Trenbolone acetate/estradiol combinations in feedlot steers: dose-response and implant carrier effects2

Abstract

Two experiments were conducted at three locations to determine the correct dosage and carrier for trenbolone acetate (TBA) and estradiol (E2) implants in feedlot steers. In the dose-response experiment, 1,296 steers were allotted to six implant treatments (48 pens per location): control, 140 mg of TBA (140/0), 30 mg of E2 (0/30), 20 mg of TBA + 4 mg of E2(20/4), 80 mg of TBA + 16 mg of E2(80/16), and 140 mg of TBA + 28 mg of E2 (140/28). In the carrier experiment, 575 steers were allotted to five implant treatments (25 pens per location): control, 140 mg of TBA + 28 mg of E2 in lactose (140/28-LA), 140 mg of TBA + 28 mg of E2 in cholesterol (140/28-CH), 140 mg of TBA + 20 mg of E2 in LA (140/20-LA), and 200 mg of progesterone + 20 mg of E2 benzoate (SS, reimplanted). In both experiments steers were fed a finishing diet for 140 to 168 d. In the dose-response experiment, response to TBA alone (140/0) did not differ from control (P greater than .2). Estradiol alone (0/30) improved ADG by 7% (P less than .01) and tended to improve feed efficiency over control (3%, P = .17). The highest dosage (140/28) improved ADG by 18% (P less than .001) and feed efficiency by 10% (P less than .001) over control and 10% (P less than .001) and 7% (P less than .01) over E2 alone, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a combined trenbolone acetate and estradiol implant on feedlot performance, carcass characteristics, and carcass composition of feedlot steers.

“…Our findings for LMA on d 115 were similar to other reports that have shown increased LMA in steers implanted with a combined implant containing 140 mg of TBA and 28 mg of E 2 (Eversole et al, 1989;Bartle et al, 1992). In contrast, Perry et al (1991) found that TBA+E 2 (140/28) had no effect on LMA in steers from various breed groups.…”

“…However, the TBA+E 2 -implanted steers always maintained greater gains than nonimplanted steers regardless of the stage of the feeding period. Administration of separate TBA and E 2 implants at various doses and combining TBA+E 2 at a higher dose (140/28) have resulted in increases of 18 to 25% in ADG and an average improvement in feed efficiency of 10 to 18% in implanted steers relative to nonimplanted steers (Schanbacher, 1984;Eversole et al, 1989;Anderson, 1991;Perry et al, 1991;Bartle et al, 1992). Although we cannot compare our results directly to previous reports with different combinations of TBA and E 2 , our survey of the literature suggests that expected differences in performance are similar regardless of whether steroids are delivered separately or from a combined implant.…”

“…Since 1992, cattle producers in the United States have had the option of using a single implant that contains both an androgen (trenbolone acetate; TBA) and an estrogen (estradiol; E 2 ) source. Earlier research indicated that a combined TBA+E 2 implant increased growth rate and improved feed efficiency approxi-mately 20 and 15%, respectively, during a typical feeding period compared with nonimplanted steers (Schanbacher, 1984;Bartle et al, 1992).…”

The Effect of Delaying Initial Feedlot Implant on Body Weight, Average Daily Gain, and Carcass Characteristics of Calf-Fed Steers

“…The major focus of this study was to determine the impact of delaying the initial feedlot implant on QG in calf-fed steers. When evaluating previous research, studies have shown that the use of implants has little or no effect on MS or QG (Bartle et al, 1992;Gerken et al, 1995), whereas other studies have shown a substantial reduction in MS and QG (Foutz et al, 1990;Senn and Wagner, 1994). In previous work using delayed implant programs in calves fed for 212 d, Samber et al (1996) demonstrated no difference in MS or QG from 2 delayed implant programs compared with control nonimplanted cattle; however, MS and QG were both decreased in calves implanted with 3 successive implants.…”

Trenbolone enhances myogenic differentiation by enhancing β-catenin signaling in muscle-derived stem cells of cattle

“…Trenbolone acetate is a synthetic analog of testosterone which is widely used in the US and Canada (8). Implanted trenbolone in steers enhances animal growth performance and increases muscle mass (9-12). To date, however, the underlying mechanisms for the biological effect of testosterone on muscle growth are not very clear.…”