The objective of present study was to establish a relationship between aflatoxin induced pathological alterations, dietary and tissue AFB1 levels. Aflatoxin used in the experiments was produced by inoculation of rice with Aspergillus flavus (CECT 2687 Spain) and its AFB1 concentration was determined. In experiments 1-3 broiler chicks of 7, 14 and 28 days of age were offered feeds containing 0, 1600, 3200 and 6400 ug/kg AFB1 for 7 days. In experiment 4 broiler chicks of 14 days of age were kept on feeds containing 0, 50, 100, 200,400 and 800 ug/kg AFB1 for 28 days.
Clinical signs in intoxicated birds included depression, ruffled feathers, decreased interest in feed, increased water intake and soft to watery feces. Birds fed 800 ug/kg AFB1 for 28 days also exhibited nervous signs. Mortality occurred in all treatment groups with the exception of those given 50 and 100 ug/kg AFB1 for 28 days in experiment 4.Score of clinical signs and mortality percentages in these experiments increased with the dietary AFB1 levels and decreased with increase in age of birds. A significant decrease in body weight was observed in all groups with the exception of birds given 50 and 100 ug/kg AFB1 for 28 days. Decrease in body weight occurred in a dose related manner and was less severe in older birds than young ones.
Pathological lesions in birds of treatment groups included pallor discoloration of liver and enlargement of liver and kidneys. Hemorrhages were present on different organs of the body. Microscopically congestion of liver parenchyma, cytoplasmic vacuolation/fatty change of hepatocytes, necrosis of hepatocytes, newly formed bile ducts, mononuclear and hetrophilic cell infiltration were observed in aflatoxin fed broiler chicks. Kidneys of AF intoxicated birds were enlarged and microscopically revealed degeneration and necrosis of tubular epithelial cells, congestion and hemorrhages of the parenchyma. A significant increase in scores of gross and microscopic lesions occurred with increase in the dietary levels of AFB1 in all experiments. A comparison of scores of gross and histopathological lesions in birds of different age groups kept on same dietary AF level in experiments 1-3 revealed a significant decrease in scores with increase in age.
Serum alanine transferase and alkaline phosphatase levels significantly increased in aflatoxin administered birds in dietary AFBl dose related manner. A significantly lesser degree of increase in these enzymes occurred with increase in age of the birds suggesting an age related development of resistance to aflatoxins. A significant decrease in serum albumin, total proteins and globulin concentration was observed in the present study in all aflatoxin intoxicated birds.
AFB1 residues were detected in liver and muscles of birds of all the groups in four experiments following 2-5 days of consuming AF contaminated feeds, however, AFB1 could not be detected in tissues of birds fed 50 ug/kg and muscles of those fed 100 ug/kg AFBI for 28 days. Highest levels of AFB1 were 6.97 and 3.27 ng/g in liver and muscles, respectively. AFB1 residues in tissues of birds of different age groups on the same dietary AF levels decreased with increase in age. AF in livers and muscles in the present appeared earlier in birds fed high dietary AF levels and late in group fed low dietary AF levels.
Elimination of AFB1 from the tissue in the present study was rapid in older birds compared with young ones. As AFB1 was detected in liver of birds from all treatment groups with the exception of those fed 50 ug/kg AFB1, it can be a potential candidate as a diagnostic tool for confirmation of aflatoxicosis in birds suspected on the basis of clinic- pathological observations.