Abstract: An intra-ruminal bolus and method of manufacture is described that releases a therapeutically effective amount of at least one beneficial agent to a ruminant animal over a time period of less than approximately 21 days. The bolus includes at least one beneficial agent, at least one densifier material, at least one binding agent, and at least one releasing agent. The bolus is manufactured using a ratio of binding agent to releasing agent that is tailored to achieve the desired rate of release and timing of delivery. This ratio is in the order of approximately 1 part binding agent to between approximately 0.01 and approximately 2 parts releasing agent and may be varied within this range in order to obtain the preferred release length of time. The bolus is particularly useful for delivery of anti-parasitic compounds but may also be used for delivery of other active agents such as trace elements including selenium and cobalt.

Abstract: A method of treating animals characterised by the step of introducing to the animal a single delivery device containing two or more active agents, wherein the delivery device is configured to release an effective amount of active agents over a defined time period of 3-14 days.

Abstract: The present invention relates to a delivery mechanism for the introduction of a biological agent to an animal characterised in that the delivery mechanism is a bolus which contains the biological agent. In preferred embodiments of the present invention the biological agent is Duddingtonia flagrans and the animal to which the mechanism is introduced is a sheep.

Abstract: The invention described is a bolus for the controlled release of a beneficial agent in the rumen of a ruminant animal. The bolus consists in a core containing a binder, solubilising agent, the beneficial agent to be released and, when required, a densifier. The core is coated with a wax coating, preferably with an opening exposing a small part of the core to rumen juices. The core is gradually dissolved releasing the beneficial agent. As the core dissolves the wax coating erodes until the bolus disappears completely.