THE COW
(a living machine) The production of ice cream can't even begin without a pure supply of milk, and the machines that produce the milk are purely amazing -- because they're living machines. A dairy cow might not look like much of a machine on the outside, but inside there's a complex series of milk-making mechanisms hard at work, 24 hours a day.

In order to produce milk, the cow has to gather and then process all the raw materials that are necessary for milk-making. These materials are complex carbohydrates, cellulose, proteins, vitamins, and water. Good pasture grass and some grains will provide all of these foods. Unlike the other machines in the ice cream manufacturing process, the cow can gather these items for herself. Quite simply, she needs to chow down -- a lot!

The first step in the process is for the cow to grind the hay and grain so that they can be efficiently digested. To do this, the cow wraps her tongue around the grass and pulls it into her mouth. Her jaw has the ability to move from side to side while her tongue keeps the hay between her broad, flat, grinding teeth. Next she performs a chemical reaction on the hay. She adds a liquid called saliva, which plays a very important part in the digestive process. Saliva contains the enzyme ptyalin, which is used to break down starches into simple sugars. Saliva has a pH that ranges from neutral to slightly alkaline. In other words, her mouth is "sweet" rather than acidic. This means that any microorganisms that happen to be on the hay are not killed. This is good news for the cow because she needs the microorganisms in order to complete the digestive process.

As the chewing and grinding continues, a little ball of ground hay called a bolus is formed. The cow coats the bolus with mucin, a natural lubricant, also found in saliva. Mucin allows the bolus to be easily swallowed and passed to the next organ in the process, the rumen.

Check out the interactive version on the B&J Website if the link still works

With all that eating and chewing and grinding going on practically all the time, you'd think the cow would have to have a pretty big stomach to hold it all. Well, she does, but a cow's stomach is actually 4 stomachs -- each is like a separate chamber, or compartment, and each compartment plays a part in the milk production process.

The rumen, the large first compartment of the cow's stomach, is actually swimming with thousands of microorganisms, invisible to the human eye. These microorganisms break down the complex cellulose in grass, which the cow cannot do by herself. If it were not for these creatures breaking down the hay and grain, it would be very difficult for the cow to use them in the production of milk. Much of the hay and grain would simply pass right through the digestive system unused.

The microorganisms also get some help from the cow. These organisms don't have teeth, which means they can only digest the surface of the bolus of hay. Here is where the cow helps. Every so often, she will reverse the swallowing process and return the bolus to her mouth where she chews it again. This action exposes the undigested parts of the bolus for the organisms to digest the next time around. If you've ever wondered what it means when a cow is "chewing her cud", there's your answer! Both the cow and the organisms in her stomach benefit from this cooperative venture. The cow is able to utilize a food material more efficiently and thus produce more milk for her offspring. The microorganisms are given a warm, comfortable place in which to live and reproduce. They are also provided with a constant supply of food. This cooperation between two different organisms is known as a symbiotic relationship.

The last three chambers of the cow's stomach are called the reticulum, the omasum and the abomasum. These chambers contain a solution called hydrochloric acid. This acid allow the remaining food materials that could not be broken down in the rumen to be digested along with some microorganisms that are inadvertently pushed along in the process. Thus, the microorganisms give their lives for the production of milk.

The cow's intestine extracts any remaining nutrients from the hay while the waste product, manure, is deposited on the fields. (Oh, and by the way, even though you're probably thinking "Eeeewwww! Cow poop!", cow manure is an excellent fertilizer and helps to produce healthy and nutritious grass and clover crops.)

No milk yet, but we're getting there. The four stomachs and the intestine of the cow are covered with thousands of blood vessels. During the digestion process the liquid nutrients, which are chemically produced by the digestion process along with some liquid wastes, are transferred to the blood stream. First the wastes are filtered out of the blood by the kidney and expelled from the body (as "urea" -- yup, that's a scientific word for "cow-pee").

Finally, the nutrient-rich blood moves via the milk vein to the udder. As it passes through, special structures called mammary glands remove the nutrients, fat and other valuable life-sustaining elements and store them as milk in the udder itself. The milk is then removed from the udder either by a calf or the dairy farmer's milk machine. It is pasteurized at the St. Albans (VT) Dairy Co-op, and placed in huge stainless steel cooling tanks before being shipped to all three Ben & Jerry's ice cream factories in Vermont.

Next stop: The Blend Tank at the Ben & Jerry's Waterbury Factory.