In vitro antimicrobial effect of palm oils rich in medium-chain fatty acids against mastitis-causing Gram-positive bacteria

Various pathogens causing mastitis in dairy cattle are of serious concern due to their increasing antibacterial resistance and potential transmission to other cows, calves, and the environment, especially through the milking process. Therefore, alternative approaches to antimicrobial usage in the treatment or control of mastitis in dairy cattle are severely needed. The antibacterial effect of medium-chain fatty acids (MCFAs) is known to be significant for various pathogens, but there is only limited information about the activity of MCFAs on mastitis-causing pathogens. Moreover, no evidence about the antimicrobial effects of palm oils rich in MCFAs, such as coconut, palm kernel, and tucuma oil, can be found in the current literature. The aim of this study was to evaluate the in vitro antibacterial effect of palm oils rich in MCFAs, after cleavage by an exogenous lipase from Mucor javanicus, on bovine mastitis-causing strains (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus uberis) by the broth microdilution method. All tested palm oils exerted antibacterial activity against eight tested bacterial strains in the range of 64-8192 µl/ml with Str. agalactiae being the most sensitive and S. aureus being the most resistant species. The results of the present study demonstrate that palm oils rich in MCFAs can serve as an alternative to the predominantly used predip and postdip procedures in bovine mastitis control, but further in vivo studies are needed to confirm the findings for their possible applications.