Diagnosis > Pig
Mycotoxins in pig production
The symptoms exhibited and the degree with which pigs are affected by mycotoxin toxicity, are largely affected by the kind of mycotoxin involved and their concentration in feed, as well as by the age and phase of production of the pig. Young pigs and breeding pigs are generally the most susceptible to mycotoxins.
In addition, combinations of certain mycotoxins may produce elevated negative effects on performance above that normally expected for each of the mycotoxin levels evaluated individually, and therefore must be considered. (Table 1)
Table 1. Maximum Tolerable Level of Mycotoxins Commonly Found in Pig Feeds
|Mycotoxin||Maximum tolerable level||Comments|
|Aflatoxins (B1, B2, G1, G2)||< 20 ppb for human use, dairy feed, feed for immature animals
< 100 ppb for breeding swine
< 200 ppb for finishing swine (>120 lbs body weight)
Acute signs: anorexia, depression, ataxia, epistaxis.
Chronic signs: reduced feed efficiency, reduced milk production, icterus, decreased appetite.
|Zearalenone||< 1 ppm for young growing pigs
< 2 ppm for breeding herd
< 3 ppm for finishing pigs and young and old boars.
|Oestrogenic effects. Swollen vulvas, vaginal or rectal prolapses in pre-pubertal gilts. Enlarged uterus, swollen or twisted uterus, shrunken ovaries. In boars, testes atrophy, enlarged mammary glands, decreased fertility.|
|Deoxynivalenol (vomitoxin)||< 5 ppm on grain and grain by-products. DON contaminated feedstuffs should not exceed 20% of the diet. (< 1 ppm in complete feeds)||Reduction in feed consumption and weight gain are inversely proportional to concentration of DON. High concentrations cause feed refusal and vomiting.|
|T-2 toxin||< 1 ppm||Potent immunosuppressive agent that directly affects immune cells and modifies immune response as a consequence of other tissue damage. Frequent defecation, vomiting, weight loss and feed refusal.|
< 5 ppm (extrapolated from horse data)
|Carcinogenic in laboratory tests using rats. Associated with pulmonary oedema in pigs.|
|Ochratoxin||< 200 ppb has been associated with kidney damage in swine||Ochratoxin A is most common and potent.
Reduction in growth, feed efficiency, increased mortality, liver and kidney damage.
|Ergot||< 200 ppb||Vertigo, staggers, convulsions, temporary posterior paralysis, eventual death. Decreased peripheral blood supply. Reduced growth, tail loss, reduced reproductive efficiency of sows.|
The development of novel feeding and housing systems has added a new dimension to mycotoxin control in pigs. Mycotoxin exposure can occur in both dry and wet feeding systems, especially the latter, with long distribution lines that are hard to clear. High welfare systems using straw bedding pose an additional risk and this is especially pertinent to the group-housing of sows. Mycotoxins suppress immune function in pigs and this may eventually decrease resistance to infectious diseases, re-activate chronic infections and/or reduce vaccine and therapeutic efficiency.
Common symptoms associated with mycotoxicosis include:
- Reduced feed intake
- Poorer growth rate
- Decreased feed conversion efficiency
- Increased incidence of disease
- Reduced immunity
- Rectal / vaginal prolapse
- Sudden death
- Pale / weak pigs
- Bloody faeces
- Reduced sow productivity
- Increased foetal re-absorption = return to oestrus
- Inconsistency of sow body condition
- Delayed puberty in gilts and boars
- Reduced libido
- Poorer semen quality = reduced fertility
- Higher incidence of liver and/or kidney disease
Table 2. Common mycotoxins and their effects on pigs
|Aspergillus flavus||Aflatoxin B1, B2, G1, G2||Liver necrosis, fatty infiltration of the liver, immune-suppression|
|Aspergillus ochraceus catum||Ochratoxin A||Renal nephropathy, immune-suppression|
|Pulmonary oedema, Immune-suppression
Vomiting, lethargy, loss of muscle condition
|Fusarium graminearum||Deoxynivalenol (DON, Vomitoxin etc.)||Vomiting, intestinal lesions, immune-suppression|
|Fusarium roseum||Fusarium verticillioides
|Hyperestrogenism, abortion, infertility, prolapses, ulceration|
|Claviceps purpurea||Ergotoxin||Reduced appetite, gangrene, agalactica, mammary gland failure|
Liquid or wet feeding systems can present a significant challenge to the pig industry with respect to mycotoxins. It is important to employ strict hygiene procedures to minimise the presence of mycotoxins within the mixer tanks, feed lines and troughs. Although regular cleaning should be performed, it should be noted that mycotoxins are extremely resilient and can survive in the biofilms of feed lines and equipment for significant periods. It is also important not to recycle the waste water after the system is cleaned as this serves to re-introduce mycotoxins into the system.