Roughages for growing pigs, with emphasis on chemical composition, ingestion and faecal digestibility

Two experiments, each with 10 gilts of 30 kg initial bodyweight, were set u p to gain experience in feeding three roughages under controlled experiment al conditions. The experiments were designed to establish what proportion o f the total diets the roughages can make up without refusal, and to get pre liminary results on the apparent faecal digestibility of diets containing t hree kinds of roughage. In experiment 1 (exp. 1), the roughage consisted of either fresh or frozen (thawed) clover-grass. In experiment 2 (exp. 2), cl over-grass silage and whole-crop pea-barley silage was studied. The faecal digestibility of gross energy (GE), dry matter (DM), organic matter (OM), d ietary fibre (DF) and crude protein (CP) were measured for pigs fed diets i ncluding these roughages. The three roughages, leaves and stems of clover-g rass and the basal diets were also tested for in vitro OM digestibility. Roughage intake was similar in both experiments. 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 (c ellulose) and xylose were the main constituents of the non-starch polysacch arides (NSP) in the roughages, with whole-crop pea-barley silage having the highest content. The faecal digestibility of NSP was significantly lower f or diets based on whole-crop pea-barley silage compared to clover-grass sil age (exp. 2). In both experiments, the GE, DM, OM and CP digestibility did not differ. The in vitro OM digestibility demonstrated superior values for clover-grass leaves compared to the stems.