Influence of medium chain fatty acids on selected microbes and on in vitro ruminal fermentation of air-exposed corn silage

Authors: SALINAS-CHAVIRA, JAIME - University Of Tamaulipas; ARZOLAR-ALVAREZ, CLAUDIO - Universidad Autonoma De Chihuahua; Hume, Michael; FONSECA, MOZART - University Of Nevada; RUIZ-BARRERA, OSCAR - Universidad Autonoma De Chihuahua; CASTILLO-CASTILLO, YAMICELA - Universidad Autonoma De Chihuahua; ONTIVEROS-MAGADAN, MARINA - Universidad Autonoma De Ciudad Juarez; JONES, BARBARA - Tarleton State University; Crippen, Tawni - Tc; Poole, Toni; ZÚÑIGA-SERRANO, ARACELY - University Of Tamaulipas; Anderson, Robin

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2024
Publication Date: 9/11/2024
Citation: Salinas-Chavira, J., Arzolar-Alvarez, C., Hume, M.E., Fonseca, M., Ruiz-Barrera, O., Castillo-Castillo, Y., Ontiveros-Magadan, M., Jones, B., Crippen, T.L., Poole, T.L., Zúñiga-Serrano, A., Anderson, R.C. 2024. Influence of medium chain fatty acids on selected microbes and on in vitro ruminal fermentation of air-exposed corn silage. Frontiers in Veterinary Science. 11. Article 1416695. https://doi.org/10.3389/fvets.2024.1416695.
DOI: https://doi.org/10.3389/fvets.2024.1416695

Interpretive Summary: Fermented animal feeds, called silages, are used to preserve the nutritional quality of feeds during storage. Exposure of the silages to air during the feeding period can compromise the preservation quality of the feedstuff by allowing the growth of spoilage and pathogenic microbes, thus risking infection of the animal and the foods they produce. In this study, we tested the antimicrobial effects of natural medium-chain fatty acids commonly found in foods such as coconut and palm kernel oil by adding them, alone or as chemically modified mixtures linked to a stabilizing compound, to air-exposed silage. We observed that in most cases, the medium chain fatty acids linked to the stabilizing compound were more effective in controlling spoilage and pathogenic microbes than when applied individually as free fatty acids. Additionally, we observed that none of the free or stable fatty acid treatments had negative effects on the digestion of the feedstuff when tested in gut contents, simulating the animals digestive processes. This research provides useful information that will help livestock producers better preserve and use their fermented feedstuffs, thereby helping them produce wholesome and microbiologically safe meat and milk for the American consumer.

Technical Abstract: Different medium-chain fatty acids and different chemical forms as treatments of aerobically exposed corn silage on spoilage and pathogenic microbes and rumen fermentation were evaluated in vitro. Treatments were control (no additive), myristate (MY), laurate (LA), monolaurin (MLA), methyl ester laurate (MELA), a blend of mono, di, and triglycerides of laurate (BLA), and monocaprylate (MC). After 24 h of aerobic incubation (37oC), yeast and mold growth were not influenced (P>0.05) with treatments, while the net growth of lactic acid bacteria was decreased, albeit slightly, compared to that of untreated controls (P<0.01) by all treatments in the air-exposed corn silage. Compared with controls, wild-type enterococci were decreased (P<0.01) in MLA, MELA, and BLA. Staphylococcus aureus was reduced (P<0.01) with MLA, MELA, BLA, and MC. Total aerobes showed reductions (P<0.01) with MLA, BLA, and MC. Listeria monocytogenes were reduced (P<0.01) with MELA. Anaerobic incubation (24 h; 39oC) of ruminal fluid (10 mL) with 0.02 g overnight air-exposed MCFA-treated corn silage revealed higher hydrogen accumulations (P<0.01) with MLA or MC than controls. Methane was decreased (P<0.01) solely by MLA. There was an increase (P<0.01) of acetate with MELA or MC; of propionate with MELA or by BLA; and of butyrate with MLA, MELA, BLA, or MC. Total VFA, hexose fermented, and ammonia were increased (P<0.01) with MELA, BLA, or MC. Acetate: propionate ratio was increased (P<0.01) with MC. The results showed that in air-exposed corn silage, all used MCFA had no effect on unwanted yeasts and molds while reducing the wanted lactic bacteria. Modest methane reduction was seen solely with MLA, while the other MCFA had little, if any, detrimental effects on beneficial ruminal fermentation characteristics.