Part 2 of mycotoxins in swine feed: Zearalenone

What you don’t want in your pig feed. This series talks about two of the major mycotoxins affecting the northern United States and a part on how to alleviate their effects in the feed.

map of US showing Zeralenone results by state
Figure 3 Zearalenone results from May 2018 (Adapted from Biomin)


Zearalenone is produced by Fusarium graninerarum and F. culmorum. Other names for this mycotoxin are F2 toxin, FES (fermentation estrogenic substance), and RAL (resocyclic acid lactone); (Zinedine et al., 2006). The mold is most prevalent in the Midwest region of the United States, mostly affecting corn, wheat, sorghum, barley, and rye (Zollner et al., 2002). The mold germinates with moisture levels above 20% and temperatures within 65 up to 85°F. Most of the growth occurs when grain is stored with high moisture content. The affected grain will be white-reddish color on the plant ear or head blight, which makes it relatively easy to detect. Zearalenone is found to be relatively stable in heat conditions. While the mold can with stand high heat conditions, growth most efficiently in moist and cooler conditions. 

            Zearalenone affects the reproductive system of pigs. This toxin is responsible for vulvovaginitis and estrogenic syndrome that affects any stage of reproductively active swine (Harwig et al., 1975). Symptoms that are commonly observed in gilts are swelling and edema of the vulva, followed by enlargement of the uterus with proliferation of epithelium and myometrium and atrophy of the ovaries. In young boars’ mammary glands may develop hyperplasia and testicular atrophy can occur (Fink-Gremmels and Makelinejad, 2007).

Signs of Zearalenone effect on Pigs



Irregular estrus cycle

Vulva reddening

Reduced birth size of piglet

Vulva swelling

Vaginal or rectal prolapse

Ceased embryo development

Increase number of mummies

Table adapted from Fink-Gremmels an Makelinejad, 2007

            Levels for zearalenone are 0.1 mg/kg for nursery pigs and gilts and 0.25 mg/kg for sows and finisher pigs (Tiemann and Danicke, 2007). Studies have shown for a 60-pound gilt to have 1 mg daily of zearalenone have produced a swollen vulva within 5 days at initial intake.

Did you find this article useful?