Forages in diets for growing pigs 1. Nutrient apparent digestibilities and partition of nutrient digestion in barley-based diets including lucerne and white-clover meal

The present study was undertaken to determine the Heal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a barley-based diet which included either lucerne or white-clover meal (proportionately 0·10 and 0·20). The experiment was conducted as a 5 × 5 change-over design with growing pigs fitted with simple t-shaped cannulas posterior to the ileo-caecal valve. The Heal and total tract apparent digestibilities of organic matter (OM), crude protein, crude fat, nitrogen-free extractives and energy were significantly reduced ivith increasing inclusion of lucerne and white-clover meal in the diet ( P < 0·05). The total tract apparent digestibility of total fibre (TF) was significantly reduced with lucerne meal inclusion ( P < 0·05), while the Heal apparent digestibility of TF was unaffected by lucerne and white-clover meal inclusion. Hindgut apparent digestibility (proportion of total tract apparent digestibility) of OM and energy was approximately 0·10, 0·70 and 0·70 for barley, lucerne and white-clover meal, respectively. Both the Heal and total tract apparent digestibility of OM and energy were significantly higher for the control diet compared with lucerne and white-clover meal ( P < 0·05). There was also a significantly higher apparent digestibility of OM, TF, crude fibre and energy in the total tract for white-clover meal compared with lucerne meal ( P < 0·05). For neutral- and acid-detergent fibre a similar pattern was observed, however the effect was not significant. The dietary digestible energy content was significantly reduced (F < 0·05), both at the ileum and over the total tract, with increasing inclusion offorage meal.