Journal Article

39 Effects of Growth Promoting Implants at Branding in Suckling Steers Prior to Weaning

Lester, T D, Kegley, E B, Powell, J G, Palmer, E A, Gragg, W, Ball, J J

2018

Overview

Abstract Crossbred beef steers (n = 106; BW = 96 ± 3.9 kg; Age = 74 ± 2.0 d) were blocked by parity of dam (≤ 2 or > 2 parities), stratified by BW, age, and sire, and assigned randomly to 1 of 3 implant treatments on d 0: 1) Ralgro; 36 mg zeranol, 2) Component E-C; 100 mg progesterone and 10 mg estradiol with 29 mg tylosin, 3) Control; received no growth promoting implant. Body weights were recorded on d -7, 0 (branding), 57, 98, and 156 (weaning). Sera was harvested from a subset of calves (n = 48) for the analysis of blood urea nitrogen (BUN) and NEFA on d 0, 57, 98, and 156. Data were analyzed using the MIXED procedures of SAS with calf serving as the experimental unit for all dependent variables and analysis of BUN and NEFA utilized a repeated measures statement with main effects of treatment, day, and the interaction of treatment × day with α = 0.05. Day 0 BW were not different (P = 0.90) between treatments. Interim BW on d 57 and 98 were not affected (P ≥ 0.53) by growth promoting implants. Weaning BW were similar (P = 0.19) between all treatments; however, there was a tendency (P = 0.08) for greater weaning weights in implanted calves (239 kg) compared to non-implanted calves (225 kg). Average daily gain from d 0 to 57 was not affected (P = 0.59) by the use of growth promoting implants. Implanted steers had greater (0.91 vs. 0.79 kg/d; P = 0.04) ADG from d 57 to 98; however, type of implant was not different (P = 0.84). Average daily gain from d 98 to 156 was greater (P = 0.05) in Ralgro (1.25 kg/d) and Component E-C (1.21 kg/d) compared to Control (1.12 kg/d). Overall ADG from d 0 to 156 (weaning) was greater (P = 0.03) in Ralgro (0.91 kg/d) and Component E-C (0.90 kg/d) compared to Control (0.82 kg/d). There was no interaction (P = 0.86) of treatment × day, nor a main effect (P = 0.54) of treatment for NEFA concentrations. A treatment × day interaction was not detected (P = 0.27) for BUN concentrations; however, BUN were greater (P = 0.01; treatment main effect) in Control compared to Component E-C whereas Ralgro was intermediate. Implantation of male calves at branding, regardless of implant type, increased growth performance prior to weaning.

• Publisher: Oxford University Press