Effects of calcium oxide level and moisture content on the in situ degradability of the alkali treated and anaerobically stored corn stover

Abstract Text: Corn stover is one of the most abundant agricultural residues in the world. Calcium oxide (CaO) treatment could improve the nutritional value of corn stover. Anaerobic storage is an effective way to keep the treated stover free from molding. The aim of this study was to investigate the in situ degradability of the corn stover treated with different combinations of CaO level and moisture content. Ground stover was treated with different levels of CaO (3%, 5% and 7%) and moisture content (40%, 50% and 60%), then stored under anaerobic condition for 15 days. Four Holstein cows with ruminal cannulas were used to evaluate the in situ ruminal degradability of DM, OM, and NDF (ISDMD, ISOMD, and ISNDFD) of the corn stover. Stover samples were incubated in the rumen for 0, 4, 8, 12, 24, 36, 48, and 72h. Compared with untreated corn stover, CaO-treated corn stover had greater (P < 0.01) ISDMD, ISOMD, and ISNDFD. The moisture content and CaO level affected (P < 0.01) ISDMD, ISOMD, and ISNDFD, but no interaction of main effects existed. The greatest improvements in ISDMD, ISOMD, and ISNDFD occurred when stover was treated with 7% CaO and 60% moisture content; however, no differences (P> 0.01) in these in situ degradability parameters were observed between the stover treated with 5% CaO at 60% moisture content and that treated with 7% CaO at 60% moisture content. When treated with 5% CaO at 60% moisture content, the ISDMD, ISOMD, and ISNDFD of the stover were increased by 31.72%, 34.03%, and 36.50%, respectively. Based on this study, the level of 5% CaO and 60% moisture content was a proper treatment for corn stover.

Keywords: corn stover; calcium oxide; in situ degradability