The effect of lactic acid bacteria silage inoculants on the rumen environment – current research status

 

Weinberg, Z.G.¹, Chen, Y.¹, Ben-Ghedalia, D.², Yoseph, E.², Nakbahat, M.² and Miron, J.²

¹Forage Preservation and By-Products Research Unit, Department of Food Science

 ² The Metabolic Unit, Institute of Animal Science, The Volcani Center, Bet Dagan, Israel;

 

 

Abstract

Feeding inoculated silages improved ruminant performance  (live weight gain and milk production) by 3 to 5% in about one half of reviewed studies. The objective of the current study  was to find out how and under what conditions LAB impart beneficial (probiotic?) effects on ruminant performance. For the end in vitro experiments were performed in which wheat and corn silages inoculated  with selected strains of lactic acid bacteria (LAB)  were used, or the inoculants were added directly to control silages (direct fed microbials, DFM). The following results were obtained so far: silage inoculants LAB survive in rumen fluid; when added directly to rumen fluid they resulted in higher pH values as compared with control rumen fluid; LAB silage inoculants and inoculated silages possess anti-bacterial activity that potentially could inhibit detrimental microorganisms in the silage or in the rumen. Some LAB inoculants applied at ensiling or added directly to rumen fluid tended to increase in vitro DM and NDF digestibility of wheat and corn silages, especially after 24 h of incubation along with starch.  However, in other experiments performed in Delaware, L. buchneri alone or in combination of either P. pentosaceus or L. plantarum  did not have any consistent effect on DM or NDF digestibility of various corn and alfalfa silages.

 In vitro experiments performed in Madison with wet ground silage samples revealed that inoculated alfalfa silages reduced ruminal gas production, total VFA and acetate : propionate ratio as compared with control silages. More recent in vitro experiments with alfalfa and corn silages have shown certain inoculants increase in vitro microbial biomass production. More research is warranted to elucidate the interactions between LAB inoculants and rumen microorganisms that would shed light on this beneficial phenomenon.