FORAGES IN DIETS FOR GROWING PIGS 2 - NUTRIENT APPARENT DIGESTIBILITIES AND PARTITION OF NUTRIENT DIGESTION IN BARLEY-BASED DIETS INCLUDINGRED-CLOVER AND PERENNIAL RYEGRASS MEAL

Growing pigs fitted with simple t-shaped cannulas posterior to the ile al-caecal valve were used in a change-over design experiment (5 x 5) t o determine the ileal and total tract apparent digestibility and hindg ut disappearance of dietary components and energy in a barley-based di et with increasing inclusion of either red-clover or perennial ryegras s meal (proportionately 0.10 and 0.20). The total tract and ileal appa rent digestibilities of organic matter (OM), crude protein (CPI, nitro gen-free extractives (NFE) and energy were significantly reduced with increasing inclusion of red-clover and perennial ryegrass meal in the diet (P < 0.05). For all fibrous components (total fibre (TF), neutral -detergent fibre (NDF), acid-detergent fibre (ADF) and crude fibre (CF )), the ileal apparent digestibility was unaffected by level of fibre inclusion in the diet. Also the total tract apparent digestibility of TF, NDF and CF were unaffected by reel-clover meal inclusion, while in contrast the total tract apparent digestibility of TF, NDF and CF wer e significantly reduced with perennial ryegrass meal inclusion (P < 0. 05). The hindgut disappearance of crude fat, NDF, ADF and CF was not a ffected by forage meal inclusion, whereas the hindgut disappearance of OM, NFE, TF and energy were significantly lower in the perennial ryeg rass meal diets than in both the control diet and the red-clover meal diets (P < 0.05). The total tract apparent digestibility of OM was hig her for the control diet compared with the red-clover and perennial ry egrass meal diets. There was also a significantly higher apparent dige stibility of OM in the total tract for red-clover meal compared with p erennial ryegrass meal (P < 0.05). The ileal apparent digestibility of energy in a barley-based diet with forage meal inclusion decreased pr oportionately by about 0.014, 0.023 and 0.030 units per unit increase of TF, NDF and CF in dry matter, respectively. Correspondingly, for th e total tract energy apparent digestibility, there was a decrease prop ortionately by about 0.010, 0.016 and 0.022 units per unit increase of TF, NDF and CF in dry matter, respectively. Digestible energy content was significantly reduced, as measured at the ileum or over the total tract, with increasing inclusion of forage meal (P < 0.05).