Poultry products such as meat and eggs are considered as preferred and most efficient ways of obtaining nutrition for human beings. Poultry meat, in particular, is supposed to be a high quality food owing to its excellent biological and nutritional value.
It is an enriched source of protein with a high amino acid profile and low energy content. A healthy diet therefore is one which is well-balanced, nutritious and palatable to people. Poultry birds are susceptible to a number of toxins such as mycotoxins that may get entry in birds via ingestion, inhalation, and direct contact with mycotoxin contaminated feed.
Ochratoxin is a mycotoxin which is produced by some species of Aspergillus and Penicillium which may lead to residues in edible tissues of slaughtered broiler birds. Their presence in feed poses serious hazards to the consumers’ health and productivity.
There are three types of ochratoxins naming Ochratoxin A, ochratoxin B and ochratoxin C. Among these three types ochratoxin A is most prevalent. OTA in poultry food chain comes as a source of contamination from cereals (corn, wheat, barley, oats, rye, and sorghum) and soya. These molds invade the crop in post-harvest phase.
Most important factors influencing the mycotoxin growth is water availability and temperature. Optimum temperature for Ochratoxin formation is 15-30°C with a relative humidity of 85% and moisture content in grains higher than 14%. The highest levels of OTA recommended by the EU legislation is <50 µg/kg.
Toxins on contact with body tissue surface of affected birds undergo epithelial sloughing of mucous membranes of skin, respiratory tract, gastrointestinal, reproductive, and urogenital system leading to toxaemia, where it may persist for long time and accumulate in organs responsible for its detoxification and excretion.
The severity of toxaemia depends upon target site, dose of toxins, duration and frequency of contact with the toxin, mechanism of toxicity, immune status of bird and environmental factors. Pathogenesis of ochratoxicosis at molecular level has revealed that Ochratoxin inhibits DNA, RNA, and protein synthesis by inhibiting the enzyme phenylalanine-tRNA synthetase at cellular level.
Carbohydrate metabolism in kidneys is affected due to reduction in the renal mRNA coding for gluconeogenesis enzyme i.e. phosphoenolpyruvate carboxykinase. The target organ for ochratoxicosis is kidney and it is known to be nephrotoxic. Ochratoxin residues are found in liver, kidneys, muscles and eggs which ultimately prove to be carcinogenic when consumed by human beings
Pathological effects in poultry:
Clinical signs of poultry birds suffering from ochratoxicosis are reduced weight gain, poor feed conversion, anaemia, reduced egg production, poor quality shelled egg, blood/meat spots in yolk or albumin, watery thin albumin, poor feathering, abnormal pigmentation of shanks, increased water consumption, immuno suppression, delayed onset of sexual maturity, and nephrotoxicity.
In parent stock reduces hatchability and poor progeny performance is seen. Ochratoxicosis induced pathological lesions in different organs include swollen and pale kidneys with severely distended uerters owing to urates deposition, yellowish and friable liver, atrophy of bursa and thymus, spleenic degeneration, and soft and fragile bones.
Histopathology of infected Ochratoxin residual organs showed vacuolation and megalocytosis of hepatocytes, hypertrophy of renal proximal tubular epithelial cells.
Pathological effects in human:
Human exposure to OTA intake is due to consumption of contaminated poultry by products with Ochratoxin. Maximum recommended level of ochratoxins in human diet by World Health Organization (WHO) is 3-5 µg/kg. OTA was classified as a possible carcinogen (Group 2B) to humans by The International Agency for Research on Cancer (IARC) so is a potential genotoxin causing tumor development.
OTA is associated with Balkan Endemic Nephropathy and human renal disease and have potential nephrotoxic, teratogenic, immunotoxic and neurotoxic properties in human beings consuming infected poultry meat..
Infected pregnant women transfer toxins to progeny during pregnancy or after birth via breast feeding. OTA is detected in human fluids such as blood, milk and feed ingredients through isolation, identification and quantification by HPLC and ELISA.
In conclusion, feed contamination by OTA and its deleterious effects on poultry birds and human health suggests an imperative need of risk assessment and microbial detoxification. So that, poultry birds and human can be protected from the deleterious effects of ochratoxins.
Authors: Shunazia Saquib*1, M. Tariq Javed1, Aisha Khatoon 1, Ashiq Ali1,Sania Saeed1,Farwa Rabab 1.
1 Department of Pathology, Faculty of Veterinary Science, University of Agriculture Faisalabad, Pakistan.
* Corresponding Author Email: firstname.lastname@example.org