Growth promoters in cattle

Some of these compounds could be considered as dietary additives, but various other terms, including pesticides, can also be used. They can have beneficial effects on the environment and this aspect will be discussed later. The ionophore monensin, which is an alicyclic polyether (Figure 1), is a secondary metabolite of Streptomyces and aids the prevention of coccidiosis in poultry. Monensin is used as a growth promoter in cattle and also to decrease methane production, but it is toxic to equine animals. " Its ability to act as an ionophore is dependent on its cyclic chelating effect on metal ions. ° The hormones bovine somatotropin (BST) and porcine somatotropin (PST), both of which are polypeptides, occur naturally in lactating cattle and pigs, respectively, but can also be produced synthetically using recombinant DNA methods and administered to such animals in order to increase milk yields and lean meat production. "... 

Monensin plays a dual role in veterinary practice because it is used both as a coccidiostat in poultry and as a growth promotant in cattle. It is also efficacious in the control of coccidiosis in lambs and calves, can treat ketosis in dairy cows, and can control bloat in pastured dairy cattle. It is administered incorporated in poultry feeds as a coccidiostat at a dose up to 120 ppm, and in cattle and sheep feeds at a dose of 11-33 ppm. Monensin is not recommended for administration to laying hens, while a 3 day withdrawal period is required for chicken meat. 

Lasalocid is widely used for controlling poultry coccidiosis since it is very efficient against all species of Eimeria at the optimal dose of 90 ppm in the feed. It is licensed for use in broilers and hens up to 16 weeks from hatching but is not licensed for use in laying hens. It has been also used as a growth promoter in cattle. 

Progesterone is used primarily as a growth promotant in cattle in combination with estradiol or its esters. Administration is carried out by subcutaneous implant in the ear, which is subsequently discarded at slaughter. When administered exogenously, progesterone enters the same metabolic pathways and is indistinguishable from the endogenously produced compound. 

Nortestosterone and its derivatives are banned for use in livestock production within tlie European Union, but have been abused as growth promoters in cattle (17). Abuse can be detected by finding injection sites at slaughter and also by monitoring bile and urine for 17 -19-nortestosterone and/or its 17 -epimer, the major metabolite in cattle (18, 19). However, it is known that 17 -19-nortes-tosterone occurs naturally in pregnant cows (20), and 17 -19-nortestosterone is produced in boars (21) and stallions (22). To evade detection of injection sites at slaughter, some producers have used either multiple injections of small volumes at obscure sites or pour-on formulations. 

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. 

Anabolic steroids are also used, usually illegally, by some athletes as an ergogenic aid (a technique or substance used for the purpose of enhancing performance). The doses used for these purposes are many times the therapeutic dose, and some products may be used that are licensed only as growth-promoters in cattle rearing. The health risks are considerable and well documented. 

Nielen et al. (2001) focused on a related facet of the illegal use of growth promoters in cattle, namely the detection of anabolic steroids in illegal cocktails. They presented a Q-TOF LC-MS-MS method with the aim of measuring accurate mass and calculating elemental composition for identification purposes. 

Zearalenone Fusarium graminearum Zearalenone, growth promoter in cattle... 

Daeseleire, E., Vanoosthuyze, K., and Van Peteghem, C. (1994). Application of high-performance thin-layer chromatography and gas chromatography mass spectrometry to the detection of new anabolic steroids used as growth promoters in cattle farming. J. Chrormtogr. 674 247-253. 

B. Schiffer, A. Daxenberger, K. Meyer and H. H. Meyer, The fate of trenbolone acetate and melengestrol acetate after application as growth promoters in cattle, Environ. Health Perspect., 2001, 109, 1145-1151. 

Farmed animals tend to be subjected to compounds that can be classified more easily as drugs. In some cases, animals may encounter compounds in nature that have considerable limitations in inclusion in the diets of farmed animals. An example is the inclusion of zearalenone (Figure 1) and its derivatives in animal diets these have anabolic and oestrogenic properties " and are permitted to be used in some areas of the world but are prohibited from use in others, such as European Union countries. Thus this compound and its reduced isomers (zearalenols, zeranols) improve growth rates in animals but can cause reproductive problems, especially in pigs. Ralgro, which is a commercially prepared derivative of zearalenone, is used as an ear implant in beef cattle as a growth promoter in... 

Diethylstilbestrol, mentioned in Chapters 5 and 9 as a synthetic estrogen that is also a human carcinogen, was used in the United States from the 1950s until 1979 as a growth promoter in sheep and cattle. Small amounts of this drug, added to animal feed or implanted in the flesh of animals ears, increase feed efficiency, and it was very widely used for this purpose. 

Brambilla, G., M. Fiori, and E. Pierdominici. 1998. A possible correlation between the blood leukocyte formula and the use of glucocorticoids as growth promoters in beef cattle. Veterin. Res. Commun. 22 457 165. 

An interesting sidelight of the monensin story is the discovery of its further use as a growth promotant in ruminants. For years, synthetic chemicals had been screened for activity in cattle and sheep diets to eliminate the wasteful methane production and to increase volatile fatty acid formation (especially propionate) in the rumen, wiiich would improve feed efficiency. Although the concept was sound, no useful products resulted. Experimentation with monensin showed that polyethers have this activity and these compounds are used widely today for this purpose. ... 

In the United States, 100 times more bacitracin by weight is used as a feed additive than for human medicine. Most of this is BMD but some is the zinc salt. BMD can be used in subtherapeutic nutritional dosages for increase in feed efficiency and for growth promotion in poultry, swine, and feedlot cattle at concentrations of 2.6—33 g/t of feed (78,81,82). Prophylactic or therapeutic medicinal dosing at higher concentrations is used for necrotic enteritis in chickens, tra.nsmissa.h1e enteritis in turkeys, ulcerative enteritis in quail, dysentery in swine, and liver abcess in cattle (see Feeds and FEED ADDITIVES). 

In the USA, more than 22,000 tonnes of antibiotics are produced annually. Around 40 % thereof are used as growth promoters in the livestock and aquaculture industry. In the meantime, an estimated 80% of all pigs, cattle and poultry are treated with antibiotics. 

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. 

Lasalocids, SaUnomycin, Narasin guard against coccocidiosis. These ionophores are also used in cattle and swine as growth promoters. They generally have a different mode of action compared to other antibiotics. 

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