Influence of a hormonal preparation containing glucocorticoids (dexamethasone esters), progestagen (chlormadinone acetate) and oestrogen (ethinyl oestradiol) on testosterone, insulin-like growth factor-1 (IGF-1), IGF-binding proteins and spermatogenic cells in finishing bulls

Abstract

Growth-promoters are banned by the European Community, but different hormonal cocktails are still illegally used. This experiment was therefore conducted to evaluate the effects of one of the most currently used cocktails on some hormonal parameters and spermatogenesis in finishing bulls in an attempt to provide a suitable screening technique for their illegal use. Sixteen double-muscled Belgian White Blue finishing bulls (mean ivcight: 535 (s.d. 37) kg) were blocked into control (C; no. = 7) and treated (Dex; no. = 9) groups. Animals were treated i.m. with the hormonal preparation (dexamethasone isonicotinate and phosphate, chlormadinone acetate and ethinyl oestradiol) on day 0, day 15 and day 30. Animals were slaughtered on day 45. Three h before each treatment and just prior to slaughter, jugular blood samples were collected to monitor the testosterone (T) response to an i.v. injection of gonadotropin releasing hormone (GnRH) (0·5 fig GnRH per kg body weight). Testicular tissue was also collected at slaughter. Plasma T and insulin-like growth factor-1 (IGF-1) concentrations were measured by radioimmunoassay. IGF-binding proteins (IGFBPs) were evaluated using Western ligand blotting. Daily weight gains were lower in the control group (1·29 (s.d. 0·13) kg for C v. 1·60 (s.d. 0·39) kg for Dex) but the difference ivas not significant. After treatment, spermatogonia, spermatocytes, spermatids and spermatozoa disappeared from the testis and seminiferous tubules consisted only of Sertoli cells; these observations suggest that treated animals were sterile. Moreover, plasma T concentrations in response to GnRH stimulation were suppressed fP < 0·001) in the Dex group between day 15 and day 45 (mean maximal responses: 5·4 to 7·9 μg/l in C group v. < 0·2 μg/l in Dex group at day 15, 30 and 45). Treatment did not show any prominent effect on plasma IGF-1 levels but increased IGFBPS band intensity. In conclusion, treatment with a cocktail containing dexamethasone esters, chlormadinone acetate and ethinyl oestradiol for a short period induced a number of changes in finishing bulls luhich might be possible to develop as a screening method for the identification of illegally treated animals.

Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves

“…The results of Sillence and Etherton (1991) and Miell et al (1993), both show elevated IGF-I by RIA. Also, Renaville et al (1994) observed no significant difference in plasma IGF-I levels (213 vs. 245 µg L -1 ).…”

“…In the human, Miell et al (1993) demonstrated that dexamethasone in normal human volunteers significantly increases IGFBP-3 levels while IGFBP-2 levels decrease. A higher level of IGFBP-3 was also reported in bulls treated with dexamethasone esters given along with estrogen and progestagen (Renaville et al 1994).…”

“…Recently, Corah et al (1995) reported that dexamethasone implants increase external fat thickness and are effective for increasing carcass muscularity and dressing percentage. We have also noted that treatment with dexamethasone esters administered along with estrogen and progestagen stimulates daily gains in finishing bulls during a short period (Renaville et al 1994).…”

Thymus atrophy and regeneration following dexamethasone administration to beef cattle

“…CORTICOSTEROIDS are used illegally in several countries as growth promoters in veal calves and beef production, in order to enhance carcase and meat quality traits (Renaville and others 1994, Gottardo and others 2008). These drugs are usually used in association with sex steroids and β‐agonists to obtain a higher proportion of lean meat (Meyer 2001).…”

Administration of dexamethasone per os in finishing bulls. I. Effects on productive traits, meat quality and cattle behaviour as indicator of welfare

“…Various studies have been performed to assess the effects of non-therapeutic dexamethasone use on beef cattle growth and slaughter performance (Brethour, 1972;Dicke et al, 1974), while others (Renaville et al, 1994;Corah et al, 1995) also considered metabolic parameters and nutrient partitioning hormones. None of the abovementioned works considered cattle welfare, however, which is currently one of the most important issues for the consumer (McGlone, 2001).…”