PSV-5 - Impact of days on slats and locomotion score on growth performance of feedlot cattle

Abstract: The objective was to assess the impact of days on slats and locomotion score in a slatted, indoor feeding facility on steer growth performance. Fall-born, SimAngus steers (n = 138) were stratified and randomly assigned to treatments: long days on slats (LDOS) or average days on slats (ADOS). The LDOS steers were weaned at 80 days of age, and spent 262 days on slats. The ADOS steers were weaned at 206 days of age, and spent 192 days on slats. All steers received a Revalor-XS implant and were managed as a group thereafter. Concrete slats were covered with rubber matting, and pens had a minimum stocking density of 3.1 m² per steer. Steers were fed a common diet and individual daily feed intake was monitored using a Vytelle feed intake system. Dietary components consisted of corn silage, modified wet distillers grain, dry rolled corn, high moisture corn, and a ground corn-based supplement. Steers were fed lubabegron (36 mg/steer/day, Experior, Elanco, Greenfield, IN) for the final 50 days on feed. Prior to slaughter, steers were scored using the Step-Up Locomotion Scoring System (Zinpro). Steers with locomotion score 1 (LS1; n = 52) and locomotion score 2 (LS2; n = 55) were used in a post-hoc analysis in SAS 9.4 considering the effect of days on slats, locomotion score, and their interaction. There was an interaction observed (P = 0.02) for overall average daily gain; for LDOS steers, LS1 steers had a greater average daily gain than LS2 steers, while no effect was observed for ADOS steers. There was an interaction observed (P = 0.02) for overall dry matter intake (DMI); for LDOS steers, LS1 steers had a greater DMI than LS2 steers, but no effect was observed for ADOS steers. While no interaction was observed (P = 0.80) for DMI slope, LS1 steers had a greater (P = 0.03) slope than LS2 steers indicative of greater DMI over time. No interaction was observed (P = 0.99) for overall gain:feed; however, LS1 steers had a greater (P = 0.01) overall gain:feed. In conclusion, results indicated that LS1 steers had a greater DMI slope and overall gain:feed. However, an improved locomotion score only resulted in increased average daily gain and DMI when steers were fed for a longer period of time in a slatted-floor facility.