Location: Dairy Forage ResearchTitle: Silage extracts used to study the mode of action of silage inoculants in ruminants Author
Submitted to: Scientific and Technical Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2013
Publication Date: 3/27/2013
Publication URL: http://handle.nal.usda.gov/10113/56734
Citation: Muck, R.E., Weinberg, Z.G., Contreras-Govea, F.E. 2013. Silage extracts used to study the mode of action of silage inoculants in ruminants. Agricultural and Food Science. 22(1):108-114. Interpretive Summary: Bacterial inoculants are commonly used in making silages in order to ensure good preservation of the crop in the silo. However, many of these products also increase milk production (when cows are fed inoculated silage) for reasons that are poorly understood. Previous research indicated that some inoculated silages provided more protein to the cow by stimulating the growth of microorganisms in her main stomach. In this study, we looked to see if the factor in inoculated silage was soluble in water or ethanol and therefore could be isolated and identified. However, our results suggest that it is an insoluble substance. If the factor or factors were identified, this could lead to new inoculants that improve how cows use silage. Consequently they would produce more milk while also producing less manure and greenhouse gas per unit of feed, benefiting both the farmer and the environment.
Technical Abstract: Alfalfa and two corn crops were ensiled with and without Lactobacillus plantarum MTD/1 silage inoculant and fermented for 4 or 60 d to assess the effect of the inoculant on in vitro rumen fermentation of the resulting silages. Water and 80% ethanol extracts of the silages with added glucose were also analyzed for effects on in vitro rumen fermentation for 24 h. The inoculant had substantial effects in the alfalfa silage, reducing pH and increasing lactic acid concentration, but little effect on the ensiling of the corn. In vitro fermentation of the wet-ground silages showed little effect of treatment except increased microbial biomass yield (MBY) at 24 h in the inoculant-treated alfalfa silages compared with controls. In vitro fermentation of the water extracts from the alfalfa silages produced no significant differences in fermentation products by treatment with the exception of reduced MBY in the inoculant-treated extracts, indicating the factor affecting in vitro fermentation of the inoculated silages was not in the water extract. The ethanol extracts produced in vitro results that were also not consistent with the in vitro results of the silages. Consequently it appears that the factor in in vitro fermentation of inoculated silages causing increased MBY was in neither the water nor ethanol extracts. However, there is the need for further research to confirm these results.