Microbial inoculant and an extract of Trichoderma longibrachiatum with xylanase activity effect on chemical composition, fermentative profile and aerobic stability of guinea grass (Pancium maximum Jacq.) silage

The objective of this study was to determine the effects of increasing dose of a microbial inoculant alone or in combination with a Trichoderma longibrachiatum extract with xylanase activity on total losses, chemical composition, fermentative profile, microbiological quality and aerobic stability of guinea grass (Panicum maximum Jacq. cv. Mombasa) silage. Sixty minisilos (0.022 m(3)) were used in a 3 x 2 factorial experiment, composed by three levels (0, 4 or 8 g . t(-1) of fresh forage) of microbial inoculant (INO) and two levels (0 or 1 IU . g(-1) of fresh forage) of enzyme product (ENZ). INO consisted of Lactobacillus plantarum at 4 x 1010 cfu . g(-1) and Pediococcus acidilactici at 4 x 10(10) cfu . g(-1). Silos were opened after 60 days. The combination of INO8 with ENZ caused the lowest gas losses. ENZ increased silage crude protein content, as well as the dry matter and neutral detergent fibre (NDF) in vitro digestibility. INO doses exerted a positive quadratic effect on NDF in vitro digestibility. ENZ addition increased acetic acid concentration, while INO treatments linearly decreased acetic and butyric acid concentrations and linearly increased lactic and propionic acid concentrations in silage. INO exhibited a negative quadratic effect on pH and NH3-N concentration of guinea grass silage and positive linear increase in the counts of anaerobic bacteria. Combinations of ENZ and INO8 decreased silage aerobic stability. Although there was observed no combined effect of ENZ and INO on silage chemical composition and fermentative profile, they exerted positive influence on NDF in vitro digestibility of the guinea grass silage when added alone (ENZ and INO at a dose of 4 g . t(-1)).