PSIX-41 The potential for different supplement sources to reduce frothy legume bloat based on in vitro degradation characteristics

Previous research has shown that supplementation of corn silage or grass hay can reduce the incidence of frothy legume bloat in cattle. However, forage-based supplements may not be the most feasible supplements due to the infrastructure required for harvest, storage, and feeding. The objective of this experiment was to evaluate the effects of different supplement sources, commonly available in the upper Midwest, on in vitro digestion kinetics and extent of digestion of alfalfa-based diets. Two ruminally-cannulated steers (928.1±25.5 kg BW) were fed alfalfa hay at 2.0% of BW and served as donors of rumen fluid. Treatments were early-bud alfalfa (CON) or a combination (DM basis) of 80% early-bud alfalfa with 20% of corn silage (CS), brome grass hay (BGH), soybean hulls (SBH), beet pulp (BP), corn grain (CORN), dried distillers’ grains with solubles (DDGS), or wheat middlings (MIDD). Tubes were incubated for 0, 3, 6, 9, 12, 15, 18, 21, 24, 48, or 72-h and assessed for rate and extent of digestion. Samples were run in duplicate and replicated over 4 days. Data were analyzed using the GLM procedure of SAS. Measurements reported are from the 48-h incubation. Apparent DM and OM digestibility was increased (P < 0.001) with SBH, BP, CORN, and MIDD and decreased with BGH. True DM digestibility was increased (P < 0.001) with SBH, BP, CORN, and DDGS and decreased with BGH. All treatments besides BGH and MIDD reduced (P < 0.001) NDF digestibility in comparison to CON. All treatments besides BP reduced (P < 0.001) the absolute initial rate (3-h) of apparent DM digestion, and SBH had the lowest rate. These data show that SBH increases the extent of digestion, while reducing the initial rate of degradation, suggesting that SBH has potential to reduce the incidence of frothy legume bloat as an alternative to corn silage or grass hay.