PSIII-8 Impact of SYNOVEX® ONE GRASS implantation during suckling on pre-weaning calf growth performance

Abstract

Abstract Historic data supports the use of pre-weaning implants to maximize beef calf weaning weight, but their use has declined over the recent decade. A total of 96 beef steers (initially 85.2 kg BW and > 45 d of age) were used in a 168-d study to evaluate the effects of Synovex C® implantation during suckling on pre-weaning calf growth performance. At initial processing, calves were individually weighed and allotted in a completely randomized design to one of two treatments: 1) not implanted (control) or 2) implanted with 150 mg of trenbolone acetate and 21 mg of estradiol benzoate (SYNOVEX® ONE GRASS, Zoetis, Kalamazoo, MI). All calves were weighed on d 0 (implantation), 83, 126 and 168 (weaning), with ADG calculated for each period. Data were analyzed using the GLIMMIX procedure of SAS (v9.4, Cary, NC). There were 48 replicates per treatment, with grazing location as a random effect. While there were no detected differences in BW during the initial phases (P > 0.10), implanted calves tended to have greater (P = 0.100) greater weaning weight than non-implanted calves (279 vs. 265 kg, respectively). Calves implanted with SYNOVEX® ONE GRASS had 0.8, 0.12, and 0.16 kg/d greater (P < 0.05) ADG than those that were not implanted in all three phases. This resulted in an average of 0.10 kg/d greater (P = 0.002) ADG in implanted calves overall compared to the control. In conclusion, this research showed significant increases in suckling calf ADG in implanted calves compared to their non-implanted counterparts, which led to a tendency for 14-kg greater weaning weights. Additional research is warranted to consider the post-weaning growth and impact of re-implanting, but this data reinforces previous literature that suckling calf implantation continues to be cost effective for cow-calf producers.