Farmer's Lung Disease: the Development of Antigens in Moulding Hay

SUMMARY: Antigens important in farmer’s lung disease (FLH antigen complex) developed in wet hay ( ⩾30 % water content) 4–6 days after baling; their development was associated with increases in pH value of the hay, in content of soluble and volatile nitrogen, and in numbers of actinomycetes, bacteria and fungi. Most of the antigens were common to the actinomycetes Thermopolyspora polyspora and Micromonospora vulgaris, but others were unidentified. Brown hay from a self-heated stack contained no FLH antigen except where actinomycetes and fungi had developed and the pH had risen from 4·5 to near 7·0.