Palanivel, K.M.Sulficar, S.TANUVAS2016-07-262016-07-262012http://krishikosh.egranth.ac.in/handle/1/69944The present study has taken up the molecular and seroprevalence of bovine paratuberculosis in dairy animals, the impact of managemental risk factors on the occurrence of Mycobacterium avium subsp. paratuberculosis (MAP) and diagnosis of the disease. The work was carried out with varying environmental factors located in and around Namakkal districts of Tamil Nadu between 2009 - 2012. The investigation was done on 500 animals comprising 378 white cattle and 122 buffaloes. Management practices like low sanitation of periparturient cows udder contaminated with manure, dirty calving area, history of Johne’s Disease (JD) in the herd, had an influence on the prevalence of disease. A total of 500 sera, milk and faecal samples were collected and subjected to MAP antibody and antigen detection. The seroprevalence of MAP antibody was detected 57 (15.07 per cent) and 15 (12.29 per cent) in cows and buffaloes with an overall seroprevalence of 14.4 per cent of JD in dairy animals based on the diagnostic test ELISA. Breedwise seroprevalence 32 (14.74per cent), 20 (18.69 per cent), 3 (12 per cent), 2 (6.89 per cent) in Jersey cross breed, Holstein Friesian cross breed, Red Dane cross breed, Non-descript white cattle and 7 (8.86 per cent), 8 (18.60 per cent) in Nondescript and Murrah graded buffaloes respectively. There was no statistical significant difference (P>0.05) within species and breeds. Higher seroprevalence was observed in bovines between 4.5 - 6.5 years of age and above 6.5 years of age when compared to less than 4.5 years of age. The seroprevalence of MAP was higher in pleuriparous animals (16.98 per cent) when compared to primiparous animals (7.4 per cent). There was significant difference at (P>0.05) between pleuriparous and primiparous animals. The stage of lactation does not have impact on MAP seroprevalence (11.31 per cent, 17.79 per cent and 15.51 per cent) in early, middle and late lactation of dairy animals respectively. Out of 500 faecal and milk samples screened by PCR and Ziehl-Neelsen staining technique in which 82 (16.40 per cent), 59 (11.80 per cent) and 20 (4 per cent) animals were found to be positive for MAP. The per cent positivity by faecal, milk PCR and Ziehl-Neelsen staining technique in cows were 16.93 and 14.75, 12.43 and in buffaloes 9.83, 4.23 and 3.27 respectively. The chi-square analysis revealed a highly significant difference (P<0.01). The value of kappa statistic of faecal PCR in agreement with that of mlk PCR, ELISA and Z-N staining were 0.6136, 0.5705 and 0.3504 in bovines. The PCR amplified products of IS900 gene of MAP were sequenced by dideoxy chain termination method and by blast analysis the field isolates were found to be having hundred per cent homology to strain K-10 of MAP. Soil pH was not identified as a significant risk factor, but contamination of udders of periparturient cows with manure (OR = 21.2, P = 0.00), lack of cleanliness in the calving area (OR = 3.8, P = 0.06) and history of having suspected cases of Johne's disease in the animals (OR = 24, P = 0.03) were significantly associated with the infection status of dairy animals in Namakkal.enThesis