Effect of insect-protected maize silage (Bt-MON 810) on feeding value and digestibility of nutrients estimated with wethers

Abstract

The objective of this study was to compare the feeding value of conventional maize silage with its isogenic Bt form in digestibility trial on wethers. In 2006, two maize hybrids, MONUMENTAL (C) and Bt-MON 810 (Bt) were planted at the area of Ivanovice na Hané, Czech Republic under comparable conditions. Maize plants were harvested at soft-dough stage of maturity and ensiled into mini-silos (2 m3 ). Silages were used in a digestibility trial with 10 Suffolk wethers with an average live weight of 45.3 + 1.35 kg that were divided into two groups. The experiment was carried out in two periods of 14 days (7-d preliminary period and 7-d collection period). In the fresh maize forage the content of crude protein in C (74.0 g kg-1DM) was higher than in Bt (71.0 g kg-1 DM, P<0.05) and the content of acid detergent fiber (ADF) was lower in C in comparison to Bt (205.8 vs. 210.1 g kg-1 DM, respectively, P<0.05). Content of nutrients in silages was unaffected by the maize hybrid). No effect of the maize hybrid on fermantation process was observed (P>0.05) except of ethanol content that was lower in C and acetic acid content that was higher in C compared to Bt (P<0.05). Intake of dry matter (DM) was similar in both groups (P>0.05). Digestibility of crude fiber and nitrogen-free extractives was lower in C (34.4 and 74.1 %) than in Bt (40.0 and 76.4 %, respectively, P<0.05). Haematological characteristics of animals were unaffected by the type of silage (P>0.05).