Effect of feeding protocol on intake by Angus bulls

Individual intakes are required to evaluate rate and efficiency of gain in young bulls. The objectives were to confirm use of alkanes as acceptable markers to calculate DMI of corn silage-based diets and to assess changes in DMI by Angus bulls (288 to 402 kg of BW) in response to individual feeding or group feeding. An 80:20 corn silage:supplement TMR was offered to 12 Angus bulls in each of 2 yr. The bulls were housed together and fed individually (period 1), group fed in a bunk (period 2), then again fed individually (period 3). Periods lasted 21 d. In addition to the TMR, each bull consumed 0.908 g/d of 50:50 corn grain:soybean hulls. Feed intake was recorded daily. Fecal grab samples were collected during the last 5 d of each period to calculate TMR DMI from feed and fecal content of hentriacontane and dotriacontane. Measured and calculated TMR DMI did not differ (P < 0.16) in period 3. Although average daily TMR DMI of the bulls did not change from period 2 (2.58 kg of DM/kg of BW, calculated with markers) to 3 (2.42 kg of DM/kg of BW, P < 0.11), 21 of the 24 bulls gained or lost DMI rank by 2 or more positions among pen mates as the method of feeding changed among periods. Changes in DMI for a given bull ranged from 0.15 to 3.2 kg/d. Feeding method may not affect DMI of the top-ranked or bottom-ranked bulls, but intermediate bulls may change rank in response to individual or bunk feeding.