Date of this Version
Bittner, C. J. 2016. Effects of feed additives and body weight on growth performance and carcass characteristics of beef finishing cattle. Ph.D. Dissertation. Univ. of Nebraska, Lincoln
A pooled-analysis of feedlot pens examined the effects of steer age (calf-fed, short yearling, long yearling) and initial body weight on feedlot growth performance. Feed efficiency decreased linearly as initial body weight increased for all age groups of steers.
Three feedlot experiments evaluated the effects of NEXT ENHANCE (EO) and monensin/tylosin (MT) on growth performance and carcass characteristics in beef finishing diets. In Exp. 1, there were no MT x EO interactions for finishing performance and carcass characteristics. Feeding MT resulted in a 3.9% improvement in G:F compared to steers fed no MT. Feed efficiency was not different between steers fed EO and those not fed EO. In Exp. 2, EO dose (0, 75, 150, 225, or 300 mg/steer daily of EO) was evaluated. Increasing EO dose linearly decreased DMI, but ADG was not different among treatments. Feed efficiency linearly increased as EO dose increased. Feeding EO at 225 and 300 mg/steer daily improved G:F 4.4 and 3.8% compared to steers fed 0 EO. In Exp. 3, concentration of EO (0, 16.5, 33.1, or 49.6 mg/kg of EO) was evaluated. Concentration of EO had no effect on DMI, ADG, or G:F.
Two experiments evaluated the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of finishing steers. In Exp. 1, RAC dose (0 or 200 mg/steer daily) and RAC duration (28 or 42 d prior to harvest) were evaluated. Hot carcass weight was 6.0 kg heavier for steers fed 200 mg/steer daily of RAC for 28 d compared with steers fed 0 RAC for 28 d. Feeding 200 mg/steer daily of RAC increased HCW 4.0 kg over steers fed 0 RAC for 42 d. In Exp. 2, RAC dose (0, 300, and 400 mg/steer daily) and RAC duration (14, 28, or 42 d) were evaluated. Feeding 300 mg/steer daily of RAC for 28 and 42 d increased HCW by 5.1 and 7.6 kg compared to steers fed 0 RAC. Additionally, feeding 400 mg/steer daily of RAC for 28 or 42 d increased HCW by 8.9 and 9.4 kg compared to steers fed 0 RAC.