Carbon balances for in vitro digestion and fermentation of potential roughages for pregnant sows

• Published in: Animal feed science and technology 2003-11, Vol.110 (1), p.159-174
• Main Authors: Becker, P.M, van Gelder, A.H, van Wikselaar, P.G, Jongbloed, A.W, Cone, J.W
• Format: Article
• Language: English
• Subjects: Ad libitum feed intake; Animal productions; Biological and medical sciences; Dietary fibre; Feed and pet food industries; Food industries; Fundamental and applied biological sciences. Psychology; Gas production technique; Nutrition; Pregnant sows; Roughage; Short-chain fatty acids (SCFA); Terrestrial animal productions; Vertebrates
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2003.07.001

Ad libitum feeding of pregnant sows requires satiating, intake-restricting feed components to prevent sows from getting excessively fat. Because hindgut fermentation starts only after and proceeds much slower than enzymatic digestion in the small intestine, fermentation products might, as nutrients, induce a prolonged physiological satiation of sows. To simulate hindgut fermentation and determine the fermentative release of short-chain fatty acids (SCFA) in vitro, gas production tests (GPTs) were performed with different raw materials after removal of enzymatically hydrolysable compounds. Fresh feces from sows that received standard sow feed was used as inoculum. Fresh, ensiled, or dehydrated by-products of the food industry (brewers’ grains, liquid yeast feed, maize gluten feed, raw potato chips, potato steam peel, pressed potato pulp, sugar beet pulp (SBP)) and whole-plant products (grass, maize) were tested as individual products. Balances were drawn up of the in vitro flow of organic carbon (OC) to an “ileal” nutrient fraction, a “hindgut” fraction of SCFA and gas, and “fecal” remnants. The OC balances revealed large variations among raw materials in terms of their contribution to the different fractions. Potato steam peel gave the largest “ileal” nutrient fraction (77% of total OC), the lowest was observed with fresh sugar beet pulp (9% of total OC). In the GPT, SBP, and potato pulp brought about the highest “hindgut” SCFA yields (32–49% of total OC), and together with raw potato chips, the highest amounts of gas. Grass products and liquid yeast feed were slower fermented than most by-products. Moreover, whole-plant materials gave larger “fecal” OC portions than by-products, with the exception of fresh and dehydrated brewer’s grains. Together with straw, the latter were the least degradable of all raw materials tested. Among the grass products, dehydrated grass, and among the by-products, raw potato chips left the least “fecal” residues, i.e. they were nutritionally utilized to the largest extent.