Effect of Aflatoxin on Feed Conversion Ratio in Broilers: A Meta-Analysis (Report‪)‬

INTRODUCTION Mycotoxins are toxic secondary metabolites of certain fungi and cause illness or death when ingested by animals or human beings (Qazi and Fayyaz, 2006). One of the most toxic group of mycotoxins are the aflatoxins (AFs), produced by the fungi, Aspergillus flavus and Aspergillus parasiticus. Aflatoxins were first discovered in 1960 in England after the outbreak of "Turkey-X-disease" during which 1 million turkey poults died in England due to the toxin (Blount, 1961). They are natural contaminants of poultry feeds and feed ingredients, maize, sorghum, pearl millet, rice, peanut meal and cottonseed meal (Reddy et al., 2000). Contamination of feeds and feed ingredients may occur at any time before and after harvest and drying, during storage, processing and manufacturing. Chemically, aflatoxins are a group of difuranocoumarin derivatives and the major types of aflatoxins are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). Among the aflatoxins, AFB1 was identified to be the most toxic and most prevalent compound, followed by G1, B2 and G2 with decreasing toxicity (Murphy et al., 2006). Aflatoxin intake in broilers is associated with liver damage, poor performance, immunosuppression and mortality. Aflatoxin toxicity in poultry is also associated with biochemical, hematological, reproductive and pathological changes (Ortatatli and Oguz, 2001). Some of the metabolites formed during the metabolism of AFB1 are transmitted to edible animal products, liver, muscle ((Bintvihok and Davitiyananda, 2002) and eggs, which exert immunosuppressive, embryotoxic and teratogenic effects (Celik et al., 2000; Oliveira et al., 2000). Besides affecting the health of birds and consumers, aflatoxins also cause economic losses to poultry industry. The Council for Agricultural Sciences and Technology recorded an annual crop losses of $932 million due to mycotoxin contamination and additional losses of $466 million in efforts to prevent or reduce contamination (Richard and Payne, 2003).