2.—(1) The following samples are to be taken from each flock of four week-old birds and each flock two weeks before it comes into lay or moves to the laying phase or laying unit–
(a)a minimum of two pairs of boot swabs; or
(b)a composite faeces sample.
(2) In this paragraph, “a composite faeces sample” means a sample of faeces consisting of a number of individual samples calculated in accordance with the following, each of which weighs not less than 1 gram and is taken from a site selected at random to represent the building or group of buildings in the holding from which it is taken.