This subject came up in another thread. I'm attempting to answer it here since I didn't want to highjack the other thread with an answer. The question was "why can you give chickens yogurt but not milk?" Here is the answer. Lactose intolerance is the inability to digest significant amounts of lactose, the major sugar found in milk. Lactose intolerance is caused by a shortage of the enzyme lactase, which is produced by the cells that line the small intestine. Lactase breaks down the milk sugar into two simpler forms of sugar called glucose and galactose, which are then absorbed into the bloodstream. Undigested lactose fermented by bacteria in the colon creates lactic acid and other fatty acids. Since the active cultures in yogurt (also known as probiotics) break down lactose naturally into lactase enzymes, there is no intolerance. I hope I didn't confuse anyone. If so just ask.