Avaliação da composição de vários alimentos e determinação da cinética ruminal da proteína, utilizando o método de produção de gás e amônia in vitro

Abstract

Chemical determinations and kinetics studies of nitrogen compounds of 24 concentrate feedstuffs and 10 grasses were made using the concentrations of soluble nitrogen in TCA and gas production. It was used 200 mL of ruminal fluid and 800 mL of medium for 100 vessels. It was used 1.0 g of trypticase and 0.1 mL of microminerals solution to prepare 400 mL of medium. It was used 0.8 g of ammonium bicarbonate and 7 g of sodium bicarbonate to prepare 200 mL of buffer solution and, to prepare 200 mL of macromineral solution, 1.15 g of Na2HPO4 anhydrous, 1.25 g of KH2PO4 anhydrous and 0.1 g of MgSO4.7H2O were weighed. Reducing solution was prepared with 0.64 g of cysteine-HCL, 0.64 g of sodium sulfide and 4 mL of 1N NaOH. The disappearance of nitrogen compounds of feedstuffs was determined at 6 and 12 hours, where 1.875 mg of N was incubated with 0, 33, 67, 100 mg oh starch, 6 mL of medium, 4 mL of ruminal fluid-medium mixture and 0.1 mL of reducing solution using CO2. Data of degradation rates indicated that corn gluten feed, casein, dry grounded peanut grain, cassava rasp, sorghum silage with or without inoculum, corn silage and honeygrass showed the highest rates of protein degradation and the slowest degradation rates were obtained by sugar cane yeast, feather meal, fish meal, broiler litter using wood rind as adsorvent and signalgrass. Estimates of degradation rates of forage feedstuffs were higher than degradation rates estimated previously by an inhibitor method. It is recommended to use 12 hours for incubation of concentrate feedstuffs and 6 hours for grasses.