Nutritionist > Pig

Ochratoxin
Ochratoxin A is the most important of the ochratoxins which are produced by several species of Aspergillus (ochraceus) and Penicillum (verrucosum). Citrinine and oxalic acid are also produced by those moulds. Ochratoxins are ubiquitous in both tropical and temperate climates and are commonly found on oats, barley, wheat and maize. These moulds are capable of producing ochratoxin A (or more simply, "ochratoxin") at levels up to 10 parts-per-million (ppm). Such levels are rarely encountered, but ochratoxin is hazardous to pigs at much lower levels, typically 0.2 ppm (Krogh, 1991).

Ochratoxin introduced into the feed of monogastric livestock contaminates organs, fat, muscle tissue, and blood. If ingested over a long enough period of time by pigs, this mycotoxin can contaminate most of the edible tissues, and can produce enough kidney damage to result in carcass condemnation. Acute ochratoxicosis (concentrations greater than 5 ppm in the diet) is characterised by nephropathy (impaired kidney function), enteritis fatty liver, necrosis of the lymph nodes, immunosuppression along with a variety of other pathological conditions. In acute cases, death may occur due to acute renal failure. Interest in this mycotoxin has focused on the carcinogenic nature of the compound as it can accumulate in the meat of animals, leading to human health issues. Indeed, the Danish swine industry uses ochratoxin levels in kidneys as an indicator to measure the potentially harmful residue in pork products. Clinical signs and post-mortem findings are indicative of ochratoxicosis which can be confirmed by identifying the toxin in the feed or in the kidney at slaughter.

Pigs are quite susceptible to contamination owing to a rather long serum half-life of 72-120 hr. Recent surveys have detected ochratoxins as a natural contaminant of pig blood in Canada, and in many European countries, including Germany, Norway, Poland, Sweden, and former Yugoslavia. In addition, ochratoxin has been found in swine kidneys in the USA, Austria, Belgium, Denmark, Finland, Germany, Poland, Switzerland, Britain, and former Yugoslavia.

Ochratoxin residues in animal products are transmissible to consumers, and some national governments have taken stringent measures to allay consumer fears regarding their pork products. In Europe, for example, in 1997 maximum tolerances of 5 parts-per-billion (ppb) for ochratoxin were set for all foods, and Germany is presently enforcing its own 3 ppb limit. In Denmark, an entire swine carcass is considered contaminated, and is condemned, if 25 µg/mL ochratoxin is detected in the blood.

Clinical effects:
The main symptoms of ochratoxin poisoning include reduced growth rate and feed efficiency. Liver damage may occur, but the main effect is on the kidneys, resulting in interstitial fibrosis. Increased water intake (polydypsia), and hence increased urine output (polyuria) is a feature of this syndrome. In young growing pigs perirenal oedema may occur, with general stiffness. Gastric ulceration is also a consistent finding. Semen quality in boars is reduced affecting fertilisation rate and hence overall reproductive performance.

Clinical signs of ochratoxin poisoning include:

• Reduced performance (feed intake, growth rate, feed conversion efficiency)
• Pale and enlarged kidneys = tubular degeneration, interstitial fibrosis
• Impaired renal function = hyperproteinaemia, azotemia
• Kidney failure = mortality
• Increased water intake (polydypsia) and urinary output (polyuria)
• Suppression of cellular immunity = greater susceptibility to infection
• Reduced boar semen quality = reduced fertilisation rate = reproductive performance
• Oedema in piglets = stiff arched back, impaired gait
• Gastric ulcerations