To identify the effect of a sudden change in feeding of three forages with different contents of crude protein and fiber fractions on behavioral pattern of sheep, alfalfa hay, oats hay and perennial ryegrass hay were given to 6 animals with different sequences of feeding orders. The proximate chemical composition showed that oats hay and perennial ryegrass hay contained about the same level of crude protein and alfalfa hay more than 3 times of them. The dry-matter intake was the highest on the feeding of alfalfa hay and the lowest on that of perennial ryegrass hay with oats hay in the middle. The feeding of the previous hay affected the level of intake of the different kinds of hay followed. The change in the hay of greater difference in its quality appeared to have some psychological effects on sheep. (author abst.)