Defaunation effects of medium-chain fatty acids and their derivatives on goat rumen protozoa.

Nine castrated Japanese Saanen goats were used to investigate the effects of saturated fatty acids and their derivatives on the rumen ciliate protozoa. The goats were first fed a test diet composed of 500g of basal diet and 25g of one of the following: caprylic acid (C8), capric acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16) or stearic acid (C18). C10 proved to be the most toxic for the protozoa. Progressively less inhibition was displayed with either an increase or a decrease in the carbon chain length. Second, calcium (Ca) salts and triglycerides (TG) of C8 and C10 were applied. With the feeding of C10Ca or C10TG, the protozoa in the rumen disappeared. The toxic effects of free fatty acids were not alleviated by the derivatives. Third, protozoa other than Epidinium in a mixed-faunated goat disappeared after the feeding of hydrated coconut oil (52% lauric acid). Capric acid and its derivatives are considered useful rumen-defaunating agents. Lauric acid and its derivatives might be used to establish Epidinium mono-faunated animals.