When the rat mother is permanently removed from her litter at 14-15 days postnatally, weight loss in the pups routinely occurs. We now describe a method by which normal weight gain can be achieved at this age in the absence of the mother. Liquid flowing in a continuous stream down a glass surface in the home cage elicits spontaneous licking from the rat pups. If the liquid is a high fat milk formula, the rat pups maintain normal body weight. They do not maintain normal weight if low fat (bovine) milk is presented in this way or if the high fat milk formula is merely available in a reservoir on the cage floor.