DIFFERENTIAL-EFFECTS OF FEEDING FERMENTABLE CARBOHYDRATE TO GROWING PIGS ON PERFORMANCE, GUT SIZE AND SLAUGHTER CHARACTERISTICS

Thirty-five gilts grown between 18 and 55 kg live weight were used to examine the effects of feeding fermentable carbohydrate on voluntary f ood intake, performance, carcass characteristics, and large intestinal growth. Five diets were used. The first diet contained steam-flaked s orghum and a supplement based on animal protein sources and 40 g/kg so ya-bean meal (diet SAP). Using this diet as a base, three other diets contained either (i) guar gum, a source of soluble non-starch polysacc haride (NSP) (diet SAP + S-NSP), (ii) Novelose(TM), a source of resist ant starch (RS) (diet SAP + RS), and (iii) a combination of both S-NSP and RS (diet SAP + S-NSP + RS). The final diet (diet WBL) was based o n wheat, barley and Australian sweet lupins. Diets (i), (ii) and (iii) were formulated such that the concentrations of soluble NSP, oligosac charide and RS were similar to those contained in diet WBL. There was no relationship (P > 0.05) between voluntary food intake and indices o f hind-gut fermentation, although pigs given diets SAP + S-NSP and SRP + S-NSP + RS took longer to reach the slaughter weight of 55 kg (P < 0.001) and converted food less efficiently than pigs given other diets (P < 0.001). An increased intake of S-NSP (R-2 = 0.842, P < 0.05) and S-NSP + RS (R-2 = 0.805, P < 0.05) was positively correlated to an in creased (empty) weight of the large intestine. A significant negative relationship (R-2 = 0.78, P < 0.05) existed between the daily intake o f S-NSP + RS and dressing proportion, such that each gram increase cau sed a 0.25 g/kg decrease in the dressing proportion of pigs. No such r elationships existed between the daily intake of soluble NSP, insolubl e NSP, or RS (P > 0.05) with dressing proportion. These data suggest t hat the sources of fermentable carbohydrate used in this study, i.e. s oluble NSP and RS, may not significantly depress voluntary food intake but can affect performance and have a significant effect on large int estinal growth and dressing proportion.