FEEDING VALUE AND PRESERVATION OF HIGH MOISTURE GRAIN TREATED WITH SULFUR DIOXIDE

Abstract

Five experiments were conducted to evaluate the effectiveness of sulfur dioxide as a moist grain preservative. In exp. 1 barley containing 30% moisture was treated with 0, 0.25, 0.5, 0.75 and 1.0% (wt/wt) sulfur dioxide and stored in 300-kg lots in wooden boxes from May to August. Grains treated with the two highest levels of chemical were well preserved. Sulfur dioxide treatment did not influence (P > 0.05) apparent digestibilities of dry matter (DM) or energy. In exp. 2, approximately 26 t of barley (22% moisture) were preserved with 1% sulfur dioxide. This material was in good condition when fed after 6 mo of storage; however, grain thiamin levels were below detectable limits and the sulfur content of the grain was increased from 0.27 to 0.68% (DM basis). Daily gains and gain: feed DM ratios were similar (P > 0.05) for 23 steers given dry barley and 24 steers given sulfur dioxide-treated barley during a 104-d feeding period when the grains were included in diets containing 90% concentrate with or without added thiamin. Dry matter intake of steers fed sulfur dioxide-treated grain tended (P < 0.10) to be reduced in the first 28 d of the trial (6.9 vs. 7.3 kg d−1) and final carcass backfat depths were reduced from 1.17 to 0.92 cm (P < 0.05) when treated grain was fed. In exp. 3 a barley/oat grain mixture (21% moisture) was treated with 1% sulfur dioxide in September 1983 and stored in a 22-t bin. The grain was well preserved when removed from the bin in November 1983. Sulfur dioxide treated-grain or addition of sodium bicarbonate to the diet had no influence (P > 0.05) on rate of gain, feed conversion or carcass weight when compared to dry grain when 16 heifers per treatment were fed 0.75 kg hay plus concentrate ad libitum. Carcass backfat depths were reduced (P < 0.05) from 1.16 to 0.92 cm when sulfur dioxide-treated grain was fed but were increased to 1.47 cm when sodium bicarbonate was added to the diet containing treated grain. In exp. 4 sodium metabisulfite preserved damp grain from October to January. In the last experiment the movement of sulfur dioxide through grain was examined. It was found that the chemical was ineffective when added at a single location at the bottom of a bin. It was concluded that sulfur dioxide and sodium metabisulfite are useful preservatives for high-moisture grain in small bins when the moisture content is below 30% and the ambient temperatures are cool. Key words: Sulfur dioxide, sodium metabisulfite, high-moisture grain, preservatives, cattle