I read Prof. Tom Zelman's review of the book "Cowed" by Denis Hayes and Gail Boyer Hayes in the March 15 Variety section with frustration. It appears that the book and certainly Zelman have trotted out the long and oft-heard polemics regarding cows in America. I feel it's critical to respond to repeated misinformation.

There are certainly important issues facing beef and dairy production, or for that matter all food production on our planet. The issue of the production of beef and milk is a complex one and does not reduce itself to tidy little dictums like "eat less meat." Let's consider a couple of the review's factoids.

Climate change: Cows burp up methane as a product of their digestive process. So do all ruminants (deer, bison, goats, sheep, yaks, etc.). But are cows the cause of global climate change? Absolutely not. There were roughly 70 million to 80 million bison in North America before European colonization. Those bison produced more methane than the average cow, since bison are bigger and eat an all-grass diet. Over a couple of centuries, humans replaced the bison with roughly the same number of cattle, but fed a diet that generates less methane.

Methane in the atmosphere gradually and naturally breaks down over about 20 years, so the methane that cows made 20 years ago is gone and is being replaced by cows today, making the levels of methane in the atmosphere from cows essentially stable.

These facts show that methane produced by cows in North America has had no appreciable effect on climate change. In fact, the amount of greenhouse gas produced per gallon of milk has dropped steadily over the past 50 years, due mostly to increased milk production per cow. People who continue to blame climate change on methane from cows are ignoring the facts.

Milk residues: Quoting from the review: "antibiotic-infused meat/milk goes into you." This is not true. When dairy farmers treat a milking cow with antibiotics (because she is sick; don't you agree she deserves treatment?), there are rules set by the federal Food and Drug Administration (FDA) that specify that the milk from the treated cow must be thrown away until the antibiotic clears from the cow. Every milk shipment is tested on arrival at the milk plant for the most common antibiotics used in dairy cows. If the shipment is contaminated, it is destroyed and the farmer must pay for the total tanker full.

From October 2013 through September 2014, 3.15 million shipments were tested in the U.S. Of those, only 429 were found to be positive for one of the antibiotics commonly used to treat sick dairy cows. The FDA just released a report on a targeted study of milk that looked for a broader range of drugs. A very few cases showed traces of less commonly used drugs. Regarding these newest targeted testing results, Dr. William Flynn, the deputy director for science policy in the FDA's Center for Veterinary Medicine, is quoted as saying: "These are encouraging findings. The low number of violations indicates that things are working well." These residues, although rare, are of concern, and professionals in the dairy industry will continue to work toward a zero tolerance. Finally, in 2014, the FDA tested more than 37,000 samples of retail-ready milk, cream, sour cream and yogurt. Not one — that's right, zero — tested positive for traces of antibiotics. So, no, your dairy products are not "infused" with antibiotics.

I, too, have a "genuine affection" for cows and have devoted my life to dairy cows and dairy farms. I have been doing so for nearly 40 years, and am absolutely certain that I have seen more dairy farms and dairy cows than either of the Hayes or Prof. Zelman. My experience shows me that the real truth is that dairy farmers care deeply about their cows. The care of cows is very good and gets better all the time. The milk produced is the safest, most regulated and inspected and wholesome food we consume.

John Fetrow is a professor of dairy medicine at the University of Minnesota's College of Veterinary Medicine.