DISTRIBUTION: Grows on different grains, e.g. maize and sorghum. Maize is produced mainly in the North-West, north-western, northern and eastern Free State, the Mpumalanga Highveld and the Kwazulu-Natal Midlands.
BOTANICAL DESCRIPTION:
General:
• A phytopathogen of especially maize which infests the cobs during the
silking stage.
• If the weather is rainy and the ears of corn are maturing in late summer and
early autumn, F. graminearum may infect only a few to a third of the kernels.
• Whatever amount of the ear is infected, all the kernels in that portion becomes
heavily infected and decayed by the fungus. It manifests as a pink cob rot
progressing from the tip to the base of the cob.
• Alternating moderate to low temperatures favour growth and toxin production.
• There are many types of cob rot and identification is not straightforward.
TOXIC PRINCIPLE:
Zearalenone metabolised to zearalenol. Relatively heat stable.
MECHANISM OF ACTION:
Binds to intracellular oestrogen receptor.
SYNDROMES:
Hyperoestrogenism.
SYSTEMS AFFECTED:
Urogenital system.
CLINICAL SIGNS:
• Latent period 5 - 8 days.
• Recovery about 7 days after withdrawal of contaminated food.
• Frank oestrogenism.
• Only pigs affected in S.A.
Female:
• Seen especially in prepubertal gilts
• Swollen vulva, slight turbid discharge
• Development of mammary glands
• Prolapse of vagina and rectum
• Sterility of sows, smaller litter size, agalactia.
Male:
• Development of mammary glands
• Swollen prepuce
• Atrophy of testicles
• Decreased libido.
NECROPSY:
Usually not fatal.
DIAGNOSIS:
Characeristic syndrome in large number of pigs. Send feed specimen to laboratory for chemical determination of zearalenone content.
TREATMENT: Withdraw contaminated feed. Avoid storage of high moisture grain on cob in open cribs.
