Utilisation of fibre-rich feedstuffs for pigs in Vietnam

This thesis examines the chemical composition and water holding capacity (WHC) of fibrous feeds and evaluates the effects of fibre level, fibre source, particle size and enzyme supplementation on the digestibility, performance, total tract mean retention time (MRT), as well as gut development, morphology, environment and microflora of pigs. The content (g/kg dry matter, DM) of crude protein, ether extract, starch, total sugars and non-starch polysaccharides was found to vary between feedstuffs. The content of individual neutral sugars varied between feed ingredients, with the highest content of arabinose, galactose and glucose in tofu residue, the highest xylose content in brewer’s grain and the highest mannose content in coconut cake. The content of soluble non-cellulosic polysaccharides was positively correlated to the WHC. Pigs (Landrace x Yorkshire, LY) fed a diet containing cassava residue had higher the total tract apparent digestibility (TTAD) of nutrients and average daily gain (ADG) and lower feed conversion ratio (FCR) than those fed a diet containing sweet potato vines. A reduction in particle size and multi-enzyme addition improved the TTAD of dietary components and growth performance in the post-weaning period, but not the in growing period. An increased fibre content in the diet decreased ADG, the nutrient digestibility and MRT, and increased FCR and gut weight. Moreover, there was a possible impact of fibre properties on nutrient digestibility and MRT, but not on gut size. Mong Cai (MC) pigs had a greater relative gut weight and content than LY pigs and a longer MRT, resulting in higher nutrient digestibility. Across diets within breeds the MRT was negatively related to DMI, while the TTAD of nutrients was positively related to MRT. Fibre level and fibre source affected small intestinal morphology, in particular in the ileum. This effect occurred in parallel with fibre-related effects on lactic acid bacteria (LAB) and E. coli counts in the gastrointestinal tract (GIT), and on the gut environment. There were differences between MC and LY pigs in small intestinal morphology, counts of LAB and E. coli along the GIT and gut environment. In short, this thesis shows that fibrous feedstuffs from green plants and agro-industrial by-products can be used in pig diets as common feed ingredients, particularly in indigenous pig diets