A method for determining a mixing regime under which ingredients of a set of ingredients are to be mixed in the preparation of animal feed, characterised in that the method comprises: reading the ingredients from the set of ingredients, obtaining standard mixing periods for at least some of the respective ingredients of the set thereof from a master table (24,50,60) comprising a list of ingredients or categories of ingredients suitable for use in the preparation of animal feeds cross-referenced with corresponding standard mixing periods, identifying any non-standard conditions identifiable from the read set of ingredients, in response to a non-standard condition being identified, obtaining a mixing factor from mixing factors cross-referenced with at least some of the ingredients or categories of ingredients in the master table (24,50,60), for altering the standard mixing period obtained for a corresponding one of the ingredients of the set of ingredients to compensate for the identified non-standard condition, determining the mixing periods to which the at least some of the ingredients of the set thereof are to be subjected during a mixing cycle of the mixing regime as a function of the corresponding standard mixing periods and any corresponding identified mixing factors, and producing a loading sequence of the mixing regime in which the ingredients of the set of ingredients are to be loaded into mixing apparatus during the mixing cycle for mixing thereof to produce the animal feed, so that the ingredients for which mixing periods are determined are subjected to mixing for the corresponding determined mixing periods during mixing of the set of ingredients under the mixing regime. reading the ingredients from the set of ingredients, obtaining standard mixing periods for at least some of the respective ingredients of the set thereof from a master table (24,50,60) comprising a list of ingredients or categories of ingredients suitable for use in the preparation of animal feeds cross-referenced with corresponding standard mixing periods, identifying any non-standard conditions identifiable from the read set of ingredients, in response to a non-standard condition being identified, obtaining a mixing factor from mixing factors cross-referenced with at least some of the ingredients or categories of ingredients in the master table (24,50,60), for altering the standard mixing period obtained for a corresponding one of the ingredients of the set of ingredients to compensate for the identified non-standard condition, determining the mixing periods to which the at least some of the ingredients of the set thereof are to be subjected during a mixing cycle of the mixing regime as a function of the corresponding standard mixing periods and any corresponding identified mixing factors, and producing a loading sequence of the mixing regime in which the ingredients of the set of ingredients are to be loaded into mixing apparatus during the mixing cycle for mixing thereof to produce the animal feed, so that the ingredients for which mixing periods are determined are subjected to mixing for the corresponding determined mixing periods during mixing of the set of ingredients under the mixing regime.