Impact of Adding Water to a Barley-Based Finishing Feedlot Diets on Cattle Feeding Behaviour and Ruminal Fermentation

Finishing feedlot diets have high grain and low forage (≤10% diet dry matter) contents, resulting in a dry, sortable diet. Competition among cattle pen-mates may result in varied consumed diets. The objective of this study was to evaluate the effects of water addition to finishing total mixed rations (TMR) as a strategy to bind ingredients together and reduce dietary sorting. Eight ruminally cannulated beef steers were used in a replicated 4×4 Latin square study. Four dietary treatments incorporated water at 0%, 10%, 20%, and 30% relative to the barley grain weight. Aggressively processed barley with 3.2% fines (±1.0%) detected treatment effects on dietary intake behaviour and rumen parameters. As water inclusion increased, both dry matter intake (DMI) and water intake linearly increased (P<0.01 and P=0.04, respectively). Sorting against small particles (P<0.01), mean ruminal pH (P<0.01), and maximum ruminal pH decreased linearly (P=0.02) with increased water inclusion. Moreover, increasing water addition linearly increased the time ruminal pH was below 5.5 (P=0.02). Total short-chain fatty acid and rumen ammonia-nitrogen concentrations remained unchanged (P≥0.46 and P≥0.22, respectively). Rumen lipopolysaccharide (LPS) concentration increased linearly with water inclusion (P<0.01). These data suggest that adding water to the TMR may enhance DMI, water intake and reduces dietary sorting. The ability of water to limit sorting was further confirmed by the longer duration of ruminal pH depression and increased concentrations of ruminal LPS. Ongoing research is needed to evaluate whether water addition affects average daily gain, feed efficiency, carcass merit, and pen variability for finishing beef cattle.

Presented at the 2024 Animal Nutrition Conference of Canada. For information on the next edition, click here.