Determination of In vitro Nutrient Digestibility of Silage based Diets with Varying Levels of Crude Fibre using Pig Faecal Inoculum

Abstract

Background: The in-vitro nutrient digestibility and fermentation mimicking gastrointestinal process of pigs is a convenient method for rapid and cheaper measurement of degradation of feed ingredients. In the present study silage based diets containing varying levels of crude fibre were subjected to in vitro digestibility evaluation using pig faecal inoculum to determine the best crude fibre level for feeding pigs. Methods: Eight diets were prepared namely, B1, B2, V1, V2, V3, M1, M2 and M3 having 6.28, 8.43, 8.03, 10.0, 11.96, 8.17, 10.31 and 12.06 per cent crude fibre (on dry matter basis) respectively, where diets B1 and B2 were basal diets, V1, V2 and V3 contained vegetable waste silage; M1, M2 and M3 contained maize silage -as additional fibre source. An in-vitro study was carried out to investigate the nutrient digestibility of diets involving enzymatic hydrolysis and fermentation using pig faecal inoculum. Result: The in-vitro total tract digestibility (IVTTD) of dry matter (DM), crude protein (CP) and organic matter (OM) was significantly higher (P less than 0.001) in B1 diet than the other diets. The digestibility of DM, CP and OM of B2 diet was also significantly higher (p less than 0.001) than the M2, M3, V2 and V3 diets but comparable to M1 and V1 diets. The IVTTD of crude fibre (CF) was higher in V3 diet (25.85%) and lowest (P less than 0.001) in M1 diet (11.65%) and both showed a highly significant (P less than 0.001) difference (to other diets. The DM, CP and OM digestibility were significantly higher (P less than 0.001) in the diets containing normal fibre sources than silage containing diets. Cumulative gas production (ml/0.5g feed) at 24 h of in-vitro fermentation were significantly higher (P less than 0.001) in B2 (34.95) and B1 (31.00) diets than other diets. As the CF level in diets increased from 6 to 12%, the digestibility of nutrients linearly decreased except CF digestibility. It was revealed from the study that the level and sources of crude fibre in diets influenced the digestibility of nutrients.