WINTER BONUS MAGAZINE 2026

Zearalenone (ZEA) – effects on pigs Zearalenone (ZEA) is a non-steroidal oestrogenic mycotoxin. It occurs in maize, wheat, barley, and other cereals under cool and wet growing conditions. ZEA mimics the action of 17 β -oestradiol and disrupts the endocrine system. The ZEA molecule consists of a macrocyclic lactone ring, a resorcinol (benzene-1,3-diol) aromatic ring, and multiple hydroxyl (–OH) groups, which enables the mycotoxin to bind to oestrogen receptors (see figure 2). Impact on growth performance DON reduces feed intake of pigs, and this results in poor growth performance due to the DON molecule impairing protein synthesis and modifying gene expression. Combinedmycotoxin effects DON often co-occurs with ZEA, T-2, and Fumonisins, amplifying physiological stress and performance losses in pigs. Impairment of immune system Mycotoxins suppress the immune cell functions and modulate inflammatory pathways. This increases the pig’s susceptibility to secondary infections and diseases and may also reduce vaccine efficacy. Figure 2: ZEA molecular structure Negative effect on the gastro-intestinal tract DON is rapidly absorbed through the intestinal lining without going through any structural changes. This causes damage to the intestinal mucosa and impairs epithelial integrity. The toxin interferes with digestive enzyme activities and the intestinal barrier, causing reduced nutrient absorption and diarrhea. ZEA is chemically stable, resistant to heat and normal feed-processing conditions, which makes prevention and mycotoxin management critical. Reproductive and hormonal effects ZEA is an oestrogenic mycotoxin, affecting the reproductive system. It binds oestrogen receptors, leading to hormonal disruptions. This may cause reduced fertility, swelling of the vulva and mammary tissue, and irregular oestrus cycles. In boars it may reduce sperm quality and cause testicular atrophy. Winter 2026 BONUS www.agribonus.co.za 114