Digestibility and Physicochemical Characteristics of Tambaqui Waste Biological Silage Meal Included in Commercial Layer Diets*

This study aimed at evaluating the effects of the physicochemical and nutritional characteristics of a biological silage meal made of tambaqui waste on dietary nutrient apparent digestibility and energy metabolism of commercial layer diets. Seventy-two 61-week-old Hisex White hens were assigned according to a completely randomized experimental design in two treatments: control diet and diet with 5% tambaqui waste biological silage meal (TWBSM), with six replicates of six birds each. The ensiled biomass presented grey brown color, acid aroma, viscous texture, 5.27±0.016pH, 96.28% dry matter (DM), 33.29% crude protein (CP), 33.65% ether extract (EE), 14.37% ashes, 13.63% non-nitrogen extract (NNE), 65.16 g.kg-1 calcium (Ca), 22.90 g.kg-1 phosphorus (P), and 5,666.07 kcal.kg-1 gross energy (GE). Higher (p>0.05) coefficients of apparent digestibility of DM, crude fiber, EE, and ash, and higher coefficient of GE metabolizability were obtained in the diet with 5% TWBSM. Due to its high CP content (33.29% on DM basis), TWBSM may be considered a protein feedstuff. Although no differences in CP digestibility (p>0.05) were detected, TWBSM presented high CP digestibility than the control diet due to proteins hydrolysis as a result of lactic fermentation by microorganisms during the ensilage process, yielding autolysed proteins of high biological value. Our results indicate that the biological silage meal produced from the residual biomass of tambaqui can be included up to 5% in commercial layer diets as it has good nutrient digestibility, and therefore, may potentially be used as a dietary energy and protein source.