RESUMEN
Medium-chain fatty acids (MCFAs) have antialgal, antibacterial, antifungal, antiprotozoan, and antiviral activities. However, antibacterial activities of MCFAs in the hindgut of pigs and cattle are still unknown. We report the effects of the supplementation of MCFAs on fecal bacteria of pigs, lactating cows, and Japanese Black calves. Lactobacillus spp., Bifidobacterium spp., eaeA(+) Escherichia coli, Salmonella spp., Campylobacter jejuni, and Clostridium perfringens in the feces of animals were quantified by real-time PCR assay. There was no significant increase or decrease in Lactobacillus spp. and Bifidobacterium spp. in the three animals. In the pig feces, eaeA(+) E. coli was reduced to less than a third in the treatment group (P < 0.01). C. jejuni in the pig feces was also significantly less in the treatment group compared with the control (P < 0.01). In the lactating cow, eaeA(+) E. coli was reduced to one fifth of that in the control (P < 0.01). Salmonella spp. was halved in calf feces (P < 0.01). Thus, a reduction in Gram-negative pathogenic bacteria was observed. In conclusion, supplementation of a MCFA calcium soap in the diet would be beneficial to growing pigs, lactating cow, and calves by reducing pathogenic bacteria.