Effect of type of oil and site of administration on the fate of fatty acids in sheep

Safflower oil (S) and methyl myristate (M) were administered in the rumen (R) and abomasum (A) of sheep for 28 days. The digestibility of nitrogen and fiber were not affected by treatment. A larger proportion of fatty acids were digested with SA than with SR while the reverse was found with MR and MA. These differences were reflected in the fecal fatty acid composition. Regardless of treatment, the free fatty acid constituted approximately 75% of the fecal fat. MR and to a lesser extent SR increased the molar % of rumen propionate with a corresponding decrease in acetate. Fatty acid composition of rumen bacteria reflected the composition of the administrated oils. SR resulted in increased stearic and decreased linoleic acids in liver lipids while the adipose tissue remained constant. SA increased linoleic in both tissues. Markedly larger increases in myristic acid were found in adipose and liver lipids with MR compared to MA. Large increases in myristic acid in tissues were associated with decreased linoleic acid.