Bulls only screw the cows once a year

A female reporter was conducting an interview with a farmer about Mad Cow Disease. "Mr. Brown, do you have any idea what might be the cause of the disease?"

"Sure. Do you know the bulls only screw the cows once a year?"

"Umm, sir, that is a new piece of information, but what's the relationship between this and Mad Cow?"

"And did you know we milk the cows twice a day?"

"Mr. Brown, that's interesting, but, what's the point?"

"Lady, the point is this: if I'm playing with your tits twice a day, but only screwing you once a year, wouldn't you go mad, too?"