Impact of adding water to a barley-based finishing feedlot diet on feed sorting behaviour and ruminal fermentation for growing beef steers

This study evaluated the effects of adding water to a barley-based feedlot diet on feed intake, feed sorting, ruminal fermentation, and apparent total tract digestibility. Eight ruminally cannulated Hereford crossbred steers were used in a replicated 4 × 4 Latin square design with 4 dietary treatments. Steers received a common diet with aggressively processed dry-rolled barley grain to create a sortable diet. Water was added to the total mixed ration, equating to 0% (CON), 10% (10W), 20% (20W), and 30% (30W) of the barley grain weight. Data were analyzed using the MIXED procedure of SAS with linear and quadratic contrasts. Adding water linearly increased dry matter intake (DMI; P < 0.01) and water intake ( P = 0.04). As water inclusion increased, the sorting index for particles on the pan approached 100% (linear, P < 0.01) indicating greater fine particle consumption. Mean ( P < 0.01) and maximum ruminal pH linearly ( P = 0.02) decreased, while the duration that pH was <5.5 ( P = 0.02) and the concentration of lipopolysaccharide in ruminal fluid increased linearly as water inclusion increased ( P < 0.01). These data suggest that adding water to a barley-based feedlot diet reduces dietary sorting and increases DMI but elevates the risk of ruminal acidosis when using aggressively processed barley grain.