PSIX-14 - The Influence of Previous Plane of Nutrition on Feedlot Performance, Water Intake and Carcass Characteristics of Beef Steers

Abstract: The objective of this study was to evaluate how the background diet can affect the feedlot performance and carcass characteristics of finishing steers. Crossbred Angus steers (n = 24; 298.01 ± 10.17 kg) were fed either a low plane of nutrition (LP, n =12 ; triticale only, 91g/kg CP, 0.25Mcal/kg NEm, and 0.10Mcal/kg NEg) or adequate plane of nutrition (AP, n =12; 850g/kg alfalfa and 150g/kg beardless wheat, 126.2g/kg, 0.25Mcal/kg NEm, and 0.13 Mcal/kg NEg) during the background phase (85d). After this period, body weight (BW) of LP (362.81 kg ± 10.237) was less than the BW of AP (405.97kg ± 10.237). Animals were then transitioned to a finishing diet (800 g/kg whole corn and 200 g/kg alfalfa; 108 g/kg, 0.97Mcal/kg NEm, and 0.65 Mcal/kg NEg) and fed for 105d. Water intake (WI) and dry matter intake (DMI) were individually measured daily. Animals were then havested, and hot carcass weight (HCW) was obtained. Carcasses were chilled for 24 h, and qualified personnel measured longissimus dorsi area via direct grid reading between the 12th and 13th rib, USDA marbling score and yield grades. Differences amongst treatments were compared via orthogonal contrast using the GLIMMIX procedure of SAS (version 9.4). No differences were observed for WI, DMI, final BW and average daily gain among groups. Carcass characteristics such as HCW, yield grade, rib eye area, and dressing percentage were also similar between groups. On the other hand, animals previously on LP had a reducedr marbling score (421.11) than the AP treatment (493.21) (P = 0.0014). Therefore, even though the previous plane of nutrition did not affect intakes, performance, and carcass characteristics, the decreased amount of nutrients during the background decreased marbling of LP animals, which affects the final quality grade of the carcass as well as price per kg of carcass.