The Impact of Mycotoxins on Pig Production Performance

Mycotoxins are toxic secondary metabolites produced by certain molds and are commonly found in poorly managed feed ingredients. These toxins can be generated at various stages, including growth in grain fields, harvesting, feed processing, storage, and transportation.

I. Mycotoxins and Their Hazards

　　In the actual management of pig farms, the hazards posed by mycotoxins are often overlooked. Very often, after a pig herd falls ill, the affected pigs show poor responses to various medications, and the mortality rate rises. The laboratory test results from quarantine agencies typically include diagnoses for diseases such as Eperythrozoonosis, swine fever, blue ear disease, and circovirus infection. We cannot deny the existence of these diseases; however, mycotoxin testing is generally not included in routine diagnostic panels. As a result, managers and technicians at large-scale pig farms tend not to consider mycotoxin issues at all. After the pigs fall ill and treatment proves ineffective, they seek advice from multiple experts, undergo testing by various institutions, and try one drug after another—even increasing the frequency of vaccine injections—but the mortality rate remains stubbornly high. After much trial and error, they finally realize that mycotoxins are the root cause of the problem.

　　Currently, the number of toxins detected in feed has exceeded 350. Among the mycotoxins, those that pose the greatest threat to pigs include: aflatoxin, zearalenone (F-2 toxin), vomitoxin, and ochratoxin.

　　There is a synergistic effect among various mycotoxins in feed. The combined action of several mycotoxins has more severe adverse effects on animal health and production performance than any single mycotoxin acting alone. Moreover, feed ingredients and complete feeds often contain multiple mycotoxins simultaneously, which can lead to more complex clinical symptoms when pigs are poisoned. This is particularly pronounced when bacterial or viral factors are also present. Consequently, diagnosing mycotoxin poisoning in pig herds caused by mixed infections involving multiple mycotoxins, bacteria, and viruses becomes increasingly challenging in clinical practice.

II. Main Symptoms of Mycotoxin Poisoning in Pigs

　　The most obvious symptom of zearalenone poisoning in pigs is persistent redness and swelling of the sow’s vulva. This is an important indicator for determining whether the condition is caused by zearalenone. Such redness and swelling is often mistaken for estrus in sows; however, sows exhibiting this symptom will not allow boars to mount them for mating.

　　The pig herd is consuming feed containing aflatoxins, vomitoxin, and T-2. When pigs are fed feed contaminated with one or more of the following toxins—mycotoxins such as zearalenone or ochratoxin—symptoms often include decreased appetite or refusal to eat, persistent elevation of body temperature, red spots appearing on the skin all over the body, water-soaked lesions on the scrotal skin, affected pigs assuming a dog-sitting posture, coughing, labored breathing, redness and swelling of the prepuce, joint swelling, stiffness in the limbs, necrosis of the hooves, persistent diarrhea or constipation, and in some cases, vomiting, rectal prolapse, or even vaginal prolapse. Sows may fail to come into heat, experience difficulties in mating, or suffer from abortion, stillbirths, weak piglets, or postpartum agalactia. In severe cases, individual pigs may develop paralysis.

　　Anatomical examination reveals symptoms such as pneumonia, gastritis, gastric ulcers, enteritis, and nephritis. Certain mycotoxins can directly cause pulmonary edema, leading to pneumonia—a major cause of acute death in affected pigs. Other lesions include lymph node enlargement and congestion, pleural effusion, pericardial effusion, yellow gelatinous deposits around the heart, gastric perforation, shedding of the gastric mucosa, thickening of the intestinal wall, blackened and putrefied contents within the intestines, bladder perforation, hepatic cirrhosis, yellow discoloration of subcutaneous fat, thinning of the blood with impaired coagulation, inflammation of the gallbladder, and necrotic lesions in the connective tissues near the anterior thoracic or mandibular lymph nodes, among others.

III. Main Symptoms of Mycotoxin Poisoning in Pigs at Different Stages

　　1 · Piglets: Piglets affected by poisoning often exhibit acute onset, with central nervous system symptoms such as head tilting to one side and resting their heads against the pigpen railing; they usually die within a few days.

　　2 Growth-and-fattening pigs: The disease course is relatively long. Typically, body temperature remains normal in the early stages, but appetite gradually declines; in later stages, appetite completely disappears, accompanied by abdominal pain, vomiting, diarrhea or constipation, and the presence of mucus and blood in the feces. These pigs become emaciated, with coarse and disheveled back hair. Redness appears on the face, ears, inner sides of the limbs, and abdomen, along with symptoms such as jaundice and anemia. Feed conversion efficiency decreases, and growth and development are delayed. Since mycotoxins can damage the immune system of pigs, causing immunosuppression and making the herd more susceptible to pathogen infections, recent research from overseas institutions has also revealed that mycotoxins are the primary cause of Porcine Dermatitis-Nephropathy Syndrome (PDNS) in pig herds.

　　3 Sows: When sows are poisoned by mycotoxins, particularly aflatoxins, they may exhibit jaundice of the skin, weakness in the limbs, normal body temperature, dry feces, rectal bleeding, and darkened urine—sometimes even a deep tea-colored hue (hemoglobinuria).

　　(1 ) Pregnant sows: Exhibiting increased rates of stillbirths, mummified fetuses, miscarriages, or neonatal piglet mortality, as well as abnormal estrus behavior after farrowing.

　　(2 ) Young sows: Feeding them with feed containing 0.1–0.15 ppm of zearalenone can cause redness and swelling of the vulva in young sows, as well as an increase in uterine volume and weight, manifesting as signs of estrus or impending farrowing.

　　(3 ) Lactating sows: Exhibiting gradual feed refusal, persistent estrus, or prolonged estrous cycles, which negatively affect the survival rate of piglets during the lactation period.

　　(4 ) When the mycotoxin content in feed exceeds 5 ppm, sows may experience rectal and vaginal prolapse.

　　4 Adult boar: Exhibits testicular atrophy.

　　If redness and swelling appear in the vulva of sows—especially growing sows—it can basically be confirmed as zearalenone poisoning. Various drug treatments prove ineffective, and relying solely on medication still results in a high mortality rate. Affected pigs stop eating compound feed and only consume green forage; however, laboratory testing of feed ingredients is still necessary for a definitive diagnosis.

IV. Prevention and Treatment

　　1 Prevention: The highest concentration of mycotoxins is typically found in corn flour containing broken grains and insect-damaged kernels. Therefore, it’s advisable to screen the corn flour thoroughly to remove these defective particles. Additionally, adding mycotoxin-binding agents to feed can help mitigate the risk. Many manufacturers claim that their products can adsorb mycotoxins from feed; however, conventional silicoaluminate or gel-based organic ketones—whether imported or domestically produced—have shown little to no real efficacy against vomitoxin, T-2 toxin, zearalenone, and ochratoxin. To effectively combat these mycotoxins, it’s essential to use mycotoxin-binding agents made from modified materials, such as Anbaitu.

　　2 Treatment: Immediately discontinue the use of all feed ingredients suspected of containing mycotoxins, especially corn. Currently, there is no specific antidote for mycotoxin poisoning in pigs. For severely ill pigs showing symptoms of pneumonia, administer antibiotics via intramuscular injection; treat the entire herd with antibiotics. Increase the supply of green feed. Strengthen management practices, and the treatment course should last approximately 15 days. Given liver and kidney damage, sulfonamide drugs are contraindicated; instead, use lomefloxacin, which has a favorable effect on the urinary system. Additionally, increase the levels of added compound vitamins, methionine, selenium, and folic acid in the feed.