Field outbreaks of hyperoestrogenism (vulvo-vaginitis) in pigs consuming maize infected by Fusarium graminearum and contaminated with zearalenone.

Abstract

During the spring and summer of 1979 field outbreaks of porcine hyperoestrogenism characterized by swelling and reddening of the vulva and teats in prepubertal gilts and enlargement of the mammae in young males occurred in the mistbelt of the Natal Midlands. On a farm in the Ixopo district, pigs were fed a mixed ratio containing home-grown yellow maize stored on the cob in a crib and all the young pigs with a mass of 25-85 kg (=a total of 350) were affected. Maize ears from the crib had a high percentage (91%) of kernels infected by Fusarium graminearum and contained 10 mg/kg of zearalenone. The mixed ration contained 0,95 mg/kg zearalenone. After dilution of the contaminated maize with good quality white maize, a dramatic decrease in both the incidence and severity of clinical signs occurred within 3-4 days. On a farm in the Winterton district, approximately 80% of the growing pigs with a mass of more than 40 kg fed a mixed ration containing shelled yellow maize from the silo of the local Agricultural Co-operative were affected. The incidence as well as the severity of the swelling of the vulvas and/or treats were lower than on the farm at Ixopo, thus indicating a lower level of oestrogen intake. A sample of maize from the silo delivered to this farm contained only 0,06 mg/kg zearalenone while the mixed ration did not contain chemically detectable levels of zearalenone. This is the first published record of field outbreaks of porcine hyperoestrogenism associated with the ingestion of F. graminearum infected maize contaminated with zearalenone in the Republic of South Africa.