Effect of concentrate feeder design on performance, animal behavior, and ruminal health in Holstein bulls fed high-concentrate diets

Abstract Text: A total of 240 Holstein bulls (121 ± 2.0 kg BW and 99 ± 1.0 d age), in a replicated factorial study, were randomly allocated in one of 6 pens and assigned to one of the 3 treatments according to the feeder design: conventional feeder with 4 feeding spaces (CF), conventional feeder with less concentrate capacity (CFL), and a single space feeder with lateral protections (SF) forming a chute (1.4 m x 0.8 m). Each pen had also 1 straw feeder, and 1 drinker. Concentrate intake was recorded daily, straw consumption weekly, and BW every 14 d. On days 7, 119-120, and 215-216 rumen fluid and blood samples were collected to determine rumen pH and VFA, and serum NEFA. Animal behavior was registered on day 1, 3, 5, 8, 14 and every 28 d by scan sampling. Animals were slaughtered after 221 d and HCW, rumen wall and liver lesions were recorded. Data were analyzed using a mixed-effects model with repeated measures. Bulls on CF tended (P = 0.07) to have greater ADG than CFL and SF bulls (1.54, 1.50 and 1.49 ± 0.017 kg/d, respectively). However, no differences among treatments were observed in concentrate intake (7.6 ± 0.16 kg/d), straw intake (0.8 ± 0.03 kg/d), FE (0.2 ± 0.01 kg/kg), HCW (247.2 ± 2.09 kg), dressing percentage (53.6 ± 0.23%), and rumen and liver lesions. Mean rumen pH was always above 5.6; at 7 and 215-216 d SF bulls had greater (P < 0.05) rumen pH compared with CF and CFL bulls. Acetate to propionate ratio was greater (P < 0.05) in SF compared with CFL and CF. At day 7 NEFA of SF was greater (P < 0.05) compared with CF and CFL, although at 119-120 d in SF bulls serum NEFA concentration was lesser (P < 0.01) than in CF and CFL bulls. Bulls on SF spent more time (P < 0.05) eating straw, exhibited lesser (P < 0.05) displacements at feeders and drinker, and expressed more oral behaviors (P < 0.05) than CF and CFL bulls. CFL bulls tended (P = 0.10) to perform more mounts than SF and CF. In conclusion, the different feeder designs evaluated did not affect overall performance, although some behavior traits differed among them. Serum NEFA concentrations at the beginning suggest that animals at the SF may have adaptation problems, and SF does not negatively affect rumen wall health and pH.

Keywords: beef, feeder, performance