My niece collects cows. Well, images of cows, anyway. And she’s not the only one. Apparently, cows are hot right now.
Personally, I’ve never been all that enamored of them. My encounters with cows have generally been unrewarding, from the time I tried to milk one (an experience neither of us enjoyed) to the time I helped a veterinarian chase them around a farmyard. Running around a farmyard after a bunch of cows isn’t my idea of a good time. You step in stuff.
However, I definitely do appreciate the other end products of cows, from milk to leather to steak, and so do most other humans. That’s why we’ve cultivated cattle for 8,500 years.
Cattle were domesticated in both Europe and Asia at about the same time. Europeans probably domesticated the now-extinct wild auroch, from which most of today’s dairy and meat-producing breeds descend, while Asians domesticated the zebu, characterized by a hump on the withers–i.e., the Brahman. As a result, European and Asian cattle are actually two different species.
After millennia of domestication, cattle from different regions developed noticeable differences, but most of our modern breeds were deliberately created over the last couple of centuries. Robert Bakewell of Dishley, England, who lived from 1725 to 1795, is considered the father of animal breeding. His four-part breeding plan was simple but effective: breed animals only for those traits that make them more useful; breed the best to the best; inbreed; and test-breed animals before adding them to the breeding program.
Today there are about 274 important recognized breeds, and many other variations that may eventually attain breed status. The goal is always to create cattle better suited for certain environmental conditions. Breeding is really just a slow but effective form of genetic engineering.
We expend so much effort on cattle because they boast an ability we don’t: they can digest cellulose, which makes up the cell walls of plants. When we eat cellulose, it serves only as “roughage,” or “fiber.” Herbivorous species, however, get nourishment out of cellulose. Cattle, sheep, goats, deer, antelope, chevrotains, camels and lamas all use a process called rumination, which is why these animals are called “ruminants.”
The stomach of a cow is divided into four parts. The first part, the rumen, contains bacteria and protozoa that break down cellulose into fatty acids and other compounds. The fatty acids and other nutrients enter the cow’s bloodstream directly from the rumen, and provide up to 70 percent of its energy.
This process, a form of fermentation, produces carbon dioxide and methane, which the cow belches out or, ahem, otherwise expels. These gases are major contributors to the greenhouse effect, and the number of cattle worldwide (estimated at more than 1.3 billion) make cow eructation and flatulence, silly as it sounds, a serious environmental concern. Researchers are beginning to develop food additives and drugs that can reduce cow-gas emissions.
Some coarse, fibrous material remains after this first step of digestion; it’s sent back up to the mouth as a small mass properly called a bolus but better known as a cud, to be chewed and re-swallowed. This time it passes into the second chamber, the reticulum, for further fermentation; then into the third chamber, or omasum, where most of the water it contains (mostly the cow’s own saliva) is re-absorbed. Finally it gets passed into the fourth chamber, the abomasum, or “true stomach,” where ordinary digestion occurs. Essentially cattle are walking agricultural factories, processing material unusable by us into meat and milk.
Cows have four mammary glands, each of which contain specialized cells that filter the constituents of milk from the bloodstream as it passes through the udder. Four hundred liters of blood have to pass through the udder for every liter of milk that’s produced. A typical cow can produce 18 kilograms of milk daily.
A milk cow only gives milk when it bears a calf, which it can only do about once a year; it produces milk for about 305 days. The average cow is good for about three lactations, although occasionally one will last for eight to 10. Generally, one fourth of a dairy herd has to be replaced each year.
Still, a dairy cow can get life insurance a lot easier than a beef cow can. Beef cattle are raised by their mothers for the first six to eight months; fed high-quality roughage or excellent pasture for the next six months to a year; fattened in a feedlot on high-concentrate rations for three to five months, gaining a kilogram a day; and then…it’s curtains.
Science and technology have had considerable impact on cattle-raising over the years. Artificial insemination, for example, allows genetically superior bulls to sire thousands of calves a year, by cows they’ve never even had the pleasure of mating–er, meeting. Similarly, top pedigreed cows can be injected with a hormone that causes multiple ovulation, the eggs artificially inseminated, and the resulting embryos withdrawn from the cow and implanted in other cows to be brought to term.
Protein, vitamins and minerals are regularly added to the diet of feedlot cattle, along with antibiotics to halt the spread of disease, to which animals crowded into a feedlot are much more susceptible than animals on the open range. However, some scientists have warned that these antibiotics could lead to drug-resistant bacteria which could find their way into meat and infect humans. Some outbreaks of salmonella have been linked to contaminated meat. The risks continue to be investigated.
Another highly controversial application of technology to cattle is the use of bovine somatotropin, BST, a bovine growth hormone. BST increases lactation in cows by up to 25 percent. Even though BST is a naturally occurring hormone which can already be found in milk, its use concerns some people, who worry about what it might do to humans. It may also put dairy cattle under greater stress, resulting in health problems.
Further technological advances are just around the corner. Cows may soon be genetically altered (modern methods are faster than traditional breeding) to produce “designer milk”–milk with just the right protein levels for use in cheese, for instance, or infant formulas. Cows could even be used to produce interferon or other medically useful substances along with their milk.
Amazing animals, cows. Perhaps I’ve misjudged them all these years…a crime which would make me terribly distraught if not for these words of advice from a young man wise beyond his years:
“Don’t have a cow, man.”
