ADDITIVE EFFECT OF SILAGES MADE OF POULTRY LITTER, SWINE MANURE AND UREA MIXED WITH SUGAR CANE MOLASSES AND BAKERY BY-PRODUCT ON LAMB DIETS

Background: The use of silages from non-conventional sources of nitrogen and soluble carbohydrates in feeding lambs is controversial in terms of nutrient supply; due to the minimum number of studies reported to date of in vitro evaluations that allow measuring its nutritional value in ruminants. Objective: To evaluate the additive effect and fermentation potential of silages plus concentrates in diets for lambs on the in vitro gas production kinetics. Methodology: Six diets (silage + concentrate) were evaluated in a factorial arrangement of 3 N sources (dried poultry litter, fresh swine manure, agricultural urea) × 2 carbohydrate sources (sugar cane molasses, bakery by-product). The diets contained: a) silage (400 g/kg DM) and b) concentrates (600 g/kg DM) based on soybean meal, ground corn, wheat bran, corn stover, fish meal, and vitamin and mineral premix. Average gas production data were analyzed with PROC MIXED and the gas production curves were fitted into the Exponential Logistic model with PROC NLMIXED. Results: The PO+MC (151.87 mL/gas MS) and CF+MC (153.12 mL/gas MS) treatments had higher average gas production during incubation. An additive effect was observed on the maximum asymptote of gas production in the CF+MC (+ 4.26%) and PO+MC (+ 3.75%) diets (P<0.01). Diets based on PO or CF combined with MC and SPP had higher IVDMD, IVOMD, and IVNDFD than the control treatment (UR). Implications: The inclusion in diets for growing lambs of corn stover silage based on rapidly fermentable carbohydrate sources with non-protein nitrogen from pig and poultry excreta in diets for growing lambs has associative effects on nutrient degradability and its fermentation potential in small ruminant feed. Conclusions: The PO+MC treatment has a higher potential for gas production due to the associative effect of its components.