Considering the fact, that livestock is nowadays likely.to be kept in
artificial or glass-filtered light during lifetime, the influence of e
xposure to UV- and redlight was tested on the average daily weight gai
n of post weaning calves. A significant increase in daily weight gains
was found from an exposure of more than 1 h on. This shows, that as f
ar as the deprivation of daylight is concerned, the keeping in natural
conditions is also of economical advantage.