Effects of the Programmed Nutrition Beef Program on feedlot performance and carcass characteristics

The objective of this study was to examine the effects of alternative finishing strategies on feedlot performance and carcass characteristics. Beef steers (64 pens; 8 steers/pen) were allocated to a randomized complete block design with a 2 x 2 factorial treatment arrangement. Factor 1 consisted of diet, with cattle fed a conventional (CON) diet or a diet consisting of Programmed Nutrition Beef Program (PN) supplements. The PN treatment included Programmed Nutrition Beef Receiver fed from d 1 through 20 of feeding and Programmed Nutrition Beef Finisher fed from d 21 to harvest. Factor 2 evaluated the presence (EGP+) or absence (EGP-) of exogenous growth promotants (ExGP) in the production system. Steers in the EGP+ treatments were initially implanted with Component E-S, reimplanted with Component TE-IS, and fed 400 mg.animal(-1).d(-1) of ractopamine hydrochloride for the final 28 d before harvest. Steers were harvested on d 175, and strip loins were removed from 2 carcasses selected at random from each pen for transport to Kansas State University. One 1.27-cm-thick steak was removed from the anterior face for proximate and long-chain fatty acid analysis. There were no diet x ExGP interactions (P > 0.10) for feedlot performance except for DMI (P = 0.02). Steers in the PN/EGP+ treatment consumed more feed than all other treatments (P < 0.05). Both diet and ExGP affected DMI (P < 0.05), with PN and EGP+ steers consuming more feed than their contemporaries. Gain:feed and ADG were unaffected (P > 0.10) by diet, but ExGP improved these measures (P < 0.01). There were no diet x ExGP interactions for carcass characteristics except KPH fat and percentages of yield grade 3 and 4 carcasses (P < 0.05). Diet affected total incidence of liver abscesses because PN steers had a greater (P = 0.05) incidence of liver abscesses than steers in the CON treatment. Diet did not affect the other carcass characteristics (P > 0.10). Use of ExGP increased (P < 0.05) HCW, LM area, and 12th-rib fat but did not affect (P > 0.10) marbling score. Using ExGP reduced the percentage carcasses grading Premium Choice (P < 0.05). No diet x ExGP interactions or diet effects were detected for long-chain fatty acid profiles (P > 0.10). Use of ExGP increased (P < 0.05) the ratio of saturated:unsaturated fatty acids. In summary, the alternative feeding strategy presented in this study produced similar feedlot performance and carcass characteristics compared with a conventional feedlot system.