Bovine growth hormone
Bovine growth hormone (BGH), also known as bovine somatotropin, is a protein naturally produced by the anterior pituitary gland in cattle that regulates growth and milk production. Its synthetic form, recombinant bovine somatotropin (rBST), is administered to dairy cows to enhance milk yield by approximately 10%. The use of rBST has sparked significant debate, particularly regarding its safety and potential health risks associated with milk consumption. Although the U.S. Food and Drug Administration (FDA) has approved rBST and consistently affirmed its safety, several countries, including those in the European Union and Canada, have banned its use, often citing political and economic factors rather than scientific evidence.
Advocates argue that rBST could improve environmental sustainability by allowing fewer cows to produce the same amount of milk, reducing land use and waste. However, concerns remain about the treatment of cows, as rBST can lead to a higher incidence of mastitis, which is managed with antibiotics. Some major grocery chains have opted not to sell milk from rBST-treated cows, despite the milk's indistinguishability from that of untreated cows. As such, the topic continues to evoke diverse opinions regarding agricultural practices, animal welfare, and consumer safety.
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Bovine growth hormone
DEFINITION: Protein secreted by the anterior pituitary gland in cattle that controls the rate of skeletal and visceral growth
The administration of growth hormone to dairy cattle to increase milk production is controversial because of unsubstantiated allegations about the safety of the milk produced. It is also argued, however, that increasing the efficiency of milk production would benefit the environment by reducing the amount of feed needed and the waste produced per unit of production.
Growth hormone is produced by all vertebrate animals to control their rate of growth. Prior to the development of biotechnology, acquiring growth hormone was a laborious process, involving extraction from the pituitary glands of cadavers or slaughterhouse animals. All early studies of the hormone were dependent on these sources. Advances in biotechnology, however, now permit the efficient production of synthetic growth hormone, referred to as recombinant growth hormone. Recombinant human growth hormone is used to treat growth retardation conditions in children.
Recombinant bovine growth hormone, also known as recombinant bovine somatotropin, or rBST, is administered to beef cattle to increase their growth rate and administered to dairy cattle to increase their milk production. The Monsanto Company developed and tested the first such product, which it called Posilac. In 1993, the US Food and Drug Administration (FDA) approved the use of Posilac, which increases milk production by at least 10 percent and has not been found to be harmful to cattle or human consumers. Over the intervening years, the FDA has continued to affirm the safety of the product, despite continuing controversy about it and bans on its use by European, Canadian, and other governments.
To be effective, rBST must be injected because, as a protein, it would be degraded by the digestive system if administered orally. The milk of injected cows is indistinguishable from that of noninjected cows, with the exception of slightly elevated insulin-like growth factor (IGF-1), although the latter remains within the physiological range of human breast milk. In any event, as a protein, IGF-1 is degraded in the human digestive system. Nevertheless, concerns have been raised about the health risks to consumers of milk from treated cows. None of these have been substantiated by any reputable scientific review in the United States or elsewhere. It has been argued that the bans by the European Union and Canada are based on political and economic considerations, with the governments protecting quota-based milk-production systems that would be disrupted by this product. From an environmental perspective, the ability to have fewer cows (using less land, consuming less feed, and generating less waste, including the greenhouse gas methane) producing the same amount of milk that would be produced by larger numbers of untreated cows is a definitive benefit.
The cattle injected with rBST are metabolically equivalent to genetically improved cattle and must be fed and treated as such. Like any high-producing cows, they have a slightly increased incidence of mastitis, an infection of the mammary gland, although it remains lower per gallon of milk produced. Mastitis is treated with antibiotics, and any milk with antibiotic residue must be withheld from the market. The assertion that rBST-treated cows are increasing the antibiotic content of the milk supply is unsupported by any evidence. Nevertheless, a number of American grocery chains and food companies indicated that they will not sell dairy products from cows injected with rBST. For example, Kroger, Publix, Costco, and Walmart have used non-growth hormone sources for their private label milk products since the late 2000s. However, given that the milk of rBST-treated cows is virtually indistinguishable from that of untreated cows, it is difficult, if not impossible, to verify the compliance of their suppliers.
Bibliography
"Bovine Somatotropin (bST)." US Food and Drug Administration, www.fda.gov/animal-veterinary/product-safety-information/bovine-somatotropin-bst. Accessed 16 July 2024.
Grace, Eric S. Biotechnology Unzipped: Promises and Realities. Rev. 2nd ed. Washington, DC: Joseph Henry, 2006. Print.
Hammond, Bruce G. “The Food Safety Assessment of Bovine Somatotropin (bST).” Food Safety of Proteins in Agricultural Biotechnology. Boca Raton: CRC, 2008. Print.
Schacter, Bernice. Issues and Dilemmas of Biotechnology: A Reference Guide. Westport: Greenwood, 1999. Print.