ANABOLIC HORMONAL-TYPE GROWTH PROMOTERS

It has long been established that the sexual status of an animal controls and coordinates its growth rate and speed of fattening. Bulls grow faster and lay down more lean meat in the carcass than steers, whereas steers grow faster with a higher feed conversion efficiency than cows. These beneficial effects on animal performance are due to the sex steroids produced in the testes. 

The decreased level of androgens in castrated male cattle as a result of testicular removal leads to production of a carcass that is intermediate between that of an intact male and a female. Since the increased proportion of fat in such a carcass makes it less valuable for the health-conscious consumer, extensive research has been directed towards replacing the loss of carcass quality resulting from castration, by administration to the animals of various natural and synthetic hormonal substances, collectively called anabolic hormonal-type growth promoters. These compounds can substantially increase growth rate and improve feed efficiency and carcass composition in a process that may be highly profitable for the animal feeders. 

These beneficial effects, which are on the order of 10-40%, are achieved predominantly in ruminants. It has been estimated that use of hormonal implants can improve farmers margins by up to 30 a head for steers and 15 a head for heifers. Applications in other food-producing animals such as sheep, swine, and poultry occur to a lesser extent and, thus, are of limited importance. 

The use of anabolic hormonal-type growth promoters in ruminants can create a hormonal situation in castrates, females, and young stock that may be similar to that found in intact males and pregnant females. Accordingly, the 193 

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Unlike in the United States where some anabolic hormonal-type growth promoters are permitted, use of these compounds, either natural or synthetic, as growth promoters in meat-producing animals has not been allowed in the European Union since 1988, due to potential adverse effects to human health. Nevertheless, many anabolic hormonal-type growth promoters are still used illegally in the European Union. 

The distribution of residues of anabolic hormonal-type growth promoters in animal tissues depends on their mode of metabolism and excretion. Residues are commonly found in muscle, fat, liver, kidney, and milk, as well as in urine, bile, and feces. In general, residue concentrations tend to be higher in the excreta than in tissues. Control of the abuse of these compounds is usually carried out through the analysis of edible tissues, injection sites, kidney, fat, urine, or even feces. In recent years, use of fecal samples has become of increasing importance because of their ease of collection in intensive livestock farming. 

ANABOLIC HORMONAL-TYPE GROWTH PROMOTERS Estradiol and related 556.240 Estradiol... 

Multiresidue methods that present attractive performance characteristics in the analysis of anabolic hormonal-type growth promoters in meat are those reported by Lagana and Marino (453), and Hartmann and Steinhart (452). 

Table 29.13 Physicochemical Methods for Anabolic Hormonal-type Growth Promoters in Biological Matrices... 

Apart from the antimicrobial growth promoters, there have been some other hormonal-type compounds with anabolic activity that are administered usually... 

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