Role of dose-dependent Lactobacillus farciminis on ruminal microflora biogases and fermentation activities of three silage-based rations.

AIMS: The influence of Lactobacillus farciminis on ruminal fermentation characteristics was elucidated in this study. METHODS AND RESULTS: Ruminal fermentation was conducted using maize silage ration (R) and concentrate (C) as 75R:25C, 50R:50C and 25R:75C, supplemented with lactic acid bacteria (LB) at 0, 20 and 30 mg g-1 dry matter substrate and their interaction (1st experiment). The same LB product was used at 0, 20, 40 and 60 mg g-1 dry matter of the mixture (1 : 1) of oat straw and concentrate for 48 h of incubation (2nd experiment). At 24 and 48 h of incubation, LB0 produced the highest biogas and LB20 produced the lowest, whereas at 48 h of incubation LB40 produced the lowest. In ration x LB, LB40 resulted in the highest biogas production, while LB0 had the lowest (P < 0·001) at 8, 10 and 12 h of incubation. Inclusions of LB0, 20, 40 and 60 mg g-1 dry matter resulted in a linear increase (P < 0·003) in the asymptotic biogas production and fermentation parameters in a dose-dependent manner, except in pH which decreased (P = 0·029). CONCLUSIONS: The use of L. farciminis in diet with high level of concentrate without any adverse effect on the pH of rumen fluid to the point of acidosis. Furthermore, in high forage diet, the use of L. farciminis would help to improve the ruminal fermentation digestibility and mitigate ruminal biogas production. SIGNIFICANCE AND IMPACT OF THE STUDY: Using Lactobacillus as a feed additive can improve ruminal fermentation activities by maintaining the stability of pH in the rumen and improving the feed utilization through manipulation of the microbial ecosystem.

Role of diverse fermentative factors towards microbial community shift in ruminants.

Besides the liver, rumen is one of the most important components of metabolism in ruminants. However, the microbes residing in the rumen are influenced by several complex factors such as diet, which result in fluctuations in the rumen pH. Rumen pH affects feed intake and feed digestibility, subsequently causing microbial shift in the individual members of microbial community residing in the foregut and hindgut. This in turn causes an increase in lipopolysaccharide concentration, among other factors, in the gut fluid and animal blood. Irrespective of diet fed to animals, Firmicutes would probably be the most dominant in high grain diet while Bacteroidetes are dominant in hay diet, and both have a relative abundance of about 80% or more at times. The shift in microbial population is not limited to adult ruminants alone but also occur in calves. Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria were the most abundant in both hay and concentrate diet of newly weaned calves. Prolonged, depressed pH, causes subacute ruminal acidosis. This leads to compromise in the integrity of both foregut and hindgut of ruminants, eventually causing structural changes in the gut physiology. Furthermore, diet containing C-12:0 and C-14:0, which are medium-chain fatty acids, were toxic to rumen protozoa. Phytochemical content in some plant residues when fed to animals also causes shift in microbial population. Therefore, foregut and hindgut pH stability is important for ruminant health and for optimal productivity.