a. Description of the product
Bovine Growth Hormone, or somatotropin, is a natural hormone that is secreted by the pituitary gland of cows after the birth of a calf and which allows the production of milk to be stimulated by mobilising the cow’s bodily reserves. Somatotropin was discovered in 1936 by a team of Soviet researchers, who then tried to reproduce it to stimulate milk production in livestock, but the technology of the time did not allow them to produce an artificial hormone. At the end of the 1970s, Monsanto’s researchers succeeded in isolating the gene responsible for producing the hormone. Through genetic manipulation, they succeeded in splicing the gene into Escherichia coli (or “colon bacillus”, a common bacteria which populates the intestinal flora of mammals, including man), so facilitating its large scale production. This genetically engineered hormone was christened “Recombinant Bovine Somatotropin” (rBST), or “recombinant Bovine Growth Hormone” (rBGH). From the start of the 1980s, the firm started to organise trials on its own experimental farms or in collaboration with universities like those of Vermont and Cornell. Injections of the hormone twice a month allowed milk yield to be increased by at least 15%, equivalent to on average a gallon, or 3.8 litres a day. The hormone rBST was launched on the market under the brand name Posilac by Monsanto in 1994, after being approved by the Food and Drug Administration (FDA).
b. The secondary effects of Posilac on milking cows
Forced production of milk beyond a cow’s natural capacity causes physiological effects which put the animal’s life in danger. It should be understood that the hormone injection disturbs the cow’s natural cycle, in which somatotropin is produced after calving to increase her milk production and to feed her young. As the calf grows, the hormone production gradually diminishes, as does the production of milk. In a traditional dairy, the cow has to be inseminated again to start the milk production cycle. But the Posilac injection allows the production of milk to be artificially maintained beyond the cow’s natural cycle. One of the consequences of upsetting the cycle is a decrease in the cow’s fertility level, sometimes dropping away to sterility. (See the Canadian Parliament Site).
Another consequence of the Posilac injection is a significant rise in the rate of mastitis, an inflammation of the udders which is quite common in high-yielding herds, and which results in pus in the milk. According to a study by the University of Vermont on an study group, the level of mastitis reached 40% among the group of cows treated with rGBH but it was only 10% among a control group, which was not treated. The severity of mastitis is measured by what is called the “somatic cell count” or “SCC”). To estimate how inflamed the udders are, one counts the number of leucocytes or white cells found in the cows’ blood: if the cell count is raised, that means traces of pus will be found in the milk. What’s more, these problems with mastitis further affect the quality of the milk because in order to treat the infections, farmers turn to injections of antibiotics, which leave residues in the milk. These same antibiotics then find their way into the consumer’s system and play a part in developing pathogenic colonies which are resistant to antibiotics.  As long ago as 1983, the scientific community was already alarmed at the massive administration of antibiotics on American farms and had delivered a petition to the FDA seeking a ban on their use.
The list of side effects is a long one, as Monsanto indicates on its packaging for Posilac. For example it lists the possibility of seeing “a rise in cases of cystic ovaries and uterine problems”, “a drop in gestation period and of calf weight”, “high fevers in the absence of an illness” “a rise in digestive problems like indigestion or diarrhoea” and even “lesions on the udders”, which form at the point where the injections have been given and sometimes cause tissue death…Lastly, one of the most deplorable side effects occurs in the event that the Posilac treatment is stopped, because it acts like a drug, and when the supply is interrupted a cow can display withdrawal symptoms that can lead to death, something which has earned Posilac the nickname of “crack for cows”.
In the US a freephone number has been in place since 1994 to give farmers a chance to report problems they’ve had with using rGBH with their livestock. In a report detailing these problems, produced by Mark Kastel, we find accounts from: Martin Van Heel – 70 cows in Minnesota – who reports that he no longer knows what to do to help his animals which are suffering from mastitis and huge abscesses at the injection points; Al Core – 150 cows in Florida – states that his cows can no longer walk under the weight of enormous udders and that they are limping because of sores on their legs and hooves; what’s more, three treated cows had given birth to monstrous calves (legs beneath their heads or stomach outside the body); Jay Livingston – 200 cows in the State of New York – explains that he had to replace 50 cows – some of which met very nasty deaths – and that after having stopped the injections, he had the rest of the herd inseminated; 35 cows had given birth to twins, most of them in very poor condition.
In view of all these side effects, and their impact on both animals and consumers of the animal products, it is surprising that the Food and Drug Administration gave authorisation for rBGH to go on the market. This approval for Posilac seemed to be more of a measure of support for Monsanto, on the part of the FDA, than any expression of valid concern for consumer protection.
A cow under posilac treatment:
 Eliot MARSHALL, « Scientists endorse ban on antibiotics in feeds », Science, vol. 222, 11 novembre 1983, p. 601