Preliminary Finding on Anomalous Cleavage and Degeneration of Intestinal Nematode Eggs (Nematodirus sp.) after Oral Administration of Medium-Chain Fatty Acid in Calves

Medium-chain fatty acids (MCFAs) consisting of 8 to 12 carbons are knowns exhibit antimicrobial activity against bacteria and gut protozoa. However, little information is available on their effect in helminthes. The effect of MCFA on an intestinal nematode (Nematodirus sp.) was therefore evaluated in four calves (4 to 11 month old). Edible fat containing MCFA was administered into the abomasum of the calves by practical stimulation of the reticular groove reflex for 5 days, and the resulting fecal egg shedding was examined. Although MCFA had a weak effect on fecal egg number of Nematodirus sp., morphologically anomalous eggs were observed. Anomalies manifested as degenerated eggs with ova granulation or shell rupture, irregular monocellular egg, and disproportional cleavage at the 2-, 4-cell and subsequent stages, despite normal shedding at 8- or 16-cell stages in most cases. Thus, MCFA administration brought cleavage disturbance and degeneration of Nematodirus sp. eggs.