INCLUSION OF SUGAR-BEET PULP AND CHANGE OF PROTEIN-SOURCE IN THE DIETOF THE WEANED PIGLET AND THEIR EFFECTS ON DIGESTIVE PERFORMANCE AND ENZYMATIC-ACTIVITIES

Twenty-eight 3-week weaned piglets were randomly assigned in a 2 x 2 f actorial arrangement to one of four dietary treatments based on wheat and containing either 0 or 120 g kg(-1) sugar-beet pulp (SBP) in combi nation with either soybean meal (SBM) or soluble fish protein concentr ate (SFPC) for 5 weeks. The effect of diet was evaluated in a digestib ility and N balance trial. Pancreatic and intestinal enzyme activities were measured after piglet slaughter at 56 days of age. After a 7-day adaptation period to the diets, total tract digestibility (TTAD) was measured. Piglets were then surgically prepared with an ileo-rectal an astomosis and after a recovery and refeeding period were used for the ileal apparent digestibility (IAD) measurement of the same diets. No e ffect of SBP level was observed on TTAD of major dietary components. H owever, the use of SBM instead of SFPC decreased TTAD of energy from 8 9.0 to 86.2% and that of nitrogen from 88.1 to 85.0% (P < 0.001). The inclusion of SBP and SBM increased TTAD of fibre components (P < 0.001 ). The IAD of major dietary components was reduced with the inclusion of 120 g kg(-1) of SBP (P < 0.001), from 80.5 to 72.7% for energy and from 78.9 to 73.3% for nitrogen. The use of SFPC increased the IAD of energy and nitrogen from 73.6 to 79.6% and from 74.1 to 78.1% (P < 0.0 1), respectively. IAD of fibrous components was low and generally sign ificantly lowered by the inclusion of SBP. The difference in the respo nse of TTAD and IAD to the addition of SBP in the diet was associated with a significant increase in post-ileal digestion and disappearance of energetic, nitrogenous and fibrous compounds in the hindgut also su pporting a beneficial effect on daily weight gain. In intact piglets t he N retention was significantly higher for both diets containing SBP or SBM, as opposed to a lower retention during the IAD period. The act ivity of pancreatic lipase was increased (P < 0.01) and those of alpha -amylase and proteolytic enzymes were unchanged with the inclusion of SBP in the diet. Similarly, the activities of dipeptidyl peptidase IV (P < 0.05), N-aminopeptidase and alkaline phosphatase (P < 0.01) in th e mucous of the ileum were increased with. the inclusion of SBP in the diet. The substitution of dietary SFPC for SBM reduced the activity o f pancreatic trypsin (P < 0.10), chymotrypsin and lipase (P < 0.05), a s well as that of ileal gamma-glutamyl transferase (P < 0.05). The inc lusion of SBP in diets leads to a better development of the digestive function and to a beneficial effect on performance of the recently wea ned piglet. (C) 1997 Elsevier Science B.V.