An account is given of experimental work carried out at Jealott's Hill on bloat.

Bloat was produced in dairy cows and sheep by dosing with lucerne juice. Sheep proved convenient test animals and were used in most of the tests described.

Parenteral and intravenous administration of the flavone quercetin, which inhibits the activity of smooth muscle, did not cause bloat even in the presence of cyanide. It is unlikely that flavones are concerned in bloat.

Fractionation of bloat-provoking lucerne juice showed that activity was retained after (a) precipitation of chloroplastic material, and (b) passage of clear juice through an anion or cation exchange resin. This suggests that the bloat-provoking factor is non-ionic and not adsorbed on resins—properties shown by saponinis.

Dosing sheep with lucerne saponins, four other saponins, egg albumin and a synthetic foaming compound failed to produce bloat.

Two household detergents and a number of surface-active agents did not relieve bloat, but foam-breaking compounds were very effective.

A synthetic inorganic saliva and cow's saliva did not prevent bloat in sheep and from the single test made with cow's saliva it is not possible to say if it increased the severity of bloat.

It is concluded that the formation of a stable foam is a major factor in lucerne bloat and that food constituents, other than saponins, and the physical condition of the rumen ingesta probably influence the stability of the foam.