Roughages for Growing Pigs, with Emphasis on Chemical composition, Ingestion and Faecal Digestibility

Summary

In 2 experiments, 10 gilts (30 kg initial liveweight) were given a basal diet with fresh or frozen/thawed clover-grass, clover-grass silage or whole-crop pea-barley silage. The faecal digestibility of gross energy (GE), DM, organic matter (OM), dietary fibre (DF) and CP were measured. The 3 roughages, leaves and stems of clover-grass and the basal diets were also tested for in vitro OM digestibility. Roughage intake was similar in both experiments and the average proportion of roughage ingested was 18-19% of DM. There were no differences between fresh and frozen/thawed clover-grass nutrient digestibility values. Glucose (cellulose) and xylose were the main constituents of the non-starch polysaccharides (NSP) in the roughages, with whole-crop pea-barley silage having the highest content. The faecal digestibility of NSP was significantly lower for diets based on whole-crop pea-barley silage than clover-grass silage. In both experiments, the GE, DM, OM and CP digestibility did not differ. Clover-grass leaves had higher in vitro OM digestibility than the stems.