Supplementation of pig starter diets with carbohydrate-degrading enzymes - stability, activity and mode of action

• Main Author: Johan Inborr
• Format: Article
• Language: English
• Published: Scientific Agricultural Society of Finland 1994-12-01
• Series: Agricultural and Food Science
• Online Access: https://journal.fi/afs/article/view/72724
• ISSN: 1459-6067; 1795-1895

A total of five experiments were conducted to investigate the stability of feed enzymes to steam pelleting and the proteolytic conditions in the gastrointestinal (GI) tract of pigs and poultry, and to try and elucidate the mechanisms behind the improved performance of pigs fed enzyme-supplemented barley/wheat-based diets. The results of the pelleting stability experiment showed that the commercial feed enzyme employed maintained most of its activity in conditioning temperatures up to 85°C.Furthermore, it became evident that measuring enzyme recovery in pelleted feeds by in-vitro assay methods underestimated the actual activity. For this purpose in-vivo models such as that based on gut viscosity measurements in broiler chickens gives a more accurate estimate. Gut viscosity also correlated highly with live weight gain (r2=0.624) and feed utilisation (r2=0.616) of broiler chickens. The in-vitro incubations using conditions similar to those of the GI tract showed that enzymes are not readily denatured and inactivated in such conditions and indicated that wheat and wheat gluten, and possibly similar feed ingredients, may help to maintain the activity longer either due to their buffering capacity or by providing substrates for the enzymes. This was supported by the results of the in-vivo measurements. In the stomach of pigs, 10-20per cent of the xylanase and β-glucanase activities added to the diets could still be recovered 4 hours after feeding. In the ileum, proportionally more added enzyme activities were recovered between 4 and 6 than 0 and 2 hours after feeding. In broiler chickens fed an enzyme-supplemented barley-based diet, β-glucanase was fully recovered in the proximal part of the small intestine, giving further proof of the stability of the enzymes employed to the conditions of the GI tract. When a mixture of fibre- and starch-degrading enzymes were added to a diet based on wheat and barley, β-glucan, starch and dry matter digestibilities were significantly (P