Chemically Treated Oat Hulls in Diets for Dairy Heifers and Wethers: Effects on Intake and Digestion

Abstract Two experiments were conducted to determine the effects of inclusion of alkaline hydrogen peroxide-treated oat hulls in diets on feed intake and nutrient digestion by wethers and growing heifers. In a pilot study with six wethers, we compared diets with untreated versus treated oat hulls containing 60% roughage and 40% concentrate (DM basis). Holstein heifers (n = 12) were used in three replications of a 4 x 4 Latin square design to compare diets containing 10% concentrate and 0 (control), 20.4 (low), 40.6 (medium), and 60.5% (high) treated oat hulls with the remainder being alfalfa haylage DM basis). Digestibilities of DM, NDF, and ADF were increased by at least 12 percentage units, and digestible nutrient intakes increased 73 g/d for wethers fed the treated oat hull diet versus the untreated diet. Intakes of DM by heifers were 8.9, 9.4, 9.6, and 9.2 kg/d for the control, low, medium, and high treated oat hull diets, respectively. Apparent digestibilities of DM, OM, NDF, and ADF were increased by 7.1, 6.7, 24.5, and 10.5 percentage units, respectively, for the high oat hull versus control diet. Gains in BW ranged from .77 kg/d for heifers fed the high diet to 1.1 kg/d for those fed the medium diet. Heifers fed larger amounts of treated oat hulls had lower ruminal pH and ammonia N concentrations, higher molar percentage acetate, and greater acetate:propionate ratios than controls. Heifers fed diets containing treated oat hulls had higher digestible DM and fiber intakes than controls. Treated oat hulls have a place in diets of growing ruminants.