EFFECT OF BETA-GLUCAN, STARCH, AND FIBER CONTENT AND STEAM VS DRY ROLLING OF BARLEY-GRAIN ON ITS DEGRADABILITY AND UTILIZATION BY STEERS

Six lots of barley containing 3.5-4.8% beta-glucans, 56.5-65.6% starch and 5.7-9.7% acid detergent fibre (ADF) were processed by either dry or steam rolling and fed to two groups of 60 steers in a 6 X 2 X 2 factorial experiment designed to assess the effects of these components in commercially available barley on the performance of feedlot cattle. There were no detectable differences (P > 0.05) in daily gain (1.49-1.57 kg day-1), dry matter (DM) intake (9.09-9.77 kg day-1) or DM:gain ratio (5.85-6.35) between steers fed different lots of barley. However, significant (P < 0.04) correlations were detected between DM:gain ratios and barley starch and ADF content (R2 = 0.69 and R2 = 0.90, respectively). The percentage of DM which disappeared from the barley during a 24 h in sacco incubation was negatively related to the DM:gain ratio (R2 = 0.83; P = 0.01). Apparent digestibilities of beta-glucans, starch and ADF in the whole tract of steers were 98.6%, 98.1% and 29.1%, respectively. Steam rolling of barley had no influence (P > 0.1) on any aspect of steer performance. It was concluded that information on the ADF content of barley would be useful in predicting nutritive value and that steam rolling, relative to dry rolling, did not improve growth rate or feed efficiency of growing-finishing cattle.