Controversy exists in the literature concerning the validity of the nylon bag technique for investigating the nutritive value of feeds (Pidgen, Balch & Graham, 1980; Marten, 1981). Avariety of factors have been implicated in affecting results such as sample size, fineness of grinding and positioning of bags in the rumen. In addition basal ration has been shown to affect results (Lindberg, 1981 a, b; Siddons & Paradine, 1981). ørskov & Hovell (1978) showed that rate of digestion of hay in nylon bags was faster when the animals were fed on Pangola (Digitaria decumbena) hay rather than on sugar cane with its high sucrose content. In further work Ganev, ørskov & Smart (1979) reported that vegetable proteins degraded at a faster rate when incubated in nylon bags in sheep receiving dried grass rather than whole barley as their basal ration.