INFLUENCE OF GRAIN TYPE AND OIL CONCENTRATION OF DRIED CORN DISTILLERS GRAIN WITH SOLUBLES ON RUMINAL FERMENTATION AND IN VITRO GAS PRODUCTION IN CATTLE FED HIGH-CONCENTRATE DIETS

To determine the effects of grain type (rolled-corn vs. rolled-barley) and dried corn distillers' grains with solubles (DDGS) oil concentration (low = 4.5% vs. moderate = 7.9%) on ruminal pH, ammonia (NH3) and volatile fatty acid (VFA) concentrations, in vitro enteric methane (CH4) and carbon dioxide (CO2) production, and digestive enzyme activity, eight ruminally cannulated Holstein steers (715 +/- 61.4 kg) were used in a 4 x 8 Latin rectangle with a 2 x 2 factorial arrangement of treatments. Diets were offered for ad libitum intake. Experimental periods were 24 d with 7 d of diet adaptation, 7 d of sample collection, and a 10 d transition between periods. No differences were observed for ruminal NH3, total VFA concentration, pH, or in vitro concentration of CH4 or CO2 after 24 h of incubation among treatments. The lag time for in vitro gas production and degradation was greater (P = 0.03) from steers fed diets containing rolled-corn than rolled-barley. There were grain type x DDGS interactions (P <= 0.02) observed for a-amylase and trypsin activity (U L-1 ruminal fluid). Maltase activity (U L-1 ruminal fluid) was greater (P <= 0.01) in steers fed diets containing rolled-corn than rolled-barley and in steers fed diets containing low- compared with moderate-oil DDGS. These results indicate that, although ruminal enzyme activity was influenced, feeding different grain types (rolled-corn vs. rolled-barley) or DDGS with differing oil concentration (moderate vs. low) did not negatively influence ruminal fermentation or in vitro CH4 production.