A new oat cultivar, CDC SO-I, with a low lignin hull and high oil groat was evaluated in backgrounding diets for steer calves, with an emphasis on the requirement for processing. Average daily gain was not different (P > 0.05) between calves fed rolled barley, rolled oat, or whole oat diets. Dry matter intake of cattle fed the rolled oat diet was greater (P = 0.04) than that of cattle fed the rolled barley or whole oat diets. Feed:gain was not affected (P = 0.13) by treatment. Results indicate the CDC SO-I oat does not require processing (i.e., rolling), and can replace barley in backgrounding diets with no negative effect on animal performance. Key words: Oat, growing cattle, feedlot, high oil, low lignin

This study was conducted to evaluate the effects of feeding a processed barley/canola meal pellet on feedlot performance and carcass quality of feedlot steers. Cross-bred steers (N = 350) weighing 285 ± 22kg were assigned to 1 of 12 pens and fed either pelleted (PB) or rolled (RB) barley as the concentrate. During backgrounding, cattle were fed a diet that contained 41% PB or RB based-concentrate (DM basis), which consisted of 85% barley and 15% canola meal. During finishing the diet contained 86% concentrate (DM basis), which consisted of 94% pelleted or rolled barley and 6% canola meal. Data collection included daily pen feed intake, individual body weights, ultrasound backfat (USBF) and longissimus dorsi (USLD) area measurements. Carcass data included weight, dressing percentage, marbling and liver abscess scores. Carcass fat, lean and bone percentage, fat color, and l. dorsi intramuscular fat content and fatty acid profile were determined on eight-bone rib samples from 20 randomly selected steers from each treatment. Steers fed the PB had similar ADG during backgrounding (1.29 vs. 1.23 kg d-1; P = 0.30); however, during finishing (1.80 vs. 2.00 kg d-1; P < 0.01) and for the total trial (1.60 vs. 1.70 kg d-1; P < 0.01), daily gains were greater for cattle fed RB. As a result, cattle fed PB were on feed for 10 d longer (P = 0.01) than RB fed cattle. DMI was lower (P < 0.01) for cattle fed PB throughout the trial. Feed conversion (kg feed:kg gain) was superior for the group fed the PB during finishing (6.03 vs. 6.21; P = 0.01) and the total trial (6.27 vs. 6.64; P < 0.01). Both diets produced similar carcasses, but inter-muscular fat percentage was higher (P = 0.03) for the RB group (60.0 vs. 57.4%). Minor differences in fatty acid profile were noted with PB fed steers having higher (P < 0.01) levels of C17:0, C18:3n-3 and C20:4n-6. Results from this study indicate that PB can be used effectively in growing programs, however, further research is required to better manage feeding of PB products to avoid DMI reductions most likely due to sub-acute rumen acidosis. Key words: Cattle, processed barley, performance, carcass quality and composition

A series of three completely randomized design trials were conducted to compare the effects of a limit-fed high-grain diet relative with that of an ad libitum-fed high-forage diet on performance of growing cattle with similar total energy intakes. In trial 1, the ad libitum-fed high-forage diet was formulated to 1.58 and 0.98 Mcal NEm and NEg kg-1 DM. The high-grain diet was formulated to 1.91 Mcal NEm and 1.23 Mcal NEg kg-1 DM. Projected liveweight gains (1.22 kg d-1) and the amount of DM provided to the limit-fed high-grain cattle were based on the NEm and NEg equations for liveweight gain of large-frame steers (NRC 1984). A similar feeding regime was employed for trials 2 and 3; however, it was necessary to reduce energy intake equally after 30 d on feed to control weight gains. In trial 1, the limit-fed high-grain cattle had similar (P > 0.05) ADG and lower (P < 0.05) DMI than the ad libitum-fed high-forage cattle, leading to a 15.4% improvement (P < 0.05) in feed efficiency. Feed efficiency was improved (P < 0.05) by 16.9% in trial 2 and by 21.2% in trial 3 for the limit-fed high-grain cattle, primarily as a result of reduced (P < 0.05) DM intake and similar (P > 0.05) daily gains. Back fat accretion rates were greater (P < 0.05) in the limit-fed high-grain cattle, indicating differences in energy partitioning. The incidence of severe liver abscesses was greater (P < 0.05) for the limit-fed high-grain cattle in trial 2. These results indicate that limit feeding a high-grain diet to backgrounding cattle can be employed to target specific rates of gain and improve feed efficiency although managing acidosis to prevent liver abscesses may be an issue. Key words: Cattle, limit feeding, feed efficiency, liver abscesses