Effects of trenbolone acetate on carcass characteristics and serum testosterone and cortisol concentrations in bulls and steers on different management and implant schemes.

Abstract

The objective of this study was to determine the effects of different implanting schemes on serum testosterone and cortisol concentrations, and carcass traits of bulls and steers implanted with trenbolone acetate (TBA) and zeranol (Z). Twenty Polled Hereford bulls were randomly assigned to one of three treatments after birth. Five calves served as nonimplanted control bulls (NIB). Nine bulls were implanted (IB) with 140 mg of TBA and 36 mg of Z at about 1 mo of age and reimplanted with both compounds 10 wk later. When IB calves were about 21 wk of age, the TBA implant was removed and calves were reimplanted with Z every 10 wk until slaughter. Six calves were castrated at 3 wk of age and implanted (IS) with TBA and Z every 10 wk until slaughter. Blood samples from each animal were obtained at 14-d intervals beginning at 14 wk of age and serum cortisol (C) and testosterone (T) concentrations were determined. The NIB had higher C levels than IB or IS (P less than .05) during the preweaning period. During the finishing period, there were no differences in C concentrations between NIB and IB; however, IS had lower levels (P less than .05) than both bull treatments. Serum T concentrations began to increase about 12 wk later (42 vs 30 wk, respectively) in IB compared with NIB. Testicular size was smaller (P less than .05) in IB than in NIB. No differences (P greater than .05) were observed in carcass characteristics. Taste-panel scores were not different among treatments. In conclusion, implanting schemes using TBA and Z lowered serum levels of C and delayed puberty in bulls; however, they did not alter carcass characteristics or eating quality.

Testis function and feedlot performance of bulls actively immunized against gonadotropin-releasing hormone: effect of implants containing progesterone and estradiol benzoate

“…The inhibition of testicular growth in prepubertal bulls with estradiol or zeranol implants is accompanied by reduction in testicular function as well. Thus, T secretion is reduced (Calkins et al, 1986;Jones et al, 1991) and spermatogenesis (Ballachey et al, 1986;Godfrey et al, 1989) is attenuated in implanted cattle. The diameter of the seminiferous tubules is also reduced in bulls implanted with zeranol (Ballachey et al, 1986).…”

Effects of ractopamine and trenbolone acetate implants with or without estradiol on growth performance, carcass characteristics, adipogenic enzyme activity, and blood metabolites in feedlot steers and heifers1,2,3

“…No changes (P > 0.10) in cortisol were associated with feeding RAC. Others have also observed a decrease in circulating concentrations of serum cortisol associated with the use of E17B or TBA implants (Jones et al, 1991;Hayden et al, 1992). In human medicine, glucocorticoids inhibit the physiological secretion of GH (Solomon and Bouloux, 2006) and decrease IGF-1 production at target organs (Schakman et al, 2008).…”

Testosterone, dihydrotestosterone, trenbolone acetate, and zeranol alter the synthesis of cortisol in bovine adrenocortical cells

“…Higher levels of testosterone and decreased cortisol concentrations result in increased rate of gain, feed efficiency, and lean muscle tissue production (Henricks et al, 1984;Sillence et al, 1987). A reduction of serum cortisol has been observed in animals implanted with both androgenic and estrogenic compounds, suggesting that part of the response to implants may be a decline in the catabolic action of cortisol, which increases protein accretion (Henricks et al, 1984;Sillence et al, 1987;Jones et al, 1991).…”