Digestibility, metabolic utilization and effects on growth and slaughter traits of diets containing whole ear corn silage for heavy pigs

The effect of dietary inclusion of whole ear corn silage (WECS) on digestibility, metabolic utilization using a respiration chamber system (trial 1) and growth and slaughter performances (trial 2) was studied in heavy pigs. Three experimental diets were fed to pigs in both trials: a control diet (C), based on cereal meals, soya bean meal and wheat bran and two diets containing WECS (15 or 30% DM, 15WECS and 30WECS, respectively) in partly or complete substitution of corn meal and wheat bran. Diets had similar NDF contents (15.2-15.8% DM), while the highest WECS inclusion determined a slight reduction in CP content (from 14.0 to 13.6% DM) and a decrease of P content (from 0.47 to 0.30% DM). Digestibility (6 barrows/diet, 118 kg BW on average) of OM, CP and fat was similar among diets, while P digestibility was lower for 30WECS diet in comparison with C and 15WECS diets (33.5 vs 45.5 and 44.1%, P<0.05). Nitrogen balance was not different among diets, while P retained decreased significantly with the increase of WECS (5.4, 3.7 and 2.2 g/d for diet C, 15WECS and 30WECS, respectively, P<0.001). No significant difference among diets was registered for energy balance. WECS resulted to have 13477 kJ ME/kg DM. In trial 2 (14 barrows/diet, BW range 85-170 kg BW) the feed intake (about 3.4% BW) was not depressed by silage inclusion and the daily gain in whole trial was not different among dietary treatments (from 737 to 774 g/d). The pH of faeces was lower for the WECS diets than the control (7.10 and 7.00 vs 7.40, P<0.01) and the pH measured at 150 kg BW was lower (6.96, P<0.01) than that measured at 130 and 110 kg of BW (7.29 and 7.24, respectively). Slaughter traits were similar among diets except for a higher backfat thickness (30.5 vs 28.1 mm, P<0.05) and a lower lean percentage (46.8 vs 48.3-48.6, P<0.05) for 30WECS treatment in comparison with the other diets. The data obtained indicate that the substitution of cereal meals with WECS do not hamper nutrient utilization and performances of fattening heavy pigs.