“…Over the past twenty years, many studies comparing conventional (naturally faunated) animals with protozoa-free (ciliate-free) animals have been carried out. However, no definite conclusions have been drawn on ciliates because of the contradictory results obtained on growing animals (Bryant and Small, 1960 ;Eadie, 1962 ;Abou Akkada and El Shazly, 1964 ; Christiansen, Kawashima and Burroughs, 1965 ;Borhami et al, 1967 ;Chalmers et al, 1968) and on feed digestion (Abou Akkada andEl Shazly,1964,1965 ;Barringer, Trenkle and Burroughs, 1966 ; Klopfenstein, Purser and Tyznik, 1966 ;Luther, Trenkle and Burroughs, 1966 ;Kurihara et al, 1968 ;Males and Purser, 1970 ;ltabashi and Kandatsu, 1975 ;Jouany, 1975). Ciliates have shown wide differences in their effects in vitro on carbohydrate metabolism (Abou Akkada, 1965 ;Hungate, 1966 ;Church, 1975 ;Clarke, 1977).…”