THE PERFORMANCE AND THIAMIN STATUS OF PIGS FED SULFUR DIOXIDE TREATED HIGH-MOISTURE BARLEY

Abstract

High-moisture barley (HMB) was ensiled or treated with 1% (wt/wt) liquid sulfur dioxide (SO2). Forty-five weanling pigs were allocated to five dietary treatments for 28 d. Diets consisted of: (1) dry barley, diet mixed every 28 d; (2) ensiled HMB, diet mixed daily; (3) SO2-treated HMB, diet mixed every 28 d; (4) SO2-treated HMB, diet mixed daily; (5) SO2-treated HMB, diet mixed daily and supplemented with thiamin. All diets contained 47% barley on a dry matter (DM) basis. Pigs fed diets 2 and 4 continued on test to 85 kg; diets formulated after 28 d contained 75% barley (DM basis). Feed intake, growth rate and feed:gain ratio were not influenced (P < 0.05) by treatment during the 28-d initial trial. For pigs fed SO2-treated HMB to 85 kg, feed intake and average daily gain were reduced by 9.8 and 9.0%, respectively. SO2 treatment effectively preserved high-moisture barley for 18 d at 16 °C; however, 61% of the dietary thiamin was destroyed by 7 d after diet mixing. Pigs fed diet 4 were thiamin depleted at slaughter; with a 38.5% higher erythrocyte thamin pyrophosphate effect, an 83% incidence of cardiac hypertrophy and thiamin levels in meat reduced to 7.6% of that present in the meat of pigs fed untreated HMB. Destruction of dietary thiamin appears to have been the primary factor responsible for reduced animal performance. Reduced ration palatability and toxicological effects on the digestive tract due to 75% SO2 treated grain in the diet (DM basis) may have also contributed to the reduced performance of growing-finishing pigs. Key words: Sulfur dioxide, preservative, barley, pigs, thiamin