36 Effects of Programmed Compensatory Gain on Feedlot Steer Behavior

Abstract

Abstract The objective was to determine effects of programmed compensatory gain on feedlot steer behavior after feeding. Simmental × Angus steers (n = 159; BW = 278 ± 49 kg) were blocked by BW, stratified by sire, and allotted to 10 pens. Each pen contained a 3.0 m-long bunk to allow 19 cm of linear bunk space per steer. Pens were randomly assigned to one of two treatments on d 0: control (CON) or programmed compensatory gain (PCG). To achieve programmed compensatory gain, previously growing animals were maintained at a constant BW by reducing the amount of feed offered by 3.29% daily for 10 consecutive d. This restricted feeding protocol was initiated on d 45. Thus, on d 54, PCG steers were consuming 72% of original dry matter intake (DMI) and subsequently returned to ad libitum intake to facilitate a period of compensatory gain. Feed intake for CON pens was managed using slick bunk management for the entire experiment. Behavior was observed before (d 37 and 44), during (d 47, 49, 51 and 54), and after programmed compensatory gain period (d 58 and 68) after morning and afternoon feedings (1 and 0.5 h, respectively). Data were analyzed using GLIMMIX procedure of SAS 9.4 using a beta distribution. Following morning feeding, a treatment by day interaction (P = 0.01) was observed for percentage of steers at the bunk as more PCG steers were at the bunk on d 47, 49, 52, 54, and 58 compared with CON steers. Following morning feeding, no treatment by day interactions (P > 0.14) were observed for steers waiting behind the bunk, standing, lying, or pushing. A greater percentage (P = 0.05) of PCG steers were waiting behind the bunk compared with CON following morning feeding (8.0 and 5.8%, respectively). A greater (P = 0.01) percentage of PCG steers were observed pushing compared with CON following morning feeding (12.5 and 7.3%, respectively). A greater (P < 0.01) percentage of PCG steers were standing compared with CON following morning feeding. Following afternoon feeding, no treatment by day interactions (P ≥ 0.13) were observed for steers at the bunk, waiting behind the bunk, standing, or pushing. A greater (P < 0.01) percentage of PCG steers were at the bunk and waiting behind the bunk compared with CON following afternoon feeding. A greater (P = 0.01) percentage of PCG steers were observed pushing compared with CON following afternoon feeding (10.7 and 4.2%, respectively). No effect (P ≥ 0.57) was observed for steers standing in the pen following afternoon feeding. Feed restriction associated with PCG only had minor impacts on steer behavior with observed increases in the percentage of steers at the bunk and waiting behind the bunk immediately after feeding.