Mooooooooore Milk

Many years ago, scientists noticed a significant increase in the amount of milk that lactating cows produced when protein growth hormone, bovine somatotropin (BST), was administered. Since then this relationship has been confirmed, exciting many of those in the dairy industry, though provoking concern in many more. Through recombinant DNA technology, quantities of BST have been produced for experimental purposes, and for commercial use.

Some somatotropin is naturally produced, traveling through the bloodstream to certain tissues where it instigates a number of biological modifications. Importantly, it promotes the production of another growth hormone (IGF-1), which in combination with BST affects the mammary glands and increases fat breakdown, providing more energy for milk production. (link to diagram)

BST is produced synthetically by gene splicing technology, wherein the gene responsible for BST production is inserted into E. Coli bacteria. As the bacteria replicates, the gene itself is replicated into newly produced bacteria. These genes are extracted and purified then injected into the cow’s bloodstream.

Now, while all this seems highly beneficial, and many people definitely believe it is, the ample criticism it has sparked cannot be ignored. There is concern for dairy cattle health, their reproductive performance, and for the fitness of their milk for human consumption. Milk from these treated cows has not yet been approved for market in many countries, and after being approved in the USA was recently withdrawn to allow more thorough testing.

A higher milk yield is obviously ground breaking in the dairy industry. Hopefully more research will reduce concern.

Posted by Lauren Tardiani
Student NO. 41434738

Primary Reference

B.A. Crooker, D.E. Otterby, J.G. Linn, B.J. Conlin, H. Chester-Jones, L.B. Hansen, W.P. Hansen, et al. 2007. Dairy Research and Bovine Somatotropin. University of Minnesota. http://www.extension.umn.edu/distribution/livestocksystems/DI6337.html (accessed 26/05/07)

Secondary References

I. R. Dohoo, L. DesCôteaux, K. Leslie, A. Fredeen, W. Shewfelt, A. Preston, and P. Dowling. 2003. A meta-analysis review of the effects of recombinant bovine somatotropin. Canadian Journal of Veterinary Research. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=280709 (accessed 26/05/07)

Think Quest. http://library.thinkquest.org/19037/therapy2.html (accessed 26/05/07)

Bovine Somatotropin. 2007. http://en.wikipedia.org/wiki/Bovine_Growth_Hormone (accessed 27/05/2007)