Effects of graded levels of potato by-products in barley- and corn-based beef feedlot diets: I. Feedlot performance, carcass traits, meat composition, and appearance

To measure effects of diet on feedlot performance, carcass characteristics, and beef appearance, 144 crossbred beef steers (333 +/- .44 kg) were allot ted within weight block (3) to a randomized complete block design with a 2 x 3 factorial arrangement of dietary treatments. Main effects were grain (b arley or corn) and level of potato by-product (PB) (0, 10, or 20% of diet D M). Steers were fed diets containing 83% concentrate (grain plus PB), 10% s upplement, and 7% alfalfa on a DM basis for an average of 130 d. Level of P B quadratically affected (P <.10) DM intake and gain such that steers fed 1 0% PB ate more and gained faster. Corn-fed steers were more (P <.05) effici ent (5.8 vs 6.3 kg DM/kg gain) and had more (P <.05) kidney, pelvic, and he art fat (2.2 vs 2.0%) than barley-fed steers. A grain x PB interaction was detected (P <.10) for marbling score, which was minimized in steers fed bar ley diets (small 0) but maximized in those fed corn diets (small 30) at 10% PB. Diet did not affect beef firmness or beef color score. Barley-fed beef had whiter fat (P <.05) than corn-fed beef (2.6 vs 2.9 on a 1 to 7 scale); however, fat luster score was not affected by diet. Small differences were noted in fatty acid profile, purge, drip loss, and muscle pH. No differenc es were noted in color measurements due to dietary treatment over 7 d of re tail shelf life. Overall, differences were small and probably not biologica lly important. These results indicate that these diets had minimal effects on beef appearance and carcass characteristics, meat composition, and water retention properties.