Digestibility of whole ear corn silage for heavy pigs

The aim of this trial was to determine the digestibility of diets containing whole ear corn silage (ES) for pigs at different stages of growth during the heavy fattening cycle. The ES was included in experimental diets at two levels (15 and 30% on DM, ES15 and ES30 respectively) in substitution for corn meal (C) and six pigs were used in three digestibility trials performed at 35, 85 and 135. kg average live weight (LW, indicated as young, medium grown and heavy pigs, respectively). Each trial was divided into two 15. d experimental periods in a change-over design, with the total faeces collected in the last 5. d. During the first trial the total urine were also collected.The daily dry matter intake (DMI) was restricted to about 3.0-3.4% LW and a small amount of refusals (5% of the DMI) were found in the trial with the heavy pigs only for the ES30 diet. The substitution of C with ES increased the NDF content of diets from 12.7 to 14.0 and to 15.3% DM in diets C, ES15 and ES30. The DM content of faeces decreased regularly with the ES inclusion in all trials, but the reduction was statistically significant only in the trial with the medium grown pigs (33.4, 32.2 and 29.9% DM, respectively for C, ES15 and ES30, P< 0.05). In the trial with the young pigs, the inclusion of ES negatively affected the digestibility of organic matter (OM, 88.4, 87.0 and 84.5%, respectively for C, ES15 and ES30, P< 0.01) and NDF (48.9, 46.3 and 42.2%, respectively for C, ES15 and ES30, P< 0.05). The ES30 diet had a lower (P< 0.05) non structural carbohydrates (calculated as OM-NDF-ether extract-crude protein) digestibility than the other two diets (96.1 vs. 97.1-97.2%) and no differences in N retention or excretion were observed among the diets. Overall, the inclusion of ES in the trial with the young pigs caused a statistically significant reduction (-6%, P< 0.01) of the predicted DE content. In the subsequent trials with the medium grown and heavy pigs, both OM and NDF digestibility and DE content of diets did not change with ES inclusion. In conclusion, ES can be used at levels of 30% on DM at intermediate and final fattening cycle without appreciable decrease in digestibility.