Influence of individual or mixed cellulase and xylanase mixture on in vitro rumen gas production kinetics of total mixed rations with different maize silage and concentrate ratios.

This study assessed the effects of cellulase, xylanase, and their mixture (1:1, v/v) on in vitro rumen fermentation of five mixed rations with different maize silage (F) to concentrate (C) ratios (0F:100C, 25F:75C, 50F:50C, 75F:25C, 100F:0C). Samples were incubated using rumen inoculum from Brown Swiss cows fed ad libitum a total mixed ration of concentrate and alfalfa hay (1:1). Gas production (GP) was recorded after 2, 4, 6, 8, 10, 12, 24, 36, 48, and 72 h of incubation. Interaction effects (P < 0.0001) were observed between type of ration and enzyme for discrete lag time prior to GP. Ration type affected asymptotic GP (linear and quadratic, P < 0.0001) and in vitro GP at 24 h onward. Moreover, rations affected pH (linear and quadratic, P < 0.0001), dry matter degradability (quadratic, P = 0.05), metabolizable energy (linear, P = 0.038), short-chain fatty acids (linear, P = 0.0005), gas yield from truly digested dry matter at 24 h (linear, P = 0.0026), and microbial crude protein yield (linear, P = 0.0264). The most effective rations for in vitro GP during different times differed between different measured parameters. Enzyme administration was more effective when the ratio of maize silage was increased. [ABSTRACT FROM AUTHOR]