PS4-6. Impact of LYSOFORTE® Extend on Feedlot Cattle Performance and Carcass Characteristics.

Abstract Four hundred and eighty crossbred Angus steers were ranked by body weight (BW) and randomly assigned to one of two experiments. Experiment 1 (n = 240 steers) treatments consisted of: 1) Control diet: No added fat, no added LYSOFORTE® Extend (LFE; Kemin Industries, Inc.) and 2) Control diet + LFE (4.25 g of LFE·head-1·day-1). Experiment 2 (n = 240 steers) treatments consisted of: 1) Control diet + 1.75% added tallow and no LFE and 2) Control diet + 1.75% added tallow and LFE (6.0 g of LFE head-1·day-1). A steam-flaked corn-based diet with the appropriate treatments was delivered daily to provide cattle with ad libitum access to feed over a 24-h period. For both experiments, steers were housed in feedlot pens containing 15 steers per pen with 8 replicate pens per treatment per experiment. Body weights and feed refusals were collected every 28 d throughout both experiments. After reaching a finished BW of approximately 695 kg (approximately 150 days on feed), equal numbers of pens per treatment for each experiment were transported to a USDA-inspected commercial abattoir, slaughtered, and carcass data collected. Experiment 1: Treatment had no impact on any live animal performance or carcass characteristic response variables measured. Experiment 2: Initial and final BW and feed efficiency were similar across treatments. Overall, ADG was greater (P < 0.05) and DM intake tended (P < 0.06) to be greater in steers receiving LFE. Hot carcass weights, dressing percentage, longissimus muscle area, and liver scores were similar between treatments. Steers receiving LFE had greater (P < 0.04) marbling scores compared to Controls. Under the conditions of these experiments, LFE inclusion at 4.25 g head-1·day-1 had no impact on live animal performance or carcass characteristics when tallow was not added to the diet. However, steers receiving LFE at 6.0 g head-1·day-1with tallow added to the diet giving a total dietary fat percentage of 6.24 had greater overall ADG and marbling scores compared to Controls.