Dairy farming has a notoriously harsh impact on the environment; according the the World Wildlife Fund for Nature, around 270 million cows produce milk for a growing world population that is subsisting on an increasingly western diet. As cows break down plant material in their gut for nutrition, a fermentation process is triggered and methane is released—which has at least 25 times the global warming potential of carbon dioxide. And in order for cows to produce dairy, they must first become pregnant—in the vast majority of cases this is done through an imprecise process of artificial insemination, which means breeding huge cattle herds in order to meet demand. To address this, one group of researchers from the University of Nottingham has proposed treating cows with hormones so as they breed faster, while younger, allowing for smaller herds with a lower impact on global warming. But their proposal has raised some eyebrows.
The research, which was recently published in PLoS ONE, simulated data for 10,000 herds of 200 cattle and predicted the daily possibility of conception from the start of the study up to day 300 of lactation, comparing traditional methods of insemination (done each time a cow is in heat), with targeted insemination triggered by the use of hormones. Specifically, they looked at the effects of Ovsynch, Ovsynch with progesterone, and Double prostaglandin.
The lead researcher, Dr Simon Archer from the University of Nottingham School of Veterinary Medicine and Sciences, found “Routine hormone treatments could improve efficiency by getting more cows pregnant sooner. This is better for the environment as for every litre of milk produced; fewer animals would be needed, which generates less waste.” More specifically, Dr. Archer explained in a statement, was that “[t]he results varied between herds, but for an ‘average’ UK herd, there would be a reduction in methane emissions equivalent to the global warming potential of two cars, a family home, or 21 barrels of oil. The farmer would also save at least £50 per cow each year in production costs.”
And that’s certainly nothing to sniff at, but for the fact that we already treat some herds with hormones to help cattle become more muscular to provide beefier beef. And these testosterone-like chemicals are excreted by the cattle, after which it washes away into groundwater and streams and lingers in the environment. Current dairy farming practices also increase the amount of natural hormones present in milk. Former Harvard fellow Ganmaa Davaasambuu explained in one talk that “[a]mong the routes of human exposure to estrogen, we are mostly concerned about cow’s milk, which contains considerable amounts of female sex hormones,” adding that modern dairy farms cows are milked for around 300 days per year, including while they are pregnant—and the later in pregnancy a cow is, the more hormones appear in their milk. A report in 2006 noted that “In a study of modern milk in Japan, Ganmaa found that it contained 10 times more progesterone, another hormone, than raw milk from Mongolia.”
So while amending farming techniques to create lower levels of methane emissions is of significant import, it’s likely that there will be significant scrutiny of any efforts to add more hormones to the process, or to the food chain. In the meantime, there are other options; namely, a widespread reduction in the consumption of animal products, as several studies have called for.