Bovine somatotropin

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Bovine somatotropin or bovine somatotrophin (abbreviated bST and BST), or bovine growth hormone (BGH), is a peptide hormone produced by cows' pituitary glands.^[1] Like other hormones, it is produced in small quantities and is used in regulating metabolic processes.^[1] Scientists created a bacterium that produces the hormone somatotropin which is produced by the cow's body after giving birth ^[2] and increases milk production by around 10 percent.^[3]

Recombinant bovine somatotropin (usually "rBST"), is a synthetic version of the bovine growth hormone given to dairy cattle by injection to increase milk production.

Controversy over its safety has led to it being banned in several countries, including the European Union since 1990, and Canada, Japan, Pakistan, Australia, New Zealand, and Argentina, as it has been found to increase health risks in cows. The Codex Alimentarius has not approved it as safe.

The FDA approved it in 1993, and required that any milk advertising that its cows were not treated with rBST include the disclaimer "The FDA has determined that no significant difference has been shown between milk derived from rBST treated and non-rBST treated cows".