Supplementation with live cultures of Aspergillus oryzae and fibrolytic enzyme for dairy cattle: Effects on metabolism, kinetics and rumen ecosystem

Abstract

The cell wall digestibility is the main limiting factor of the nutritional value of forage. Thus, the use of additives which can promote the digestibility of the fiber is very important for ruminants. The aim of this research is to evaluate the effect of supplementation with live cultures of the fungus Aspergillus oryzae and fibrolytic enzyme on fiber digestibility, consumption, kinetic and ruminal ecosystem of dairy cattle fed corn silage. Experiment 1: will be held to evaluate the chemical composition and fermentation characteristics of silage inoculated with doses of exogenous fibrolytic enzyme (0, 1.3 and 2.6 g/kg DM, Fibrozime®, Alltech) in the sugarcane silage process (high and low NDFD) at different storage times (0, 30, 60 and 120d). The design will be completely randomized (CRD), with 24 treatments and 3 repetitions by treatment. Experiment 2: the objective is to evaluate the in vitro dry matter digestibility (IVDMD) and in vitro neutral detergent fiber digestibility (IVNDFD), through fermentative kinetics and the in vitro degradation assay, of corn and sugarcane silage in response to the addition of doses of live cultures of the fungus A. oryzae (0, 1 and 2g) or fibrolytic enzyme (0, 8, 16 and 24g). The design will be in CRD, with 24 treatments and 3 repetitions by treatment. Experiment 3: in order to quantify the effect of the inclusion of A. oryzae, fibrolytic enzyme (best doses obtained in Experiment 2) and combination of both on DM intake, digestion rate and ruminal passage of NDF, ruminal fermentation, and population composition of ruminal bacteria. There will be used eight ruminal-cannulated Holstein cows. The experimental diets will be composed of 50% roughage in DM, containing corn silage. The design will be of two contemporary 4x4 Latin squares, with 4 treatments and 8 repetitions per treatment.