Corn and Barley Mixtures in Finishing Steer Diets Containing Potato Process Residue

Two finishing trials were conducted with steers (Bos taurus; 781 lb) to evaluate the feeding value of Northwest grown corn (Zea mays L; differing in grain processing method) and barley (Hordeum vulgare L.) in diets containing potato (Solarium tuberosum L.) process residue. Steers were fed once daily in pens of nine head each with three pens per dietary treatment. Diets were formulated to contain 65% grain, 8% corn silage, 8% alfalfa hay, 14% potato process residue, and 5% supplement on a dry matter (DM) basis. In Trial 1, steam-rolled grain treatments were: 100% corn; 67% corn, 33% barley; 33% corn, 67% barley; and 100% barley as a percentage of the dietary grain DM. In Trial 2, grain treatments were: 100% high moisture corn (HMC); 67% HMC, 33% barley; 33% HMC, 67% barley; 100% barley; 50% barley, 50% dry rolled corn (50:50); 100% dry rolled corn (DC); and 100% steam-rolled corn as a percentage of the dietary grain DM. In Trial 1, steer average daily gain (ADG), final weight, and dry matter intake (DMI) were affected cubically as barley replaced com. Carcass parameters of hot carcass weight, marbling score, and quality grade decreased linearly (P < 0.05); and backfat thickness tended to decrease linearly (P < 0.10) as barley replaced corn. In Trial 2, steer ADG (3.7 lb/d) was not affected by treatment but DMI was affected cubically (P < 0.05) and feed to gain ratio decreased quadratically as barley replaced HMC. Marbling score decreased linearly (P < 0.05) as barley replaced HMC or DC. Quality grade tended to decrease linearly (P < 0.10) as barley replaced DC. These data indicate variability in feeding value of Northwest grown corn (differing in grain processing method) relative to barley and primarily positive associative effects of mixtures of corn and barley in finishing diets containing potato process residue.