Asian Research Thesis Index

Abstract

Ochratoxin A (OTA) exerts nephrotoxic, hepatotoxic and carcinogenic effects in animals and humans. OTA is also responsible to induce oxidative stress and immunosuppression. The presence of OTA as a common contaminant of cereal based food and feed ingredients has been reported from different regions of the World including Pakistan. Keeping in view the toxic significance of OTA, the present study was planned to study the pathological effects of OTA in chicken, with a focus to develop a relationship of pathological alterations associated with age, exposure duration, dietary and tissue/organ ochratoxin levels. Experiments were conducted to induce acute ochratoxicosis in one day old (experiment 1) and 21 day old (experiment 2) broiler chicks by feeding rations containing 0, 1.6, 3.2, and 6.4 mg/kg OTA for 10 days. Chronic ochratoxicosis was induced in day old broiler chicks by feeding 0, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/kg OTA for duration of 21 (experiment 3) and 35 days (experiment 4). Different parameters studied included feed intake, body weight, organ weights, clinical signs, gross and microscopic morphological alterations in different organs/tissues, immunological responses, oxidative stress parameters and OTA tissue residues. Present study concluded that the ochratoxicosis in broiler chicks resulted in the poor feed intake, weight gain and performance of birds, increased mortality and severity of clinical signs in dose dependent manners. OTA feeding in broilers resulted in the suppression of immunological responses and decreased blood and tissue antioxidant potentials. OTA related decrease in antioxidant potential and immunosuppression was directly proportional to the dose and duration of OTA exposure. OTA exposure in older birds resulted in more severe oxidative stress but lesser immunosuppression as compared to birds exposed at young age. Dose related increase and age related development of resistance to the pathological and biochemical alterations were also recorded. Decreased carnosine, anserine and creatine contents of muscles following OTA exposure suggested the production of low nutritional and keeping quality chicken meat. Exposure of OTA both acute and chronic dietary levels resulted in the accumulation of OTA residues in liver, kidney and muscles of the birds although these residues quickly disappear after withdrawal of toxin contaminated diets.

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