DETECTION OF MYCOPLASMA GALLISEPTICUM ANTIBODIES IN THE SERA OF LAYER FLOCK, NEPAL
A study was conducted in layer flocks of poultry at Chitwan district to determine the serum antibody titre. The proFLOK MG ELISA kit, a rapid and specific presumptive screening test for the detection of antibody to most conventional Mycoplasma gallisepticum strains in chicken serum samples was used in this study. A total of 89 samples from different age groups from 19 flocks were examined. The findings of this study showed that the prevalence of the Mycoplasma gallisepticum was 34.8 %. The probable and negative samples were 57.3% and 9% respectively. The prevalence is significant (p<0.05) statistically. On the basis of flock 15.8% showed positive,10.5% have negative and 73.7% have probable antibody status. The flock with high MG titre has also high mortality pattern. Breeder farm has low level of MG titre (355.05±179.45) as compared with commercial flock (854.48±179.45). Among different age group 5 to 9 months age groups were most susceptible to MG infection.
Mycoplasma gallisepticum (MG) is a cause of chronic respiratory disease(CRD) which drop in egg-production, reduced feed conversion, severe airsacculitis, coughing and respiratory rales with heavy condemnations of carcass at processing. MG is egg transmitted and may be spread laterally by direct or indirect contact. Mycoplasma infections of poultry may be readily confused with other respiratory diseases and may be obvious only when present in conjunction with complicating respiratory infections such as Newcastle disease or infectious bronchitis (Fpibcro, 2001).Mortality caused by CRD is about 15.46% of total mortality (Sharma, 1986).MG infection has been one of the costliest disease problems confronting the poultry production (Yoder, 1984).With the rapid growth of poultry production in Nepal, there has been concentration of large number of birds into small areas leading to increased risk of MG infection.
MG infection is also known as PPLO infection, CRD and infectious sinusitis. MG causes a highly contagious disease that affects chickens (breeders, layers, broilers) and turkeys. It is a global problem. Chicken and turkey are natural hosts. Very young birds are more susceptible. They causes haemagglutination of the erythrocyte which ferment glucose with acid production (Calnek et al., 1994)
This study was undertaken to determine prevalence rate of CRD in Chitwan and to compare influence of age and manage mental variation on MG titer.
Material and Methods
A total of 89 samples from 19 flocks were collected at Chitwan randomly for routine serologic flock monitoring for MG. Flock history, size, vaccination schedule, CRD prevention programming, mortality pattern etc were recorded. Samples were stored at 4oC and centrifuged to separate serum. Sample dilution procedure, preparation of the serum dilution plate, preparing the test plate, manual processing of data, interpretation of results was done as accordance with ELISA test procedure of proFLOK MG ELISA kit.
Results and Discussion
Out of 89 Chicken sera tested, 31(34.83%) samples gave positive reaction and the titer value varied from 777.40 to 3459.4. Almost similar findings 36.7 % and 36.5 % have been reported by Biswas et al., 1993 and Boussetta et al., 1997 respectively. Higher prevalence ( 58.09% ) has been reported by Dhakal, 2000 by field surveillance study in Chitwan district. Commercial ELISA on serum samples from 460 birds in 52 flocks showed that 33 % of the birds had been exposed to MG and MS (Kelly, 1994). Samples with probable and negative reaction to MG were 51(57.3%) and 8(9%) respectively.
Their respective titer values varied from 249.67 to 735.61 and 1.80 to 63.094 respectively. It showed flock 3, 14 and 12 had the significant level of antibody titre for MG. In ninwe flocks have positive Mg titre, the. The result showed that flock 3, 14 and 12 had significantly higher (p<0.05) MG serum titer value which means these flocks were highly susceptible to MG infection with mean serum titer value 2475±179.45,1762±179.45 and 1247.480±179.45 respectively. Though there was different mean MG serum titer found in flock no 1,2,4to11,13,15,16to17. The MG titers were not significantly different (p<0.05). The flock no 18 and 19 had significantly lower (p<0.05) MG serum titer i.e. 29.73±179.45or 83.75 than the rest of the flocks.
It showed flocks with high MG titer had also high mortality. Similar observation had been reported by Kelly, 1994. The flock no. 18 and 19 had significantly low mortality as compared to rest of flocks. The low mortalities were due to regular use of antimycoplasmal drugs as CRD prevention program. Among different age groups 5-9 months age groups were most susceptible 33 % for MG infection
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