A 110-sow intensive piggery experienced a sudden drop in production. This first became apparent as an agalactia with subsequent piglet deaths. Investigations showed that this was a primary agalactia resulting from a lack of mammary development which, together with a reduction in birth weights, led to the loss of several litters. Toxin intake via one or more batches of feed was suspected. The feed source was changed, whereupon the syndrome disappeared. Chromatographic analysis revealed no known toxins but the clinical signs indicated the influence of a toxin.