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Theses

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1998 - 19995
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Subject: Veterinary Pathology × Author: KAU × End date: 1999 × Start date: 1998 ×
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    ThesisItemOpen Access
    Determination Of Permissible Level Of Aflatoxin In Broiler Chicken Feed
    (Department of Pathology, College of Veterinary and Animal Sciences,Mannuthy, 1999) Arulmozhi A; KAU; Koshy Varghese
    The study was undertaken to assess the effect of various levels of aflatoxin on the performance of broilers and to establish the permissible level of aflatoxin in the broiler feed. One hundred and eighty day old broiler chicks were divided into six groups of 30 birds each and were given feed containing graded levels of aflatoxin at 0, 20, 40, 60, 80 and 100 ppb for a period of 45 days. Feed intake, weekly body weight gain, feed efficiency, haemogram, serum profile, organ weight, residual aflatoxin in tissues and pathological changes in liver, kidney, bursa and spleen were studied at fortnightly intervals to evaluate its dose related effects. A dose dependent decrease in the daily feed intake and mean body weights were noticed in all the groups. The cumulative FeR was extremely poor at 80 and 100 ppb levels at sixth week of age. The toxicopathological changes in the birds varied in its intensity in relation with the level of aflatoxin in the feed, with most severe changes being at higher dose levels. The values of haemoglobin, PCV, total leucocyte count, Iymphocytes, total serum protein and albumin showed a decrease whereas the ESR, heterophil and serum enzyme were increased. The aflatoxin, even at 20 ppb levels caused degenerative and necrotic changes in liver and kidneys and the intensity of the lesions increased with higher levels of toxin. Attempt for regeneration and repair processes were well pronounced by the 30th and 45th day. Lymphoid depletion was a characteristic feature in bursa and spleen. Degeneration and lysis of lymphocytes with cys; formation was also seen in bursal follicles. Residual aflatoxin was detected in the liver and muscle in all groups by the 45th day. The net returns from the toxin treated birds showed a dose related decline compared to control and the loss in profit at 20 ppb level was marginal About 24 per cent of the poultry feed samples tested during the period from January to July 1999 were contaminated with aflatoxin quantitatively ranging from 20 to 200 ppb. The results of the present study shows that even at 20 ppb aflatoxin causes cellular and subcellular damage to the tissues. However, the economic loss at this level was marginal when compared to higher dose levels. Hence 20 ppb can be considered as permissible level in broiler chicken feed.
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    ThesisItemOpen Access
    Immunopathological response of the duck (Anas platyrrhyncos domesticus) to sublethal dose of selected agro-chemicals
    (Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) Vijayan, N; KAU; Valsala, K V
    The study was conducted with the objective of assessing the teratologic, embryotoxic and immunopathologic effects of two agro-chemicals carbofuran and 2,4-D used in agricultural operations, on duck embryos and ducklings. The embryological studies included the observation on the embryonic defects and weight of the lymphoid organs along with the histopathologic and ultrastructural studies of the lymphoid organs like the bursa, spleen and thymus. The results showed that the contamination of the eggs with the above chemicals caused moderate deleterious effects on the lymphoid system, though no teratologic effects could be observed. The histological and ultrastructural changes also confirmed the deleterious effects at the tissue and cellular level. The immune system of the ducks exposed to the above chemicals for two different durations were assessed using a battery of tests. The humoral immune system was assessed based on the body weight, lymphoid organ weight, haematological evaluation, serum biochemical evaluation and the evaluation of HI titre against NDV. The cell-mediated immune system was assessed by the skin reactivity tests to DNCB and PHA. LMIT and GVHR were also employed to assess the cell-mediated immune system. The histological and ultrastructural studies were also conducted after six weeks and ten weeks of the experiment. The assessment of the immunological profile employing these elegant tests revealed that these agro-chemicals caused mild but significant suppression of the cell-mediated and humoral immune response. By this investigation it was clarified that these agro-chemicals have mild to moderate degree of immunotoxic effect when exposed for a short duration, but the changes were severe when exposed for longer duration. From the .studies, it was demonstrated that the immunotoxic effect of carbofuran is more compared to 2,4-D (herbicide) and the changes were dose and time dependent.
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    ThesisItemOpen Access
    Pathological effects of aflatoxicosis in ducks
    (Department of Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1999) Latha, K; KAU; Mammen, J Abraham
    In this investigation the pathological effects of aflatoxicosis and permissible levels of aflatoxin were studied at different dose levels viz. 5ppb, 10ppb, 20ppb and 40ppb. In the aflatoxin fed ducks, reduced feed intake and diarrhoea were noticed. There was a significant reduction in the body weight and carcass weight which were indicative of the toxic injury to the gastrointestinal tract. There was a significant increase in the liver weight reflecting the damage to the hepatic system. There was reduction in the haemoglobin concentration, total erythrocyte count, packed cell volume and significant increase in the erythrocyte sedimentation rate indicating the adverse effect of aflatoxin on the haemopoietic system. Leucocytosis with heterophilia and lymphopenia were observed suggesting the deleterious effect of aflatoxin on the lymphoid organs. Highly significant reduction in serum total protein, albumin values, AlG ratio and significant increase in globulin were observed indicating hepatic damage. Grossly, the aflatoxin fed birds showed pale enlarged liver, focal necrotic areas, subcapsular haemorrhage, fatty liver, greenish discolotation and surface granularity and nodularity of varying intensity depending on the dose and duration of the treatment. In the kidney and spleen, mild congestion were observed. Bursa showed atrophic changes. Histopathological alterations in the liver consisted of biliary hyperplasia, fatty changes, congestion of the hepatic sinusoids portal venous congestion, portal fibrosis, focal collection of mononuclear cells, dissociation of hepatocytes, hepatocytomegaly and fibrous tissue proliferation of varying intensity depending on the dose and duration of the treatment. In the spleen, congestion, vascular sclerosis and depletion of Iymphocytes in the cortical and paracortical areas were noticed, whereas in the kidney besides nephrosis, mild peritubular accumulation of mononuclear cell were noticed at 20ppb level of aflatoxin while tubular degeneration, swelling of the tubular epithelium, mild fibroblastic proliferation with cellular infiltration in the interstitium were noticed at 40ppb level. Generally, bursa of fabricius of the treated birds revealed lymphoid depletion in the follicles, interfollicular edema and proliferation of interfollicular connective tissue. Aflatoxin treated groups showed dose and duration dependant degrees of ultra structural changes. The ultrastructural changes noticed were intact cell nucleus with prominent nuclear pores, increased amounts of heterochromatin that appeared as clumps, dilatation and degranulation of rough endoplasmic reticulum (RER), rounded, oval or elongated mitochondria which were either normal or swollen containing swollen cristae along with the presence of electron dense material within the matrix, smooth endoplasmic reticulum (SER) that appeared as small tortuous vesiculated structures and scattered lipid droplets. Aflatoxin B1(AFB1) residues were detected in the liver, muscle pooled samples of th.e kidney and blood of birds maintained with feeds containing • aflatoxin at levels of 20 and 40 ppb during the fourth, sixth and eighth month. No residual toxin could be detected in birds treated with aflatoxin at a level of 5ppbthroughout the experiment. At dose level of 10ppb, no AFB1 residues could be detected by the second and fourth month, but during the sixth and eighth month negligible amount of residues could be detected in the liver and muscle. This study highlights the pathological effects of aflatoxicosis in ducks. Moreover, the adverse effects on the hepatic, haemopoietic and renal systems could be documented. By considering the above facts aflatoxin level of 10ppb is fixed as permissible level in ducks. However, permissible level can vary with the season, diseased conditions of the bird and storage practices of feed. Therefore, this study emphasizes the need for regular screening of feed for aflatoxin content.
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    ThesisItemOpen Access
    Pathology of bacterial mastitis in bovines
    (Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) Nandakumar, S; KAU; Sreekumaran, T
    The pathology of bacterial mastitis in bovines was studied considering the following aspects such as bacterial isolation; changes in milk, antibiotic sensitivity pattern, haematology, whey protein pattern and histopathological examination of the mammary gland and supramammary Iymphnodes. Two hundred and sixty two samples were found to be subclinically positive based on California Mastitis Test. The organisms isolated from clinical and subclinical cases were Staphylococcus, E. Coli, Gram negative bacilli, mixed infections, Streptococcus, Yeast and Gram positive bacilli in the decreasing order of prevalence. All the major pathogens were sensitive to pefloxacin, gentamycin and chloramphenicol and resistant to penicillin. Leucopenia could be noticed in clinical and subclinical cases of mastitis. Relative neutrophilia could be observed in mastitic animals. Total plasma protein was also increased. There was an increase in T-Iymphocyte count in mastitis affected animals. ~omatic cell count was increased in clinical and subclinical cases, but was not indicative of infection, unless confirmed by bacteriological examination. SOS-PAGE on whey proteins revealed an increase in protein content in mastitic milk as a result of the plasma proteins, cellular proteins, bacterial proteins. There was marked increase in immunoglobulins in mastitic milk, when compared to normal. Histopathology of mammary glands revealed the presence of inflammatory cells in the acini and interstitium of mammary glands as the main lesion. Varying degrees of inflammatory reaction could be noticed in almost all the quarters. Supra mammary lymph nodes revealed distension of subcapsular sinuses, active secondary follicles in the cortex, sinus catarrh and medullary hyperplasia in mastitis affected animals.
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    ThesisItemOpen Access
    Comparative pathology of aflatoxicosis in the duck and fish with special reference to the immune system
    (Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) George, K C; KAU; Rajan, A
    Pathological responses of ducklings and juvenile Indian carps Labeo rohita in experimental aflatoxicosis were studied. Both the ducklings and fishes were given sublethal toxic levels of aflatoxin B1. The ducklings and fishes were exposed to aflatoxin B1 for 2, 4, 6 and 8 weeks respectively and they were sacrificed at the end of the experiment and samples for haematological, serum protein profile, histological and ultrastructural investigations were collected. Pathological changes were studied with special reference to the humoral and cell – mediated immune responses. Among the haematological parameters, total erythrocyte count, total leucocyte count and packed cell volume were found to be reduced in fishes. The reduction was directly proportional to the duration of aflatoxin treatment. In the fishes, there was moderate fall in the total proteins and the albumin. The electrophoretic picture of the serum of the fishes also showed fall in the albumin fractions. In the ducks there was severe reduction in the albumin level and this was reflected in the electrophoretic picture as well as A: G ratio. In both the ducks and the fishes humoral immune response was suppressed due to aflatoxin treatment. Antibody titres against sheep RBC fell in the experimental groups of the ducks and the fishes. The cell - mediated immunity was assessed in the ducks and the fishes by intradermal PHA – M response, count of ANAE positive lymphocytes in the peripheral blood and leucocyte migration inhibition test. In the ducks and the fishes of the aflatoxin treated groups, there was significant fall in the skin sensitivity response and also in the number of ANAE positive lymphocyte. These findings clearly established that CMI was suppressed by aflatoxin . The histological and electron microscopic studies revealed severe degenerative and necrotic changes in the hepatocytes in the ducks and fishes. However, hepatosis was more severe in the fishes whereas in the ducks biliary proliferation was a prominent feature. The hepatic changes could be correlated with the changes in the plasma protein profile in the duck and the fish. The lymphoid organs of the duck and the fish (thymus, spleen, bursa of Fabricius and anterior kidney) showed extensive necrosis and degenerative changes. These changes clearly established the reason for the immunosuppression and low leucocytic counts observed in the aflatoxin fed ducks and fishes. The kidneys of the duck and the fish exhibited nephrotic changes. Degenerative changes were also observed in the brain and the heart of the two species. The pathologic changes due to aflatoxicosis were comparable in the ducks and fishes.