Characterization of and improvement in the nutritional value of wheat millrun for swine.

摘要

Little information exists on the nutrient composition and value of wheat millrun as an opportunity feedstuff for swine. The nutritional value of millrun and ways to improve it were investigated in 4 studies. In Chapter 1, 2 experiments were conducted to determine if dietary enzymes increased the digestibility of nutrients bound by non-starch polysaccharides (NSP) and phytate in millrun and consequently improved performance. Xylanase improved (P 0.05) total tract energy digestibility, DE content and G:F. Phytase reduced (P 0.05) ADFI, and xylanase tended to reduce ( P = 0.07) ADFI. In Chapter 2, effects of xylanase on nutrient digestibility were studied in a wheat control diet and 5 diets containing 30% by-product (millrun, middlings, shorts, screenings, and bran). Xylanase improved ( P 0.05) total tract energy digestibility of the millrun, shorts, screenings, and bran diets. Xylanase did not affect hindgut fermentation but reduced (P 0.05) hindgut fermentable DE. In Chapter 3, effects of supplementing xylanase and (or) phytase on nutrient digestibility, digesta passage rate and mean digesta retention time (MRT) of a wheat-based diet containing 20% millrun were investigated. The enzymes interacted to increase (P 0.05) total tract nutrient digestibility and DE content of the negative control diet, but did not affect passage rate and MRT. In Chapter 4, effects of xylanase and phytase supplementation on site of nutrient digestibility in weaned pigs, pH content in the gastrointestinal tract and on growth performance were studied in diets with reduced nutrient specifications (negative control: NC). Xylanase improved (P 0.01) energy digestibility of the NC in the mid jejunum and over the total tract by 63.0 and 4.6%, respectively. Diet tended to reduce (P = 0.074) the pH content of the upper small intestine, and phytase raised ( P 0.01) the pH content of the upper mid small intestine. Both enzymes improved total tract DE content and performance of weaned pigs. Phytase inclusion led to a more rapid return to alkaline conditions in the upper part of the small intestine. In conclusion, the nutritional value of millrun can be improved with exogenous enzymes thereby improving its status as an opportunity feedstuff in swine diets.