By Brad HaireUniversity of GeorgiaThe dairy herd on the University of Georgia campus in Tifton, Ga., ate 12 tons of food Thanksgiving Day. They made a lot of noise but uttered no words of thanks. They simply ate their fill and walked away, expecting another meal just like it tomorrow.”Cows like the same diet every day,” said John Bernard, a livestock nutritionist with the UGA College of Agricultural and Environmental Sciences.”They don’t like a lot of change,” he said. “If you mix it up, it may take them several days to adjust, and their milk production can suffer.”The 230-cow dairy herd is about the size of the average commercial herd in Georgia. It’s used to test new feed additives, mixes and techniques the dairy industry can use to efficiently produce milk, Bernard said.”We basically want to find ways to make more milk and keep cows healthier,” he said.Although cows don’t like change, he said, they have changed over time. The United States had 21 million dairy cows in 1924. The average cow produced 476 gallons of milk, or 4,100 pounds, that year. (Milk is sold in pounds. A gallon weighs 8.6 pounds.)The U.S. had 9 million dairy cows last year. On average, each cow gave 19,995 pounds (2,325 gallons) of milk for the year. Georgia had 77,000 dairy cows in 2006.”We’re not dealing with the same cow from a few decades ago,” Bernard said. “Today’s dairy cow is like a top-notch athlete. You can’t just work up a routine and walk away. It changes.”Other things have changed more recently, he said. It costs dairymen 30 percent more than just a few years ago to feed cows. This is due to higher fuel and crop prices. It costs $5.80 per day to feed each UGA dairy cow.A dairy cow’s diet is mostly corn silage and hay. But it also includes vitamins, protein supplements and by-products such as the cottonseed left after cotton ginning and the grain mash left after beer, whiskey and ethanol production.”We look at how these by-products can fit into feeding,” he said. “What are the nutritional characteristics? Are they harmful at any level? We can then give the industry guidelines.”Dairy farmers can’t worry only about what goes in the front end, either. They must now be responsible for what comes out of the back end of a cow, Bernard said. Nutrients in cow manure can become pollution. What a cow eats can determine the nutrients it releases into the environment.In many ways, cows are excellent recyclers, he said. A cow has one stomach with four chambers, where microbes help it digest things humans can’t or won’t. “A cow is able to convert many by-products that would otherwise end up in landfills into energy for them and for us,” he said.The shopping list for the UGA dairy cows’ Thanksgiving Day meal was 554 pounds of alfalfa, 852 pounds of ryegrass, 12,572 pounds of corn silage, 1,100 pounds of cottonseed, 5,600 pounds of brewers’ grains, 2,000 pounds of corn and 1,658 pounds of minerals, vitamins and protein supplements.They washed it down with 30 to 40 gallons of water each.