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MOLECULAR AND ULTRA STRUCTURAL PATHOLOGY OF THIRAM (TMTD) INDUCED TIBIAL DYSCHONDROPLASIA (TD) IN EXPERIMENTAL BROILERS

Mekala Lakshman*1, Y.Anjaneyulu2, Ch.Srilatha3, D.Sreenivasulu4 and T.S.Chandrasekhar Rao5

*1Associate Professor & Officer- in-charge, Ruska Labs, Department of Veterinary Pathology, College of Veterinary Science, Rajendranagar, Hyderabad – 500030, and 2 &3Professors of Pathology, 4Professor of Veterinary Microbiology & Associate Dean, College(s) of Veterinary Science, Korutla and Tirupati, and 5Professor and Dean Faculty of Veterinary Science,
Sri Venkateswara Veterinary University (SVVU) – TI RU PATI.
E mail: 1 * (mekala_bry@yahoo.com)

Abstract
Introduction:
Tibial dyschondroplasia (TD) is a major metabolic cartilage disease of young poultry, which affects tibial growth plate cartilage (TGPC) cells fail to undergo osteogenic transition, resulting a thick white opaque avascular cartilage plug at the end of the proximal tibia and tibio-torsal bones. Thiram is a systemic fungicide used as a seed protectant and proven model compound to induce TD in young broilers. The experimental birds (420) were divided into twelve (12) groups. Group I is fed with basal diet (BD), group II & III fed with 60 & 100 ppm of Thiram (Terta Methyl Thiram Disulfide-TMTD) to induce TD, group IV, V and VI were fed with 200 ppm of copper sulphate (CuSo4), LivOdrian-FS (Herbal product-HP) and USCura Tox-FS (chemical product-CP) each 1g/kg as ameliorative agents. Group VII and VIII was fed with 60& 100 ppm of TMTD and 200 ppm CuSo4 , group IX, X was fed with as 60 & 100 ppm of TMTD and HP and group XI and XII was given 60 & 100ppm of TMTD and CP as a ameliorating agents respectively.
Results and Discussion:
Representative samples (TGP, liver and kidney) were collected during 5th, 10th and 15th day and on 1st, 3rd and 5th week from different groups for QRT-PCR (VEGF, VEGFR1, Bcl-2, MMP2 and MMP3), Immunohistochemistry (VEGF and Bcl-2), histopathology and Electron Microscopy and molecular and ultrastructural pathology was studied .
Regulation of TD specific genes like VEGF, VEGFR1 and Bcl-2 c t values were significantly lower in group III, VIII and X, MMP2 values were lower in groupV, VII and X and MMP3 lower values were observed in group IV, VIII and during 5th, 10th and 15th day of experiment. Up and down regulation of respective genes are playing a vital role in causation of and repair of TD lesion.
The TEM of TGPC revealed apoptotic cartilage cells in the early age and large lipid inclusions, vesuculated and deranged stacks of rough ER along with apoptotic cells which had a cytoplasmic cresentric cap like structures of condensed chromatin is indicative of early cell death. The liver of different groups have shown moderate to severe changes like cytoplasmic vacculation, margination of chromatin, disrupted nucleus, and swollen mitochondria with loss of matrix. The kidney samples revealed swelling of nucleus, margination of chromatin, condensed and vacuolated mitochondria, and narrow tubular lumen was observed among TMTD fed group..
The SEM lesions of TGPC revealed necrotic areas of cartilaginous structures, and complete loss of haversion system, where as in liver moderate to severe dilation of CV with perivascular space and necrotic parenchyma and kidney samples revealed moderate swelling of tubules with completely closed lumen and moderate to severe hemorrhages. The comparative sub cellular changes are significant in TMTD treated birds than absolute control; among ameliorative agents CuiSO4 is superior over HP and a CP. The results assume great significance and there is dire need for further investigation in this area to minimize the economic losses due to TD in broilers.

Comments

arup_igcar's picture

Good work

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