1. As a result of the use of strains of perennial ryegrass and white clover and varying applications of artificial fertilisers, pastures differing widely in total annual and seasonal production have been established. 2. No differences in the thrift and productivity of ewes and lambs grazed continuously and. fed to appetite on the different pastures could be observed under a management system aimed at keeping the sward between about 1 and 4 inches in height at all times. 3. In particular, pastures containing white clover of high prussic-acid glucoside content showed no ill effects on thrift or production in ewes confined to these pastures for four years. 4. The more productive the pasture, the more pronounced were the seasonal variations in production and the greater were the problems of efficient pasture control. 5. It is postulated that criticism of these pastures on the grounds that they promote ill-thrift in stock has its genesis in a general inability to effect adequate control at all times.
