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Somatotropin (ST) is a protein hormone produced in the pituitary gland of all vertebrates including cattle. Bovine somatotropin is abbreviated bST or BST. It is also called bovine growth hormone, or BGH.
BST can be produced synthetically, using recombinant DNA technology. This is called "recombinant bovine somatotropin" rBST or "recombinant bovine growth hormone" rBGH.
Human growth hormone is abbreviated hGH or HGH. The word recombinant refers to synthetically produced human growth hormone, rHGH.
Additional recommended knowledge
Because of protein homology, Bovine Growth Hormone (GH) cross-reacts with the receptors of prolactin and placental lactogen — two hormones that stimulate the mammary tissue of a mature lactating cow in good health to produce more milk.
Protein hormones are large. The hormone does not pass through the placenta to fetal calves. It does not pass through the lining of the digestive system, and is broken down in the digestive system.
The sequence and 3D structure of the bovine growth hormone protein are different from the human growth hormone protein. Protein hormones require a "lock and key" type interaction with other compounds in the body to function, so any changes in sequence or structure would inhibit function. In other words, BGH will not function as a human growth hormone.
Uses in agriculture
"In 1937 scientists observed that milk yield increased when BST was administered to lactating cows. From the '30s through the early '80s, knowledge on chemical structure, function and activity of ST from several animal species increased. Supplies of ST were limited during this period to what could be extracted from the pituitary glands of slaughtered animals."
Monsanto developed a recombinant version of BST, which goes by the brand name POSILAC®. Growth hormones associated with injections given to dairy cows to increase milk production are known under an assortment of terms, but these terms generally refer to the same Monsanto product sold under this brand name.
Production of rBST
While specific information about the production of rBST is proprietary, the technology is commonly used to produce other proteins such as human insulin.
In short, the gene for a protein of interest is cloned into a bacterial plasmid. Bacteria, usually a non-virulent type of E. coli, undergo transformation. Bacteria that receive the plasmid will produce the protein product of the gene. The protein can then be purified from bacterial extract. This is considered an instance of genetic engineering, since mammalian hormones are not naturally present in the proteomes of bacteria. Note that it is the bacteria used to produce rBST, and not the cows to which it is administered, to which the term "genetically engineered" is applied.
Use of Posilac
Posilac prevents mammary cell death in dairy cattle. As such, it does not increase milk production on a day-to-day basis, but rather prevents milk production from decreasing over the long term, thus resulting in higher overall production during a lactation. Because a cow's milk production increases and decreases during her lactation based upon a known curve, application of Posilac can be carefully planned to maximize results.
An average dairy cow begins her lactation with a moderate daily level of milk production. This daily output increases until, at about 70 days into the lactation, production peaks. From that time until the cow is dry, production slowly decreases. This increase and decrease in production is partially caused by the count of milk-producing cells in the udder. Cell counts begin at a moderate number, increase during the first part of the lactation, then decrease and the lactation proceeds. Once lost, these cells generally do not regrow until the next lactation.
To apply Posilac for maximum effect, farmers are recommended to make the first Posilac application about 50 days into the cow's lactation, just before she peaks. The Posilac then prevents mammary cell death, limiting the rate of production decrease after production peaks. After the peak, production declines with or without application of Posilac, but declines more slowly with Posilac than without. This decrease in the rate of production decline permits dairy cows to produce more milk over the span of a lactation - at its best, this will be seen by seven to eight more pounds of milk being produced per day than would be produced without the benefit of Posilac.
Controversy about rBST
Use of rBST has been held in controversy for a variety of reasons, including: animal health concerns, human health concerns, and the encroachment on small farmers by large corporations.
Mastitis and other health concerns in animals
In 2003, a meta-analysis on rBGH's effects on bovine health was published in The Canadian Journal of Veterinary Research. The article states that rBGH "was found to increase the risk of clinical mastitis by approximately 25% during the treatment period." "Use of rBST increased the risk of a cow failing to conceive by approximately 40%." Treated cows had a "an estimated 55% increase in the risk of developing clinical signs of lameness (moving with pain or difficulty on account of injury, defect, or temporary obstruction of a function)."
The movie The Corporation has a segment on rBGH. This includes video of cows suffering from mastitis.
"Dairy records demonstrate an association between milk yield and incidence of mastitis. This association suggests that incidence of mastitis would increase in BST-treated cows because they produce more milk. This has been observed in some BST studies. The incidence of mastitis is increased because BST makes the cow generate a greater milk yield."
Dairy farmers usually treat mastitis with antibiotics. "Although increased milk yield is associated with an increased incidence of mastitis, proper management practices can minimize the frequency and impact of mastitis. Not every mastitis case requires treatment of the cow with antibiotics. All milk is tested for the presence of antibiotics before it is marketed and dairy producers realize they must not ship milk contaminated with antibiotics. Producers incur significant financial penalties if they ship antibiotic-contaminated milk. Dairy producers have considerable incentive to follow established guidelines for antibiotic use. Use of BST will not increase the incidence of antibiotic contamination of the milk supply if producers use antibiotics as directed." Milk found to contain antibiotics is discarded.
The claim by rBST proponents, therefore, is that mastitis is not caused specifically by treatment with BGH or rBGH, but is caused in general by the increased levels of milk production, whether promoted by rBGH or other methods. Cows that naturally produce more milk are more likely to experience mastitis. Similarly, cows that produce more milk require more services (fertilization attempts) than cows that produce less milk. Selective breeding of dairy cows has greatly improved milk yield over the years, but has also increased incidence of mastitis and other health problems in dairy cattle.
rBGH, however, has been associated with an increased risk of mastitis in cows. The warning label on Monsanto’s Posilac explicitly states, "Cows injected with Posilac are at increased risk for clinical mastitis." The EU Scientific Committee on Animal Health and Animal Welfare (SCAHAW) was asked to report on the incidence of mastitis and other disorders in dairy cows and on other aspects of the welfare of dairy cows. The Committee stated
"bST (Bovine somatotropin) use substantially increases foot problems, mastitis and injection site reactions in dairy cows. These conditions are painful and debilitating, leading to significantly poorer welfare of the animals. bST also causes reproductive disorders. Therefore, from the point of view of animal welfare and health, this substance should not be used."
"The veterinary experts cited an increased risk of mastitis of up to 25%, of infertility by 18%, and of lameness by up to 50%. These increased risks and overall reduced body condition lead to a 20-25% increased risk of culling from the herd."
Monsanto's studies show use of rBGH in cows increases bovine insulin growth factor 1 (IGF-1) in milk. Bovine IGF-1 and human IGF-1 are identical in structure.  and indistinguishable by available immune assay methods.
Human health concerns
Most countries, including Canada and the European Union, have not approved rbST for use due to public health and animal welfare concerns.
Proponents of rBGH use claim that this disapproval is an attempt to impose unfair trade restrictions.
BGH proponents argue that cross-species differences are significant enough to prevent most cross-species effects. (i.e. bST does not "work" in humans.) Monsanto, the largest single producer of rBGH has repeatedly stated that the amounts are too small and digestion too complete for them to have any direct effect in humans. They state that there is no scientifically verifiable difference between milk from treated versus untreated cattle.
According to Monsanto and the various government regulatory bodies which have reviewed rbST, milk and meat from cattle supplemented with rbST are safe. Monsanto also states that the only difference between milk from supplemented cattle and unsupplemented cattle is the amount of insulin growth factor 1 (IGF-1) — and that there is not even a difference in the concentration of bST.
Opponents counter that indeed there are differences aside from the higher rate of IGF-1, most importantly that BGH and rBGH (rbST) have a different chain of amino acids. This difference "can markedly change the immunogenic characteristics of a protein". Whether the change in immunogenic characteristics brought about by rBGH actually poses a threat to consumer health has yet to be demonstrated.
Canada's health board, Health Canada, commissioned a study which found "no biologically plausible reason for concern about human safety if rbST were to be approved for sale in Canada. The only exception to this statement is [possible hypersensitivity]."
IGF-1 is important for normal development. However, several studies have identified correlations between elevated levels of IGF-1 and undesirable conditions or diseases. These studies have not concluded that elevated IGF-1 causes undesirable conditions or diseases, nor have they concluded that the undesirable conditions or diseases cause elevated IGF-1.
According to Monsanto, IGF-1 is negligibly increased through milk consumption: the amount of IGF-1 contained in 1.5 litres of milk is less than 1% of the IGF-1 that is daily produced by the human body. 
Particularly, some studies found that IGF-1 levels in the human blood stream are elevated in patients with breast, prostate or colorectal cancer. In 1998, the American Cancer Society reported a correlation between human blood levels of IGF-1 (often associated with obesity) and breast cancer, prostate cancer, and colorectal cancer. Increased plasma levels of IGF-1 are associated with a higher risk of diabetes and a shorter lifespan in animal studies (e.g. Nature, vol 444, pages 337-342, 2006). On May 22, 2006, Scientific American reported that Dr Gary Steinman of the Long Island Jewish Medical Centre published a paper in the Journal of Reproductive Medicine proposing a link between IGF and the incidence of twin births. He cites the May 6 issue of The Lancet which compared the relative increase of twinning rates in the USA and UK.
Increased plasma levels of IGF-1 are associated with a higher risk of diabetes and a shorter lifespan in animal studies (e.g. Nature, vol 444, pages 337-342, 2006).
Milk production in North America, Europe, and Australia is already plentiful and milk is generally inexpensive. Those opposing the use of the drug have expressed concerns that using the drug to increase milk production (hence depressing prices) primarily benefits large scale producers and will narrow the margins that small dairy farms receive for their products.
Lawsuit against Fox television
After a five-week trial and six hours of deliberation which ended August 18, 2000, a Florida state court jury unanimously determined that Fox "acted intentionally and deliberately to falsify or distort the plaintiffs' news reporting on BGH." In that decision, the jury also found that Akre's threat to blow the whistle on Fox's misconduct to the FCC was the sole reason for the termination... and the jury awarded $425,000 in damages which makes her eligible to apply for reimbursement for all court costs, expenses and legal fees.
Fox appealed and prevailed February 14, 2003, when an appeals court issued a ruling reversing the jury, accepting a defense argument that had been rejected by three other judges on at least six separate occasions. The appeals court's decision on the verdict was on the basis that FCC policies on news agencies reporting the truth did not legally require the station to report the truth in a news story, as FCC policies are not law. The story that was subsequently reported on BGH contained no statistics that may have indicated a human health risk, as these statistics (the ones found by Akre and Wilson and mentioned in their original story) were ignored.
This story is featured in length in the documentary: The Corporation.
Banned outside the United States
The sale of Posilac is illegal in virtually every developed country with the exception of the United States.  In the United States, the use of rbST has been approved by the FDA.
In Japan, Australia, New Zealand, and Canada, rbST is not approved for use. 
The European Union declared the use of rbST as safe in 1990, but in 1993, a moratorium was placed on its sale by all 27 member nations.
Canada's health board, Health Canada, refused to approve rBGH for use on Canadian dairies, citing concerns over animal health. The study they had commissioned, however, found "no biologically plausible reason for concern about human safety if rbST were to be approved for sale in Canada. The only exception to this statement is... (possible hypersensitivity)."
Regulation inside the United States
In November 1993, the product was approved for use in the U.S. by the FDA, and its use began in February 1994. The product is now sold in all 50 states. According to Monsanto, approximately one third of dairy cattle in the U.S. are injected with Posilac; approximately 8,000 dairy producers use the product. It is now the top selling dairy cattle pharmaceutical product in the U.S.
A great deal of controversy within the FDA surrounded Posilac's evaluation in the late 1980s. Richard Burroughs, who had a lead role in the review process, was shocked at how few tests the agency was requiring. Burroughs ordered more tests but was soon fired. He said, “I was told that I was slowing down the approval process.” Alexander Apostolou, director of the FDA's Division of Toxicology, says, “Sound scientific procedures for evaluating human food safety of veterinary drugs have been disregarded.” When he expressed his concerns at the agency, he was pressured to leave.
Chemist Joseph Settepani testified at a public hearing about “a systematic human food-safety breakdown at the Center for Veterinary Medicine.” Prior to his testimony, he was in charge of quality control for veterinary drug approvals. Soon after, he was stripped of his duties as a supervisor and sent to work in a trailer at an experimental farm. On March 16, 1994, others at the FDA resorted to writing an anonymous letter to members of Congress, saying they were “afraid to speak openly about the situation because of retribution."
The Food and Drug Administration (FDA) does not require special labels for products produced from cows given rbST. Monsanto sued the Oakhurst Dairy over their use of a label which read: "Our Farmers' Pledge: No Artificial Growth Hormone."
Monsanto stated: "We believe Oakhurst labels deceive consumers; they're marketing a perception that one milk product is safer or of higher quality than other milk. Numerous scientific and regulatory reviews throughout the world demonstrate that that's unfounded. The milk is the same, and the amount of protein, fats, nutrients, etc., are all the same."
Oakhurst's President stated: "We have said from the beginning that we make no claims to understand the science involved with artificial growth hormones. We're in the business of marketing milk, not Monsanto's drugs."
The suit was settled when Oakhurst agreed to add a qualifying statement to their previous label, reading: "FDA states: No significant difference in milk from cows treated with artificial growth hormone."
The FDA has charged several dairies with selling "misbranded" products, based on labels stating that their milk was "hormone free" or contained "no hormones". The FDA states that all milk contains hormones and "milk cannot be produced in a way that renders it free of hormones."
Demand for organic milk (produced without the use of synthetic hormones) in the US has increased 500% since Monsanto introduced their rbST product; organic milk is the fastest growing sector of the organic food market. Shortages exist, and not enough organic milk is produced to meet demand.
Use of the recombinant supplement has been controversial. While it is used in the United States, it is banned in Canada, parts of the EU (The EU's stance leaves the decision up to individual nations, though none have allowed it), Australia, and New Zealand.
Banning of "rBGH/rBST-free" labeling in Pennsylvania
Beginning February 1, 2008, the U.S. state of Pennsylvania will ban so-called "absence labeling", which includes milk labeled "rBGH/rBST-free."  The ban was postponed from an original start date of Jan. 1 to give interested parties more time to debate the move.
Voluntary removal of rBGH from the milk supply
No milk is free of BST.  However, several milk purchasers and resellers do not purchase milk produced with rBGH. As of February 2007, Safeway in the Northwestern United States stopped buying from dairy farmers that use rBGH. The two Safeway plants produce milk for all of Oregon, Southwest Washington, and parts of northern California. Safeway's plant in San Leandro, CA had already been rBGH-free for two years. Trader Joes supermarkets only sell rBST-free milk, be it organic or not. Their non-organic rBST-free milk is not more expensive than major supermarkets' milk. Alpenrose Dairy in the Northwest has also stated that all of their dairy products are rBGH free.
Another company going rBGH free is Chipotle Mexican Grill that has also announced it will only serve rBGH-free sour cream at its more than 530 restaurants. Kroger Company has announced its intent to sell only milk produced without synthetic hormones by February 2008.Publix Supermarket Consumer Relations department says "Publix milk has been rBST/rBGH free since May of this year  and is readily available in all fat levels and sizes at your neighborhood Publix." Braum's Ice Cream & Dairy Stores (Oklahoma, Texas, Kansas, Arkansas and Missouri only) does not add rBGH to any of their cows.  However, with no way to test for rBGH/rBST in milk, these claims are unsubstantiated and may be false.
References regarding Monsanto
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bovine_somatotropin". A list of authors is available in Wikipedia.|