Copper sulphate and copper sulphide (CuS) as supplements for growing pigs.

The growth-promoting effect of the addition of 0.1 % copper sulphate (supplying 250 p.p.m. copper) to a growing-pig diet, reported by Barber, Braude, Mitchell & Cassidy (1955), has since been widely confirmed. The mode of action of Cu is unknown, and whether the site of action is enteric, systemic or both remains obscure. In an attempt to throw some light on this problem, a study was made of the effect of supplementing a growing-pig diet with a relatively insoluble Cu salt, as compared with that of the highly soluble copper sulphate. The present paper gives the results of two experiments in which dietary supplements of Cu were given either as the sulphate or as the sulphide. The results of a preliminary investigation of the number of fungi that could be cultured from samples of faeces taken at intervals from all pigs in the first experiment are also included.