1. 1. G. W. Arnold, 1963 . The Diet of the Grazing Sheep . Ph. D. Thesis . Univ. London.
2. Selective grazing by sheep of two forage species at different stages of growth
3. 3. C. P. Mcmeekan, 1957 . Grazing management and animal production .Proc. 7th int. Grassld Congr. pp.146 -56 .
4. 4. F. L. Milthorpe, and J. L. Davidson, 1966 . Physiological aspects of regrowth following defoliation .Proc. 12th Easter School, Univ. Nottingham, pp.241 -53 .
5. 5. R. W. Morris, 1965 . Private communication.