Effect of High Potency Growth Implants on Average Daily Gain of Grass-Fattened Steers

Abstract

Simple SummaryImproving efficiency in beef cattle production requires the adoption of technologies that are low cost but high in return. High potency growth-promoting implants (HGPs) are widely used under feedlot conditions but there are few reports of their use under grazing conditions. We conducted a trial to assess whether the use of high potency HGPs have advantages for grass-finished cattle. Our results were similar to those reported for feedlot cattle, showing that the quality of the pastures was good enough to take advantage of the HGP technology, generating a marginal income that justifies the use of technology under grazing conditions.AbstractHigh potency growth promoter implants (HGPs) are widely used under feedlot conditions but there are few reports under grazing conditions. The study’s goal was to assess the effect of HGPs on the average daily gain of steers fattened in pastures. A total of 57 crossbreed steers (Hereford × Angus)—initial body weight = 356.65 kg ± 5.04 (SEM)—were randomly allocated to one of three groups: Control without HGP (n = 19), Synovex group (n = 17), and Revalor group (n = 21). The fattening period was 67 days using paddocks of Lolium perenne L. and Trifolium repens L. Body weight was recorded three times in the period. The data were analyzed using an analysis of covariance with a level of significance of 5%. The average daily gain (ADG) (1.55 ± 0.07 and 1.48 ± 0.09 kg/d) and the total weight gain (103.4 ± 4.9 and 99.2 ± 5.8 kg) were similar for Revalor and Synovex, respectively (p > 0.05). Moreover, HGP groups showed higher ADG and total weight gain (p < 0.01) than the control group (ADG = 0.93 ± 0.08 kg/d and a total weight gain of 62.2 ± 5.2 kg). Final body weights were 527.8 ± 8.5 kg and 512.2 ± 9.9 kg for Revalor and Synovex, respectively; and 479.9 ± 10.1 kg for Control. In conclusion, grazing-finished steers showed better performance when high potency HGPs were used, improving the ADG and final live body weight, generating a marginal income that justifies the use of the technology under grazing conditions

Fattening performance and carcass traits of implanted and supplemented grassfed bulls

“…The unsuccessful attempts to improve the response of cattle with greater genetic potential indicate the need for ad hoc application of technological packages; particularly, when the ranchers in the area intend to fatten cattle at the same breeding operation and harvest them in packing houses authorized for carcass classification and grading, hoping for a better return on investment [17,29,30]. Synthetic anabolic implants, based on steroidal compounds such as trenbolone acetate + 17β-estradiol (ATB + E17) and non-steroidal, estrogenic compounds, such as Zeranol (a lactone of resorcylic acid, Ralgro®) constitute technological resources widely used to improve the response in productive performance and the lean: fat ratio in carcasses of castrated males (steers); especially under intensive fattening in North America [1,3,33]. On the contrary, few studies have evaluated the response of entire males (bulls or bullocks) to anabolics, yielding null or inconsistent results [12, 23 -25].…”

“…corresponds to a first dosis of Revalor ® at day 0, followed by a second dosis (72 mg) of Ralgro ® at day 90;3 A and B Venezuelan carcass categories correspond to the second -and third-quality, respectively;4 Carcasses of bulls younger than 30 mo. of age and (or) exhibiting an A physiological maturity are designated in the "Bullock" class, USDA Standard quality grade corresponds to the fourth quality, for bullock carcasses;5 USDA yield grades (YG) are rated numerically, namely 1, 2, 3, 4, and 5; a YG 1 carcass is expected to have the highest proportion (> 53.5 %) of boneless, closely-trimmed retail cuts, while a YG 5 carcass is expected to have the lowest proportion (< 44.3 %) of boneless, closely-trimmed retail cuts.…”

Efficacy of Hormonal Growth Promoter Implants on the Performance of Grazing Steers of Different Breeds in Southern Chile

“…A recent study carried out in a similar location to the current study compared the effects of two different implant treatments, Revalor ® and Synovex Plus ® (200 mg of tren-bolone acetate (TBA) and 28 mg of estradiol benzoate, respectively), in crossbreed steers (Hereford × Angus) under grazing conditions during spring. Implanted steers achieved a greater LWG, which was 39 kg more than the non-implanted steers (101 kg vs. 62 kg, respectively) over a 67-day period of grazing with no difference observed between the type of HGPI used [20]. This equated to an average daily gain (ADG) of 1.51 kg/d for the implanted steers compared to 0.93 kg/d for non-implanted steers.…”

“…In Chile, the dairy industry supplies approximately 80% of the animals for beef production, while the remainder are produced from beef cattle breeds [19]. Most are raised under grazing systems, with supplementation fed during the fattening phase (in winter and summer periods) in the form of conserved forages (as silage and/or hay) with or without a small amount of cereal grains [20]; which is mostly dependant on the geographical area in which the commercial farm is located [21].…”

“…The potential economic and environmental benefits and impacts of pasture-based beef systems compared to feedlot systems are widely understood [22]. However, despite the wide use of HGPIs in beef production in many countries, there is limited information available related to the growth performance of cattle implanted with HGPIs within grazing [20,23,24] and preserved forage [25,26] systems. The efficacy of HGPIs within these systems may differ from other systems (e.g., feedlots) due to differences in factors such as the environment and the feed type and provision, which may limit HGPI performance.…”