Efeito de enzimas fibrolíticas e do teor de matéria seca em silagens de capim-tanzânia sobre os parâmetros ruminais, o comportamento ingestivo e a digestão de nutrientes, em bovinos

The present trial aimed to study the effects of forage wilting or the addition fibrolytic enzymes to the Tanzaniagrass (Panicum maximum Jacq. cv. Tanzania) during the ensiling process or after the silage unloading and before animal feeding. The fermentation and ruminal kinetics parameters, animal ingestive behavior, dry matter intake and in vivo nutrient digestibilities in bovine were measured. Treatments consisted of forage ensiling as described: A - wilted forage without enzymes; B - fresh forage without enzymes; C - wilted forage with enzymes at ensiling (2 L/t wet forage); D - fresh forage with enzymes at ensiling; E - enzymes applied into silage (10 L/t wet silage) 30 minutes before feeding (direct-fed). Silage samples were submitted to chemical analysis and screened for particle size measurements. Five ruminally cannulated Nellore steers were randomly assigned to a 5 x 5 Latin square design and fed with 50% silage total mixed rations diets. The ruminal passage rate of solid (2.23%/hour) and liquid (4.83%/hour) phases were similar for all treatments. The molar concentration (109.62 mM) of total VFAs and ammonia-N (5.6 mg/dL) observed in ruminal fluid were similar across silages diets. The forage wilting determined lower C2:C3 ration in the rumen. The animal ingestive behavior measured as total time (minutes/day) and rate (minutes/DM kg) was not changed with enzymes application, averaging DM eating (247; 24), DM ruminating (426; 43) and DM chewing (673; 67), respectively. Rations containing wilted silages showed less rumination and chewing. The mean DM (47.5 vs. 53.6%), NDF (45.8 vs. 55%) and ADF (45.5 vs. 54.8%) digestibilities were decreased on total mixed rations containing wilted silages. The wilting of Tanzaniagrass or the addition of fibrolytic enzymes resulted in marginal improvement, both in the ruminal parameters or animal ingestive behavior.