Effect of concentrate presentation form on concentrate wastage, eating pattern, and concentrate preference in Holstein bulls fed a finishing high-concentrate diet

Two experiments were conducted to evaluate the effects of concentrate presentation form on concentrate wastage, eating pattern, and concentrate preference in Holstein bulls fed a finishing high-concentrate diet. Additionally, the evolution of quality of this concentrate from the feed mill to the feeder was analyzed. In experiment 1, 112 Holstein bulls (272 ± 4.4 kg of body weight and 216 ± 1.0 days of age) were randomly distributed in 6 pens equipped with a computerized concentrate single-space feeder with lateral protections, a separated straw feeder, and a water bowl. Pens were assigned to either presentation forms of concentrate, pellets (PE) or crumbles (CR). The experiment followed a replicated Latin square design with 28-days periods. All animals received concentrate and straw ad libitum. Daily concentrate consumption and eating pattern, weekly straw consumption, and twice-weekly concentrate wastage were recorded for the last 14 days of each period. Animals were weighed every 14 days. For each concentrate manufacture, durability, hardness, density, and percentage of fines were determined at the feed mill, silo, feeder, and spillage collectors. In experiment 2, 6 Holstein bulls (404 ± 14.1 kg of BW and 254 ± 3.6 days of age) were enrolled to assess the concentrate preference for previous presentation forms of concentrate (PE or CR). The experiment consisted in a 7-days adaptation period and a 6-days free-choice period during which PE and CR were offered simultaneously. In Experiment 1, bulls fed PE had greater (P < 0.01) concentrate consumptions (7.18 vs. 6.87 ± 0.07 kg/d) and lesser (P < 0.01) wastage (0.06 vs. 0.11 ± 0.001 kg/d) compared with those fed CR. Bulls receiving CR spent more time at the feeder (P < 0.01) than bulls fed PE (44.4 vs. 40.7 ± 0.71 min/d). In Experiment 2, animals preferred numerically PE over CR (65.5 vs. 34.5 ± 4.89% to total concentrate consumption ratio). Lastly, as expected, concentrate quality based on durability was not a stable parameter, and it more progressively deteriorated (P < 0.01) from the mill to the feeder in CR than PE (96.7 vs. 87.1 ± 1.00%). The present study supports the hypothesis that a concentrate form like crumbles, which produces a great percentage of fines at the feeder, can increase concentrate wastage, and, also, it affects eating pattern, increasing the time spent at the feeder, and consequently decreases the concentrate intake. Lastly, animals prefer pellets over crumbles.