Forages in diets for growing pigs 2. Nutrient apparent digestibilities and partition of nutrient digestion in barley-based diets including red-clover and perennial ryegrass meal

Abstract

AbstractGrowing pigs fitted with simple t-shaped cannulas posterior to the ileal-caecal valve were used in a change-over design experiment (5 × 5) to determine the Heal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a barley-based diet with increasing inclusion of either red-clover or perennial ryegrass meal (proportionately 0·10 and 0·20). The total tract and Heal apparent digestibilities of organic matter (OM), crude protein (CP), nitrogen-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 offibre inclusion in the diet. Also the total tract apparent digestibility of TF, NDF and CF were unaffected by red-clover meal inclusion, while in contrast the total tract apparent digestibility of TF, NDF and CF were significantly reduced with perennial ryegrass meal inclusion (P < 0·05). The hindgut disappearance of crude fat, NDF, ADF and CF was not affected by forage meal inclusion, whereas the hindgut disappearance of OM, NFE, TF and energy were significantly lower in the perennial ryegrass 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 higher for the control diet compared with the red-clover and perennial ryegrass meal diets. There was also a significantly higher apparent digestibility of OM in the total tract for red-clover meal compared with perennial ryegrass meal (P < 0·05). The Heal apparent digestibility of energy in a barley-based diet with forage meal inclusion decreased proportionately by about 0·014, 0·023 and 0·030 units per unit increase ofTF, NDF and CF in dry matter, respectively. Correspondingly, for the total tract energy apparent digestibility, there was a decrease proportionately 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 offorage meal (P < 0·05).