Abstract: A valve arrangement includes a valve shaft having a fluid flow bore, and valve gear projections or teeth projecting from the valve shaft, constructed and arranged to receive a force to rotate the valve shaft. The valve arrangement can be used in a filter assembly having cartridge projections such as gear teeth to mesh with the teeth on the valve gear.

Abstract: An intraruminal device for controlled release of a drug formulation in the rumen of an animal, comprises an open-ended tube for containing the drug formulation, a piston adapted to travel longitudinally within the tube and biased so as to deliver the drug formulation through the open end of the tube. Travelling with the piston is an associated weight adapted to retain the device within the rumen during delivery of the drug formulation.

Abstract: A bolus for releasing a biologically active substance into a liquid environment according to this invention comprising an elongate core, at least one end of which is frustoconical and a liquid impervious casing at one end and open at the other disposed about the core, the bolus being so constructed that, in use, the casing is progressively shed as the core retreats, thereby releasing the active substance at a rate which varies over at least one time period, the casing being so structured as to retain its integrity without disintegrating in the absence of any support provided by the core.

Abstract: An intraruminal device has hinged wings (6) which lie along the body of the device during administration to the animal but which are urged outwardly by a spring (14) acting on a piston (12) shortly thereafter. The wings (6) are locked in the extended position: the piston (12) prevents them returning to the starting position, and T-bars (10) prevent them continuing to an "arms-over-head" position.The locking means may comprise a latch. The spring (14) may be replaced by a water-swellable polymer which expands on contact with rumen fluids.The device is used to administer drugs or minerals to the rumen of a ruminant over a prolonged period.

Abstract: A heavy density depot for lodgement in the remeno-reticulum of a ruminant animal and progressive release of veterinary substance, comprises an elongate body containing the veterinary substance and having an aperture to allow its progressive release, and a domed weight at a leading end of the body to facilitate passage down the animal's oesophagus. The weight is usually outside the body. The construction is particularly compact so maximizing the amount of veterinary substance contained.

Abstract: A bolus for administering a biologically active material for example an insecticide into a liquid environment such as the water of a reservoir or lake or an anthelmintic into the rumen juices of an animal comprises a succession of liquid impermeable outer segments (153, 263) enclosing a core which in the simplest case may be a single unitary active material segment (151, FIG. 14) or in a developed embodiment may comprise a succession of annular segments (269, FIG. 25) contained in sealed recesses (267) in the outer segments (263) which are located on a degradable central rod (265) e.g. of magnesium alloy, which itself will be active for instance to combat magnesium deficiency.As shown in FIG. 25, the device may incorporate a weight (275) which, in animal use, inhibits regurgitation.