A RAPID ASSAY FOR THE MEASUREMENT OF PROTEIN DIGESTION TO THE ILEUM OF PIGS BY THE USE OF A MOBILE NYLON BAG TECHNIQUE

Pigs were fitted either with a cannula in the stomach or with cannulae in the duodenum and ileum. Twenty-seven feed ingredients were ground through a 1 mm screen and 0.5 g samples were placed in a pouch made from a circle of nylon of 75 mm diameter. Bags were suspended in the stomach of the pigs for 6 h. The bags were then removed from the stomach and placed into the duodenum of other pigs. They were then removed from the ileum and analysed for nitrogen content. The digestibility of the feed ingredients to the ileum was also measured in the conventional manner. Nitrogen digestibility measured in nylon bags was similar to that measured in the conventional manner for fish meal, meat meal, milk and soya-bean meal. For ingredients with a higher fibre content, linseed meal, coconut meal, safflower meal and cottonseed meal, the digestibility measured in nylon bags was lower than that measured in the conventional manner. After correction of the data by regression analysis for the acid detergent fibre content of the protein sources, there was close agreement between nylon bags and ileal digestibility values.