METHODOLOGICAL STUDIES WITH THE MOBILE NYLON BAG TECHNIQUE TO DETERMINE PROTEIN AND ENERGY DIGESTIBILITIES IN FEEDSTUFFS FOR PIGS

Studies were carried out with seven barrows, over the weight range 42 to 90 kg, to evaluate (1) the effect of basal diet on apparent protein digestibility of four feedstuffs (barley, wheat, com gluten feed and soybean meal) determined with the mobile nylon bag technique (MNBT), and (2) the use of the MNBT for determining the digestible energy content of cereal grains (barley, com, oats and wheat). Samples, 0.5 g, ground through a 0.5-mm mesh, were enclosed in nylon bags (25 X 40 mm; 48-mu-m). Following pre-digestion (0.1 N HCl; pepsin 754.8 IU/1; 4 h), four bags of each feedstuff were inserted via a T-cannula placed in the duodenum. The material, remaining in the bags after passing through the digestive tract, was pooled within pig and feedstuff. The results were compared with conventional studies. The composition of the basal diets, which varied in crude protein and fiber content, was not responsible for differences in apparent protein digestibilities (P < 0.05) between the MNBT and conventional method for barley, wheat and com gluten feed. The energy digestibilities in the cereal grains were lower (P < 0.01) when determined with the MNBT rather than the conventional method.