreased to 0.002 and 0.009 L/hr respectively compared to the outflow rates of 0.021 and 0.024 L/hr in groups A and D (i.e. 70 and 100% proportions of saturated fatty acids) respectively. The study generally demonstrated that rumen outflow rate was reduced as concentrations of unsaturated fatty acids within the rumen increased causing slowing or reducing effect on the outflow rate. This observation could be useful in choosing the dietary proportion of fatty acids suitable for ruminants since outflow rate is very critical to the kinetics of ruminant digestion.