The Study Of F-strain Mycoplasma Gallisepticum Vaccine On Performance Of Commercial Broiler Breeders

Mycoplasma gallisepticum (MG) is a pathogenic organism that can infect chicken andcause chronic respiratory disease (CRD). In poultry the MG infection is spread verticallythrough infected eggs and horizontally by close contact. Chronic respiratory infectionsassociated with MG have a high prevalence throughout the world with significanteconomic impacts on the poultry industries, and are often associated with a concurrentvirus or bacterial infection, such as Newcastle’s Disease, Infectious Bronchitis, InfectiousBursal Disease, E. coil, Pasteurella, and Hemophilus species.Three different tools can beused to control MG-eradication maintained MG-free flocks, medication with variousantibiotics and vaccination. In the US all major breeder flocks generally remain free of MGthrough monitoring and eradication programs. However, eradication is proving hard toenforce and sustain, and it is inefficient to prevent and control MG by medication.Therefore, vaccination has become the main approach to controlling MG. The objective ofthe present study was to understand and explore influences of FMG vaccination beforelaying on productive and reproductive performance of commercial parent broiler chickenbreeders on a multi-age farm, through evaluating BW, laying performance, egg qualityparameters, fertility and hatchability of hatching eggs, and so on, throughout a completeegg laying cycle in Lingnan Yellow broiler chicken breeders inoculated with the FMGvaccine at1d and again at12wk of age, and characterizing possible physiological changes,including air-sac lesions and reproductive organ characteristics.3000parent broiler chicken breeders on a multi-age farm were randomly divided into2treatment groups that were either vaccinated with FMG (FMG-vaccinated group) or notvaccinated with FMG (FMG-free group). BW and BW of birds were determined at12,16,20,23,26,29,32,35,38,41,43,47and50wk of age. EP were determined started fromfrom the production of the first egg (22wk of age), until trial termination at50wk. Eggweight and feed conversion was determined at26,32,35,38, and43wk of age. Eggquality parameters, including eggshell strength, egg specific gravity, egg shape index,blood-meat spots, haugh units score, egg shell thickness, yolk:albumen ratio, percentageyolk, albumen, and eggshell weights, Moisture, ash, crude protein, crude fat, cholesterolcontent of egg yolk, and percentage fertility, hatchability, and second quality chicks weredetermined at26,32,43wk of age. Air sacs were examined and lesions were scored at20,32, and50wk of age. The number of mature ovarian follicles, histologies of ovary, and lengths, and histologies of the infundibulum, magnum, isthmus, uterus, and vagina weredetermined. The content of calcium, phosphorus, triglycerides, total cholesterol, totalprotein, urea nitrogen in serum were determined at32,35,38, and43wk of age.In the present study, it was found that percentages of FMG-positive birds maintained anespecially high level, and a decreasing tendency of percentages of VMG-positive birds wasshown in FMG-vaccinated group after vaccination. The FMG vaccine main effects werenot significant for BW. An increase in EP of broiler breeder hens in FMG-vaccinated groupduring peak of lay was compared to FMG-free group. Feed conversion of hens inFMG-vaccinated group was significantly less at32,35,38, and43wk of age. Eggs fromhens in FMG-vaccinated group had a significantly higher haugh units score at26wk of ageand had a significantly higher egg shell thickness and lower incidence of blood-meat spotsat32wk. Hatching eggs from hens in FMG-vaccinated group had a significantly higherhatchability. The mean lesion score of air-sac lesion of birds in FMG-vaccinated group wassignificantly less than FMG-vaccinated group，but there were no significant differencesbetween the different treatment groups for the number of maximum follicles. Uteruses ofhens in FMG-vaccinated group had a significantly longer length compared with FMG-freegroup at32wk of age. No significant differences were demonstrated between the treatmentgroups for histopathologic lesion scores within any of the tissues sampled and the parts ofbiochemical indexes in the blood. The results indicate that inoculation of commercialparent broiler chicken breeders with FMG vaccine before laying may prevent infection byfield MG, and facilitate productive and reproductive performance, including3-5%increasein EP,0.1-0.5decrease in feed conversion,1.25-1.75decrease in air-sac lesion,3.32increase in haugh unit,28%decrease in incidence rate of blood-meat spots,3.84%increasein hatchability and so on.