(1) The cat TV program Meow TV features squirrels running up and down trees to fast-paced music. DOG TV, on the other hand, shows three kinds of programs: calming, stimulating, and good behavior reinforcement. All their programs use the colors and sounds that dogs can see and hear. The idea is to keep dogs calm and occupied when their owners have to leave them home alone. (2) Dogs and cats in America are not the only animals being exposed to television these days. On a Russian dairy farm near Moscow, the cows are watching TV. Farm workers installed six large plasma screens in the cow farm. Then they selected 20 cows for an experiment. They divided them into two equal groups. There is no special channel or program designed for cows, so the farmer showed non-stop videos of beautiful, green grassy meadows and landscapes to the first group. The other group got only the background music without the video. After a month, the cows that were watching television produced on average three liters more milk than those that were not. Veterinarians say the images relax the cows and put them in a good mood for milking.
According to Paragraph (2), why did the one group of cows give more milk?