Effects of dietary fibrolytic enzymes on chewing time, ruminal fermentation, and performance of mid-lactating dairy cows

• Autor(a) principal: Silva, T. H.
• Data de Publicação: 2016
• Outros Autores: Takiya, C. S., Vendramini, T. H.A., de Jesus, E. Ferreira [UNESP], Zanferari, F., Rennó, F. P.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.anifeedsci.2016.08.013; http://hdl.handle.net/11449/173674
• topic: Cellulase; Chewing activity; Fiber digestion; Neutral detergent fiber; Xylanase

Exogenous fibrolytic enzymes (EFE) can increase ruminal digestion of neutral detergent fiber (NDF) and improve its fermentation for cattle. Twenty-four multiparous Holstein cows (33.72 ± 7.63 kg milk/d and 176 ± 82.27 days in milk – DIM, at the start of the experiment) were used in a replicated 4 × 4 Latin square experimental design. Increasing doses of a commercial product was used to evaluate the effect of xylanase activity (100 units per gram of product) on intake and total-tract digestion of nutrients, sorting index, chewing time, milk yield and composition, N use, and ruminal fermentation. Treatments consisted of 0, 8, 16 or 24 g/d per cow of EFE product mixed into the concentrate. Corn silage was used as forage source. The basal diet had a forage-to- concentrate ratio of 50:50 (dry matter basis). Even though EFE supplementation had a positive linear effect on dry matter and NDF intake, it had no impact on total-tract digestion of nutrients. Moreover, this enzyme promoted a linear increase of the intake of feed with larger particle size (>19 mm) and quadratically affected rumination and chewing activity (hours), reaching the highest values at intermediate doses (8 g/d and 16 g/d). Treatments had no effect on milk yield and composition; however, the N use efficiency was linearly decreased by EFE, reducing thus the ability to synthesize milk and quadratically decreasing N retention. No treatment effect was found on ruminal pH, whereas a negative quadratic effect on ruminal NH3-N concentration was significant. Regarding ruminal parameters, this enzyme supplementation provided linear increased in acetate, propionate, butyrate, and total short-chain fatty acids synthesis. As result, EFE supplementation improved DM and NDF intake, increasing the time spent chewing and ruminating, leading to a greater total short-chain fatty acids production in rumen. Nonetheless, EFE did not improve milk yield and composition of mid-lactating dairy cows.