“CADMIUM (Cd) AND THIRAM (TMTD) INDUCED TOXICOPATHOLOGY IN EXPERIMENTAL BROILER CHICKEN”
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Date
2019-04-26
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pvnrtvu
Abstract
Thiram (TMTD) is a systemic fungicide commonly used for treating corn and other grains intended for seed purposes and also for storage of food grains. TMTD treated grains occasionally find their way into the market.
Cadmium (Cd) is a naturally occurring element present in soil and water. Additionally, it is released into atmosphere from wide range of anthropogenic sources as a mobile element that is taken up by the plants and animals and bioaccumalated in the organs. The Cd is broadly distributed in the environment and present in minor levels in sea water and in a wide range of animal and plant species. Human activities such as production of dyes, plastics, dry batteries and porcelain etc., have increased Cd contamination in the environment.
Adequate literature was published about TMTD and CdCl2 (Cadmium chloride) induced toxicity in experimental animals including poultry. In pursuance of literature the mixed toxicity (CdCl2 + TMTD) studies in poultry are obscure. The occurrence of mixed toxicity could be possible due to increased environmental pollutants (Industrial and Agricultural) in developing countries more particularly in India.
Hence, the present experiment was designed to study the pathology of TMTD, CdCl2 and TMTD+ CdCl2 induced toxicity in broiler birds. A total of 100 day old broiler chicks were procured and individually weighed and distributed into four (4) groups of 25 each, reared under identical managemental conditions for a period of 42 days. All the chicks were allowed to acclimatize for 7 days. From 8th day on wards, group 1 birds were fed with basal diet (control), group 2 fed with 60 ppm of TMTD, group 3 fed with 100 ppm of CdCl2 and group 4 fed with TMTD + CdCl2 at same dose rate, for a period of 35 days. Clinical signs and weekly body weights were recorded for statistical analysis. Significantly (P≤0.01) lower weights were recorded in birds of group 2, 3 and 4 than group 1.
Six birds from each group were sacrificed on 14th, 28th and 42nd day of the experiment and the blood and serum samples were collected prior to sacrifice for estimation of haemato-biochemical parameters. The slices of liver, kidneys, spleen, heart and proximal extremity of tibial bones were collected for estimation of tissue biochemical profiles, histopathological and ultrastructural studies.
A significant decrease in weights of liver, spleen, lungs, heart and tibial bones were recorded on 14th, 28th and 42nd of experiment. Haemotological parameters viz ; total erythrocyte counts (TEC), haemoglobin (Hb) concentration, packed cell volume / haematocrit (PCV/ Hct) and erythrocyte indices (Mean corpuscular volume - MCV; mean corpuscular haemoglobin - MCH and mean corpuscular haemoglobin concentration - MCHC) values were significantly decreased, whereas total leucocyte counts (TLC) were significantly increased in groups 2, 3 and 4 during the experiment. Significantly, increased levels in serum globulin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), creatinine and uric acid were observed while decreased levels of albumin and total protein (TP) were recorded on 14th, 28th and 42nd day of experiment in groups 2, 3 and 4. A significantly (P< 0.05) increased levels of thiobarbuturic acid reacting substances / malondialdehyde (TBARS / MDA) and significantly decreased levels of reduced glutathione (GSH) concentration in groups 2, 3, and 4 were recorded on 14th, 28th and 42nd day of experiment.
Histopathologically, most of the toxic groups liver sections showed dilatation of central vein (CV), perivascular necrosis with mild infiltration of mononuclear cells (MNC’s) in the vicinity of central vein, shrunken portal triad with degenerative changes, mild periportal necrosis and periportal fibrosis. A few other sections showed periportal cirrhosis and some other sections revealed perivascular cirrhosis along with infiltration of round cells admixed with fibrous tissue.
Kidney sections showed distorted tubular architecture, degeneration and necrosis followed by desquamation of epithelial cells and presence of hyaline casts. Severe congestion of renal artery, intertubular haemorrhages were observed in kidney sections on 28th day of experiment. Additional lesions like intertubular infiltration of MNC’s, degeneration of tubular epithelial cells with pyknotic nuclei, swollen to shrunken glomeruli with hypercellularity, increased Bowman’s space, atrophied glomeruli, dilated collecting tubules and hyaline casts were also observed in most of the sections on 42nd day of experiment.
In spleen, the histopathological lesions observed were mild hypoplasia of white pulp and red pulp on 14th day of experiment. Sections of spleen on 28th day revealed an indistinct red pulp and white pulp, thickened splenic arteries and dilated sinusoids. On 42nd day of experiment, spleen sections showed tight adherence of splenic capsule to the cortex, basophilic hypercellularity beneath the capsule, severe endothelial disruption, mild infiltration of MNC’s in the vicinity of blood vessels and vacuolar degeneration of endothelium.
Heart sections of toxic group birds revealed loss of striations, thickened wall of vessels, mild perivascular cuffing, mild to moderate perivascular proliferation of fibrous tissue, mild congestion, and dilatation of myofibrils were noticed on 14th and 28th day of experiment. Interfibrillar haemorrhages, perivascular and vacuolar degeneration, pyknotic nuclei of myofibrils were observed on 42nd day of experiment.
The histopathological sections of proximal extremity of the tibial bones showed a marked increase in thickness of hypertrophic and thin proliferating zones with condensed matrix and avascularization were observed in TMTD group birds. The CdCl2 treated birds showed thick proliferating zone and thin hypertrophic zone that were connected with numerous capillaries.
Histopathological lesions in liver, kidneys, spleen, heart and tibial bone were mild, moderate to severe and progressive on 14th, 28th and 42nd day of experiment in respective toxic groups, but the changes were more pronounced in group 4 than groups 2 and 3.
Liver sections under scanning electron microscope (SEM) revealed distortion and dilation of hepatic cords, degeneration of hepatocytes with increased micro porosity and granular surface. Mild congestion, haemorrhages around portal vein and sinusoids along with proliferation of fibrous tissue were evidenced in toxic groups. Kidney slices of toxic groups under SEM revealed dilation, haemorrhages and proliferation of fibrous in intertubular space, swollen to shrunken glomeruli with mild increased Bowman’s space. The tibial bone slices of group 4 revealed undifferentiated/indistinct zones with varying degree of thickness, and distinct zones were observed in TMTD and CdCl2 groups.
Section of liver under transmission electron microscope (TEM) revealed dilated sinusoids, distorted rough endoplasmic reticulum (RER), electron dense granular material in the cytosol, increased number of distorted mitochondria (swollen to condensed) and mild margination of electron dense chromatin, pyknotic and swollen nucleus in toxic groups. Sections of kidneys under TEM showed loss of architectural details, dilation of tubules and intertubular capillaries, loss of brush border in proximal convoluted tubules (PCT) and loose intertubular junctions in toxic groups. Sections of tibial bones under TEM revealed swollen to pyknotic nuclei with severe margination of chromatin, mild dilation of nuclear membrane, electron translucent matrix, and irregular vesicular cytoplasm containing dilated RER. A few sections showed swollen chondrocytes with condensed mitochondria, disrupted RER.Often, other sections revealed swollen nucleus with margination of chromatin, irregular and coalesced RER and condensed electron dense mitochondria in toxic groups.
In conclusion, the present study suggested that TMTD, CdCl2 and its combination is responsible for significant changes in haemato-biochemical parameters, oxidative stress enzymes alterations in liver and kidneys which could be due to abnormal generation of free radicals which led to impairment of antioxidant defenses. Finally, these changes resulted in macroscopic and microscopic pathological changes in liver, kidneys, spleen, heart and tibial bones.
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D-631
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