1. ARC (1965). The Nutrient Requirements of Farm Livestock, No. 2, Ruminants. Agricultural Research Council, London.
2. Bianca, W. (1965).Journal of Dairy Research,32, 291–345.
3. Crutchfield, W. D. (1968).Veterinary Medicine,63, 1141–1144.
4. NRC (1981). Effect of Environment on Nutrient Requirements of Domestic Animals. National Academy Press, Washington.
5. Randall, W. C. & McClure, W. (1949).Journal of Applied Physiology,2, 72–80.