The Hormonal Cow

Ross Hume Hall, Ph.D.
biochemistry, nutrition,  food technology.

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Quality Ranking of Food Products
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The Hormonal Cow
Gene-Modified Crops
Prostate Cancer
Memory Loss
Supplement or Not





The milk cow has become a machine. Bred to pour out milk  by the ton, the super-efficient cow is nothing more than an object to turn grain into milk. The bovine growth hormone represents the latest wrinkle to get more milk. It revs even further an already revved up milk machine.

But is Her Milk Super Nutritious?

Our friend Ron Beresford, has established a new business, paring down hooves of milk cows. He tows a cow-size portable table to dairy farms all over the state. The hydraulic table pinions a cow and flips her on to her side. Ron then goes to work shaving down the animal’s hooves.

Here’s a bit of trivia you might not know. A cow's hooves, like your finger and toe nails, continually grow. Normally the cow doesn't mind because walking the pasture naturally wears down the hooves. But dairy cows are now tethered 24 hours a day in sheds, standing on unforgiving concrete.. They never move. If the hooves were not pared, the feet would become so painful the animal would topple over.

Cows like humans need to move around to maintain a balanced physiology. You thus have to wonder about the nutritional quality of milk produced by stationary cows. It is not a question the dairy industry asks. Nor, for that matter, do nutritionists raise the issue. To them milk is milk.

Occasionally the public does wonders about milk quality. A fierce argument has erupted over the quality and safety of milk produced by cows injected with bovine growth hormone (BGH). The hormone also goes under the name bovine somatotropin hormone (BST) and sometimes you see the term written rBGH. The "r" refers to the fact the hormone is genetically engineered.

Allowed in the United States, the hormone is banned in Canada. The hormone works like the after burner on a jet aircraft. It boosts  milk production in an already revved up animal.

While advent of the bovine growth hormone raises troubling issues, the hormone represents one more technique, like 24-hour tethering, applied in the name of efficiency. Efficiency in this case is a factory definition--maximized output per unit machine. The dairy factory has two goals: 1) convert feed as cheaply as possible into milk, and 2) get as much milk as possible per unit cow.

Cows are treated like production machines. A slight problem. A cow is not a machine but rather a living creature subject to the laws of nature. The modern dairy producer pushes those laws to the edge--over the edge some would claim-- trying to maximize production without killing the animal.

The Dairy Machine

The dairy machine starts with breeding. The milk cow has been bred specifically for producing milk. Unlike its muscular beef cousin, the bony milk cow is large-framed and drags a huge udder.

Hundreds of breeds of cows once existed, but dairy producers opted for those breeds that produce milk by the barrel, the more the better. After all, milk is sold by the volume, regardless of the milk’s nutrition. Producers have concentrated on few breeds. About 90 percent of American dairy cows consists of one breed, the Holstein-Friesian, those familiar black and white cows.

Long before cloning became a technical possibility, the dairy folk exploited ways to homogenize their herds. Cows are artificially inseminated. A single prize bull, son of a genetic line of high-production cows, donates enough semen in a lifetime to sire 500,000 calves.

What about the offspring of prize cows? A dairy cow following the laws of nature bears one calf a year--with a 50 percent chance it’ll be a useless male. To get around this limit, dairy producers surgically remove her eggs, fertilize them in a test tube, and implant the embryos in a fleet of cheap surrogate cows. A single, prize egg donor can be the biological mother of dozens of calves.

Cloning, still in its infancy, is fast becoming a commercial technology. This technique reproduces a calf with the exact genetic make up of the donor "mother". If mom produces10 tons of milk a year (a high yield), so will her cloned daughter.

Between using a small number of prize bulls and surrogate mothers, dairy producers have narrowed considerably the genetic variety in their dairy herds. With cloning, an already narrowed gene base could collapse into a blueprint for a single, cookie-cutter milk machine.

Feed to Milk

Nature designed cows with huge, multiple stomachs so they could eat grass. Grass is all they need. Dairy producers found, however, if they fed animals a diet of high-protein grain, milk production jumps.

In the modern dairy barn, when a cow is milked, a sensor reads an identity tag clipped in her ear. A computer analyzes the cow’s recent production record and feed consumption and triggers a feed dispenser. A bolus of mixed grains whose composition has been tweaked to match the cow’s inner physiology of the day drops in front of her nose. The cow munches while being milked.

The cow’s grain-based food, unnatural for a ruminant, pumps up her physiology and pumps out the milk. A stressed physiology, however, is susceptible to infection and cows have to be treated with a variety of antibiotics and other drugs. There is always a worry that drug residues will pass into the milk supply.

While dairy managers continually tweak the cow’s feed to maximize production, no one seems concerned about the milk these freak animals secrete. The chemical analysis for total protein and fat shows no great difference .But this is as far as nutritional analysis goes.

So if you ask about the effects on human consumers of the proteins flowing out of abnormal mammary cells, don’t expect an answer. The dairy industry has carefully nurtured the image: if it looks like milk and tastes like milk, it must be milk.

The Bovine Growth Hormone: Good for the Consumer?

The force-fed, stationary milk cow has become the norm in the dairy industry. My home state of Vermont has long projected a tourist image of rolling green fields dotted with black and white cows. But that image is fast vanishing as herds once pastured are locked n sheds. All the more work for our friend, Ron Beresford.

So as you see, long before the bovine growth hormone became an issue, the milk you buy in the supermarket is not the milk your grandparents drank as kids. So what about the safety of rBGH (approved in 1993 by the the Food and Drug Administration, FDA).

Animals, humans included, secrete a growth hormone, which causes the young to grow to adult size. Even the adult body needs the hormone to maintain tissue tone. The factory rBGH resembles but is not identical to the natural hormone the cow secretes.

From the point of view of milk production, the synthetic hormone works wonders. Injected into a cow, rBGH boosts milk production by 10-15 percent. Thus, a cow, producing 40 quarts a day, now produces an extra 4-6 quarts. But extra production comes at a cost and here in lies a storm of controversy.

In fact, the United States is the only country that has approved use of the synthetic bovine growth hormone, rBGH, in dairy herds. Australia and New Zealand have banned it and the countries of the European Union have declared a moratorium on its use. The Canadian government in 1999 refused to approve the use of rBGH, citing one reason for refusal, FDA’s own research on the safety of rBGH.

Canadian government scientists say the research FDA used to validate rBGH’s safety is deeply flawed. Moreover, in looking over dairy herds in the United States that use rBGH, the Canadian scientists were stunned to find:

cows have a 25 percent increased risk of udder infections
fertility has gone down 18 percent
lameness has shot up 50 percent

The Canadian government cites these facts as evidence the cow’s physiology, already stressed by flat-out production is stressed even more. FDA, rebuts this argument, saying the composition and wholesomeness of milk from rBGH cows matches the milk from non- rBGH cows.

No Long-Term Studies

It is easy to make such a statement when long term experiments haven’t been done. No one knows for sure what the long-term effect on young kids drinking rBGH-milk will be when they get older. A hint of possible bad effects comes from studies on milk protein, called insulin-dependent growth factor 1, IGF-1. RBGH cows product an abnormal amount.

Two, on-going Harvard studies, the physician’s health study and the nurses health study, found a link between IGF-1 and increased risk of breast and prostate cancer. How serious a risk remains to be seen, but critics of the use of rBGH, like Marion Nestle, director of the Department of Nutrition, New York University, call for more testing .

The American Medical Association has weighed in with the comment that the science on the effects of oral ingestion of IGF-1 is incomplete. In short, we don’t know enough about the safety of drinking milk produced in cows injected with rBGH

How does this controversy affect consumers of dairy products and what can you do about it? As of 1998, 30 percent of the United States nine million dairy cows are in herds that use rBGH. Milk, trucked to a commercial dairy from different farms, is mixed. Thus, you have to assume that all the milk in your local grocery contains a portion produced in rBGH cows. You won’t know for sure because the government doesn’t require milk from rBGH cows to be labeled as such.


Dairies that sell milk from cows that are not injected with the hormone can state that fact on the label. So in terms of overall nutritional quality, organically produced, hormone-free milk occupies  first rank on a quality scale.

Why organic. A concern over rBGH, drug use and pesticides sprayed on crops fed to cows causes many consumers to seek organic milk. Farmers have obliged and in most areas of the country you find organically produced milk and milk products. At one time you found them only in natural food stores. But mainstream supermarkets now sell organic milk products.

A final note: the controversy over rBGH ought to be expanded to include the overall issues of factory-bred and factory-run milk cows. In the broader scheme, the rBGH issue, while important, may not be the most significant problem with modern milk.

© 2001, Ross Hume Hall. All rights reserved
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