Bovine somatotropin

RBST redirects here. For information on the computational algorithm, see RBST (algorithm).

Bovine somatotropin (bST), or bovine growth hormone (BGH), is a protein hormone that occurs naturally in the pituitary gland of cattle. It is a factor controlling the amount of milk produced by a dairy cow. Bovine somatotropin is naturally in the milk extracted from a cow.

Physiology

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.

Somatotropin and somatropin both refer to growth hormone (GH), a protein hormone produced by the mammalian anterior pituitary. The genes for GH, the amino acid sequence of the peptides, the receptor genes, and the receptor structures are recognizably homologous, though cross-species differences are significant enough to prevent most cross-species effects. (i.e. bST does not "work" in humans.) (Source) Although bST, insulin-like growth factor 1 (IGF1), and other cow hormones can be measured in cow milk, Monsanto has repeatedly claimed that the amounts are too small and digestion too complete for them to have any direct effect in humans, and there is no scientifically verifiable difference between the rBST concentration in milk from treated versus untreated cattle.

Recombinant Bovine Somatotropin (rbST) and rBGH

rbST (Recombinant Bovine Somatotropin) or rBGH (Recombinant Bovine Growth Hormone) is a controversial, genetically engineered version of the Bovine Growth Hormone used for increasing milk production in cows.

Monsanto developed a recombinant version of bST (rbST), 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 generally refer to the same Monsanto product sold under this brand name. Other terms include, rBGH, BGH, rBST, BST and GH.

Injected into dairy cattle, the product can increase milk production from 10% up to 40%.

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 13,000 dairy producers use the product. It is now the top selling dairy cattle pharmaceutical product in the U.S. The Food and Drug Administration (FDA) does not require special labels for products produced from cows given rbST.

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 it up to separate nations), Australia, and New Zealand.

Many groups claim not enough research has been done into human health effects, and claim a possible increased risk of diabetes and hypertension in consumers of products from rbST injected cows . Other fears include health problems for the injected cattle, and an economic concern for small farmers due to the increased supply of milk.

According to Monsanto, 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 insuline growth factor 1 (IGF-1) — and that there is not even a difference in the concentration of bST.

In 1998, a Canadian committee found that while there were no significant risks to human health, there may be increased risks to animal safety due to injections of rbST. According to their report, use of rbST increased the risk of mastitis by up to 25%, infertility by 18%, and lameness by up to 50%. The hormone is banned in Germany under its laws prohibiting cruelty to animals.

Humans who have too much (human) growth hormone can develop a disease called acromegaly; some speculate that it is no more healthy for cows to have too much growth than it is for humans, despite the fact that somatotropin does not noticeably stimulate physiological maturation and was even refined from slaughter cattle and used in medical attempts to treat dwarfism in humans in the 1930s, to no positive or negative effect .

Many animal rights activists oppose any farming practice that seems to "industrialize" food production from animals in an artificial way, because they fear for the animal's well being. Monsanto claims rBST only has physiological effects on cattle in good health.

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. Whether this is problematic or not is an economic debate.

National Policies

In the United States, the use of rbST is permitted.
In Canada, rbST is not approved for use. rbST was rejected by Health Canada, which ruled that use of the synthetic hormone "a sufficient and unacceptable threat to the safety of dairy cows".
The European Union declared the use of rbST as safe in 1990, but in 1993, a moratorium was placed on its sale by all 25 member nations. This could be a non-tariff barrier to protect subsidized European milk producers.
Japan and New Zealand have banned the product.

IGF-1

Use of rBGH in cows also increases insulin growth factor 1 (IGF-1) in milk. Although IGF-1 is important for normal development, some studies suggest that IGF-1 is involved in the progression of breast, prostate and colorectal cancer Although the American Cancer Society asserted "there are no valid scientific findings to indicate a risk of human carcinogenisis" regarding rbST ^*," target="_blank" >Prostate Cancer ^*.

Scientific Studies

Report of the Royal College of Physicians and Surgeons of Canada Expert Panel on Human safety of rbST ^*
Report of the European Commission Scientific Committee on Veterinary Measures relating to Public Health on "Public Health Aspects of the Use of Bovine Somatotrophin" ^*

References

Science and technology: Udder confusion. Anonymous. The Economist. London: Jul 3, 1999.Vol.352, Iss. 8126; pg. 70, 2 pgs.
Big Milk, Big Muscle, Big Money. Fifth Estate - CBC Television. Toronto: Nov 29, 1994.
U. S. Food and Drug Administration Center for Food Safety and Applied Nutrition / Cornell University BST Fact Sheet ^*
IGF-1 and Milk.com (link articles) ^*

External references

Growth hormones | Peptide hormones

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