Chemical composition and ruminal kinetic of neutral detergent fiber of corn and sorghum silages

Abstract

The aim of this work was to evaluate the chemical composition and neutral detergent fiber (NDF) degradation of corn and sorghum silages with different percentages of corn cob and panicles, as the following treatments: corn silage with 0% of corn cob; corn silage with 25% of corn cob; corn silage with 50% of corn cob; corn silage with 75% of corn cob; sorghum silage with 0% of panicle; sorghum silage with 30% of panicle; sorghum silage with 60% of panicle; sorghum silage with 90% of panicle. The treatment effect on the NDF in situ degradation was evaluated by the nylon bag technique, using four Holandês-Zebu crossbreed steers, fitted with a ruminal cannula. Dry matter (DM) content of the sorghum silage increased progressively with to addition of 0, 30, 60 and 90% of panicles, presenting 18.37, 35.20, 42.80 and 59.85% of DM, respectively. Similar behavior was observed with the corn silages with values of 19.36; 24.48; 30.96 and 38.48% of DM for treatments with addition of 0, 25, 50 and 75% of corn cob, respectively. The highest content of crude protein (CP) of the sorghum silage were reached in the treatments with 60% (9,39%) and 90% (9,93%) of panicles. The NDF values of sorghum and corn silages decreased with the increase of panicle and corn cob in the sorghum and corn silages, respectively. The estimated NDF effective degradability, considering a passage rate of 5%/h, of the corn silages were 60.28 (0% of corn cob addition); 58.18 (25% of corn cob addition); 55.30 (50% of corn cob addition); 54.00 (75% of corn cob addition) % and for the sorghum silages, 58.22 (0% of panicle addition); 50.01 (30% of panicle addition); 51.51 (60% of panicle addition) and 45.25 (90% of panicle addition) %. The use of 90% of panicle and 75% of corn cob promoted lowest NDF degradation of sorghum and corn silages, respectively.