Effect of castration and an anabolic implant on growth and serum hormones in cattle

Abstract

In the present study, a commercially available anabolic implant containing trenbolone acetate and oestradiol-17p was investigated in intact and castrated bulls. Measurements of growth rate, serum hormones and metabolites in both phenotypes, and testicular development and function in bulls, were obtained. The experimental objectives were realized in a 2 x 2 factorially designed experiment utilizing eight Angus-sired crossbred bulls and eight similar steers castrated at 7 months of age. Half of each group were implanted with 140 mg trenbolone acetate plus 28 mg oestradiol-17|3. Body weights were monitored every 7 days and plasma samples were obtained at 28-day intervals from 9 to 15 months of age. In the implanted groups, mean concentrations of plasma trenbolone and oestradiol-17p were 380 ng/1 and 31 ng/1, respectively. Trenbolone concentrations were undetectable in both non-implanted groups, and plasma oestradiol-17|3 was less than half that in implanted animals. While plasma GH concentrations were stratified according to implant treatment, they did not differ among the groups. Cortisol levels showed phenotype x implant interaction; implanted steers and non-implanted bulls had lower concentrations than non-implanted steers and implanted bulls. The implant resulted in no significant changes in gross testicular measures in the bulls but did affect the testosterone response to a GnRH challenge and basal plasma concentrations of testosterone were reduced. Plasma urea concentrations were reduced by the implant, but sex phenotype had no effect. Over the 175-day trial, implantation did not significantly improve the growth rate of bulls, except during the first third of the experiment. In contrast, implantation improved the growth rate of steers over the entire experiment, although implanted steers still grew more slowly than either implanted or non-implanted bulls. It can be concluded that the endocrine status of the young bull is set for a fast growth rate, making improvements via an anabolic implant marginal, except in the immature animal.

Effect of castration at 10 months of age on growth physiology and behavior of male feral beef cattle

“…In some production systems, growing calves are castrated to ease handling as well as to reduce sexual and aggressive behavior during the finishing phase. Castration alters growth rate and body composition in cattle due to a change in hormonal status (Henricks et al ). The description of underlying mechanisms mediating the hormonal status in growing bulls compared to castrated calves usually comes from American literature where anabolic implants are used (Lee et al ; Hunt et al ; Schoonmaker et al ).…”

The Effect of Improvac on Testosterone Level and Live Weight of Bulls

“…D.M. Henricks and others [2] relate such changes after castration with the corresponding changes in the restructuring of the hormonal status.…”

Interaction of growth hormone with androgen/estrogen on beef carcass characteristics, and chemical, physical and palatability properties of longissimus muscle of steers

“…simunarized five studies and reported that the combination between TBA and estrogen improved growth performance and carcass composition more efSciently than the compound used alone. A combination of implants do not alter growth hormone concentration when compared to control groups Henricks et al, 1988). Lee et al (1990) reported that combination implants of trenbolone acetate and estriadiol resiilted in a significantly (P > .05) increased serum concentration of IGF-1 levels when compared to nonimplanted controls.…”