What Are the Effects of Bovine Growth Hormones?
Bovine somatotropin (BST) is a bovine growth hormone that affects milk production in dairy cows. It is a naturally occurring hormone produced by the cow's pituitary gland. Scientists have established methods by which the hormone can be reproduced in laboratory settings, and dairy cattle can be injected with it in order to increase milk production. There is some controversy and concern surrounding the use of BST, but much of it is largely unfounded.
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Production
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Originally, the only source of bovine growth hormone was the pituitary gland of dead cattle. This method, however, produced very little of the hormone. Since those days, a process was developed to mass-produce bovine growth hormone in amounts previously impossible.
Scientists, after determining which gene controls production of bovine growth hormone, were able to insert the gene into the escherichia coli bacteria (E. coli). This method allowed for larger scale production of bovine growth hormone in a laboratory setting.
Function
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Bovine somatotropin, once it's injected into a cow's bloodstream, can vastly increase milk production in the animal. According to Office of Biotechnology at Iowa State University, bovine somatotropin is believed to increase blood flow to the cow's mammary gland, which increases milk production. Cows injected with BST generally see an increase in daily milk production anywhere from 4.8 to 11.2 lbs. per day. In order for their bodies to keep up with the increase in production, cows treated with BST will eat more. According to Office of Biotechnology, treated cows will increase their intake of grain and forage by anywhere from 10 to 20 percent.
Effects on Cattle
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According to the Office of Biotechnology at Iowa State University, high doses of BST cause increased calf deaths in the embryonic stage. This means that BST during a cow's early stages of pregnancy should be avoided. Such high doses, however, exceed the recommended dosage and should be avoided.
Other effects include a lengthening of calving intervals and do not, contrary to some early concerns, include infection of the cow's mammary gland. BST does not affect how long the cows gestate, the size and weight of calves, the calf survival rate, or the calves' growth.
Effects on People
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According to the Office of Biotechnology at Iowa State University, the "biological activity of commercial BST is identical to natural BST." Bovine somatotropin ingested via a human's digestive system has no effect on the human. The digestive system breaks the BST down into amino acids and peptides, which remain inactive. Human growth hormone (or human somatotropin) has different amino acids than BST, which prevents BST from having any effect on humans. Milk produced by BST injected cattle is perfectly safe for human consumption.
Controversies
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The U.S. Food and Drug Administration (FDA) regulates BST. The FDA has found no evidence that milk from BST treated cows causes any diverse side effects through human consumption. Gastric enzymes in the human stomach effectively destroy any BST from the milk.
Still, some controversy remains. According to food safety specialist Charlotte P. Brennand, Ph.D., most of this controversy comes from fears within the dairy industry. Farmers who don't give BST to their herds fear competition from farmers who do. Processors and milk producers fear BST may adversely affect their business if consumers, despite studies that prove otherwise, feel BST may be harmful to them.
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