Testosterone cattle

For protection of domestic cattle, feeds should contain <0.05 mg diflubenzuron/kg FW. Cottonseed may be added to cattle diets provided that diflubenzuron concentrations in the seed do not exceed 0.2 mg/kg FW and that cottonseed composes <17% of the total diet bulk (Gartrell 1981). Diflubenzuron causes biochemical upset, as judged by lowered testosterone levels in chickens and rats (USEPA 1979), altered glutathione 5-transferase activity in mouse liver (which adversely affects the ability to detoxify foreign substances by way of conjugation Young et al. 1986), and disrupted hydroxylamine activity in human infants (USEPA 1979). Additional research seems needed on biochemical alterations induced by diflubenzuron. No diflubenzuron criteria are currently recommended for protection of avian and mammalian wildlife. All data available suggest that wildlife species are about as tolerant to diflubenzuron as are domestic poultry and livestock however, the wildlife database seems inadequate for practicable criteria formulation. 

In a similar type of data collection, during 2000 to 2001 Wozniak (2002) examined the incidence of anabolic hormone residues in 5393 animals, consisting of cattle, pigs, horses, rabbits, chickens, geese, turkeys, ducks, and fish. Wozniak assayed for residues of diethylstibestrol, hexesterol, dienestrol, zeranol, trenbolone, and 19-noresterone. In addition, 632 cattle and swine were assayed for medroxyprogesterone and 1176 were assayed for natural 17-p-estradiol and testosterone. In only three heifers and two cows did serum testosterone exceed the MRL (EC 0.5 pg per liter) two bulls and four cows had an increased content of 17-(3-estradiol in their blood. A total of 11 animals of the 5393 examined (0.2%) had excessive quantities of hormone materials in their system. None of the other animals showed evidence of the presence of... 

Two female sex hormones, estradiol-17 and progesterone, and one male sex hormone, testosterone, are used as growth promoters on beef cattle (Fig. 7.1). By nature, they are all endogenous products playing an important role in controlling reproductive functions in humans and animals. When applied exogenously they will enter the same metabolic pathways as the endogenously produced molecules. 

Testosterone is used for growth-promoting purposes in cattle as an subcutaneous implant in the ear, in combination with estradiol or its esters. It is usually administered in the form of its acetate, propionate, or isobutyrate esters. 

In all species, metabolism of testosterone leads to its biological deactivation. In sheep and cattle, this biological deactivation leads mainly to formation of epitestosterone, whereas in nonruminants it leads to androsterone, etiocholano-lone, and dehydroepiandrosterone (7-9). Residues of endogenous testosterone are usually highest in the kidneys of animals such as heifers witli a low testosterone production rate, and highest in fat of animals such as bulls, with a high production rate. 

Trenbolone acetate is a synthetic steroid with hormonal activity similar to testosterone but with greater anabolic activity. After administration to cattle, trenbolone acetate is rapidly hydrolyzed to its free hydroxylated form (28). The 17 -OH epimer is the major metabolite occurring in the excreta, bile, and liver. 

A survey carried out in Austria between 1991 and 1993 demonstrated that the incidence of residues of veterinary drugs and hormones in edible tissues of slaughtered animals was almost negligible (7). In particular, urine samples obtained from calves, cows, and swine were tested for the presence of residues of stilbenes, zeranol, trenbolone and 19-nortestosterone. Blood samples were examined for 17- -estradiol and 17- -testosterone. Furthermore, urine samples from calves, beef cattle, and thyroid gland specimens were tested for the presence of -agonists and thyreostatic substances. None of the samples gave evidence of illegal use of these substances in Austria. 

The U.S. Food and Drug Administration policy is based on the conclusions of the Joint FAO/ WHO Expert Committee on Food Additives (JECFA). In its Thirty-Second Report (1988), it concluded, on the basis of its safety assessment of residues of estradiol-17/3, progesterone, and testosterone, and in view of the difficulty of determining the levels of residues attributable to the use of these hormones as growth promoters in cattle, that it was unnecessary to establish an acceptable residue level. As to trenbolone acetate (TBA), a synthetic steroid with anabolic properties, JECFA concluded that its safety assessment could be based on establishing the no-hormonal-effect level. It therefore recommended a maximum residue level of 2 /zg/kg for /3-tren-bolone in meat and of 10 /xg/kg for a-trenbolone in liver on the basis of a daily intake by a 70-kg person of 500 g of meat. /3-Trenbolone is the major metabolite in muscle. For zeranol, an acceptable residue level of 10 /xg/kg for bovine liver and 2 /zg/kg for bovine muscle was established. 

Androgens are classical anabolic agents in humans, but they are less effective in farm animals like cattle due to their lower androgen receptor concentrations [14]. Testosterone is not used on its own as an anabolic agent in farm animals because of the inadequate delivery systems available for achieving effective concentrations. It is used in conjunction with estradiol. Its major role may be to slow down the release rate of estradiol. 

For protection of domestic cattle, feeds should contain <0.05 mg diflubenzuron/kg FW cottonseed may be added to cattle diets provided that diflubenzuron concentrations in the seed do not exceed 0.2mg/kg FW and that cottonseed composes <17% of the total diet bulk. Diflubenzuron causes biochemical upset, as judged by lowered testosterone levels in chickens and rats, altered... 

Srinivas and Srinivasulu (1993) found that heulandate layers developed with carbon disulfide-pyridine (1 1) were effective for the separation of steroid hormones,—dehydroepiandrosterone could easily be separated from mixtures of cholesterol and estradiol benzoate or testosterone phenylpropionate, and testosterone could be separated from mixtures of cholesterol and testosterone phenylpropionate or estradiol benzoate. Likewise, estradiol could easily be separated from mixtures of cholesterol and estradiol benzoate. Daeseleire et al. (1994) applied HPTLC and GC/MS for the detection of anabolic steroids used as growth promoters in illicit cattle fattening within the European market. Agrawal et al. (1995) developed a sensitive, reliable, and rapid silica gel TLC method for the separation, identification, and quantification of stereospecific androgen metabolites. 

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