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Two different experiments were conducted (Exp 1 and Exp 2). In Exp 1, digestion experiment, six sows fitted with a T-cannula in the terminal ileum were used to evaluate three different diets during three periods; animals were allocated in metabolic cages. In Exp 2, six sows were placed in a respiration chambers and the six animals were fed the same three experimental diets as in the Exp 1. The three experimental diets fed to the sows were: a low-fibre control diet and two generic high dietary fibre diets (high fibre 1 and high fibre 2) with different proportions of soluble and insoluble dietary fibre. The low fibre diet (15% dietary fibre) was formulated on wheat and barley and the 2 high fibre diets (40% of dietary fibre) were based on wheat and barley and supplemented with different coproducts (sugar beet pulp, potato pulp, pectin residue and brewers spent grain). In Exp 1 the experimental period consisted in 7 days of adaptation to the new diet, followed by 3 days faecal collection and 3 days of quantitatively ileal digesta with 1 day between collections. In Exp 2, six sows were placed in metabolic cages in the respiration chambers, where gas exchanges and movements were measured for 48 h, urine and faeces were also collected to calculate energy metabolism.
It was observed that the dietary fibre levels influenced the ileal flow of most nutrients, in particular carbohydrates which increased from 190 g/d when feeding the low fibre diet to 539 g/d when feeding the high fibre diets; this was also reflected in the digestibility of organic matter and carbohydrates (P<0.05). Feeding high fibre diets resulted in greater CH4 production related to the amount of carbohydrates (r=0.79) and organic matter fermented in the large intestine (r=0.72), but no difference in heat production were observed. Retained energy was decreased when feeding a high fibre diet (a 41% of dietary fibre and 11% soluble dietary fibre) compared with a low dietary fibre diet (16% dietary fibre; 4.8% soluble dietary fibre). It was also observed that the activity of the animals was reduced (P<0.05) when feeding with a high dietary fibre diet (41% dietary fibre and 11% of soluble dietary fibre).
It is concluded that feeding diets with high content in dietary fibre increases the amount of fermentable carbohydrates but reduces the retained energy and animal activity.
A Serena, H Jorgensen and KE Bach Knudsen (2008), Journal of Animal Science, 86: 2208-2216
