A feed for domestic fowls which comprises a galacto-oligosaccharide composition which is prepared by heat-treating lactose in the presence of a mineral acid; or by adding an inorganic acid to lactose and then heat-treating the resulting mixture using an extruder. The feed serves to inhibit the formation of fatty liver, to improve the meat quality and the rate of egg laying, to improve the eggshell strength and to reduce the cholesterol content in the egg.
