Graded replacement of maize grain with molassed sugar beet pulp modulated ruminal microbial community and fermentation profile in vitro.

BACKGROUND: Molassed sugar beet pulp (Bp) is a viable alternative to grains in cattle nutrition for reducing human edible energy input. Yet little is known about the effects of high inclusion rates of Bp on rumen microbiota. This study used an in vitro approach and the quantitative polymerase chain reaction technique to establish the effects of a graded replacement of maize grain (MG) by Bp on the ruminal microbial community, fermentation profile and nutrient degradation.

RESULTS: Six different amounts of Bp (0-400 g kg-1 ), which replaced MG in the diet, were tested using the in vitro semi-continuous rumen simulation technique. The increased inclusion of Bp resulted in greater dietary content and degradation of neutral detergent fibre (P < 0.01). Further, Bp feeding enhanced (P < 0.01) the abundance of genus Prevotella and shifted (P < 0.01) the short-chain fatty acid patterns in favour of acetate and propionate and at the expense of butyrate. A total replacement of MG with Bp resulted in an increased daily methane production (P < 0.01).

CONCLUSION: Results suggest positive effects of the replacement of MG by Bp especially in terms of stimulating ruminal acetate and propionate fermentation. However, high replacement rates of Bp resulted in lowered utilization of ammonia and higher ruminal methane production. © 2017 Society of Chemical Industry.