Detox Dynamics and Reproductive Performance of Langya Chickens Infected with ALV-J
[Background]China is rich in local chicken resources.The spread of J subtype avian leukemia (AL-J) in local chicken breeds has restricted the conservation,development and utilization of local chickens.[Objective]By analyzing the infection dynamics of ALV-J positive Langya chickens rooters,the detox dynamics of ALV-J positive Langya chickens hens from pre-opening to self-propagation,and the effects of ALV-J on reproductive performance (fertilization rate,hatching rate,egg number and egg production decline rate after peak laying),this study provided a reference for the AL-J purification of local chickens and was helpful to the protection,development and utilization of local chicken breeds in China.[Method]For the ALV-J negative and positive Langya chicken hens,the blood virus isolation and cloacal swab P27 antigen detection were performed every 30 days starting from the 145th day of age.Starting from the age of 330 days for the ALV-J positive rooster group,the semen virus isolation and cloacal swab P27 antigen detection were performed every 4 days.The semen quality and DNA damage degree of ALV-J negative and positive roosters were determined,as well as egg quality of ALV-J negative and positive hens.The insemination test of ALV-J negative and positive male and female chickens (G1 group:positive male chicken × positive hen;G2 group:positive male × negative hen;G3 group:negative male × positive hen;G4 group:negative male chicken × negative hen) was carried out,and the fertilization rate and hatching rate of each group of eggs were counted.The average number of eggs laid per week from the start of laying to 43 weeks of age in ALV-J negative and positive hen groups as well as the egg production decline rate after peak egg production were analyzed.[Result]Studies on the detox dynamics of ALV-J positive roosters showed that semen and cloacal swabs were not completely consistent each test,with some positive chickens testing positive only in semen or cloacal swabs,and five out of 20 positive cocks testing negative in consecutive tests.The detox dynamic results of ALV-J positive hens showed that the isolation and detection rate of blood virus was the lowest at 205 days (78.16％) and the highest at 325 days (90.79％),and gradually increased at 265,295 and 325 days,and was similar at 295 and 325 days.Comparison results of the blood virus isolation and cloacal swab detection of ALV-J negative and ALV-positive chicken flocks showed that cloacal swab detection had a high false positive and missed detection rate.There was no significant difference in routine semen quality and DNA damage detection (DFI) between ALV-J negative and ALV-J positive roosters (P>0.05).The egg quality measurement results of ALV-J negative and ALV-J positive hens showed that there were extremely significant differences in egg weight,Hastelloy units,yolk weight,and albumen height (P<0.01).There was no significant difference in eggshell strength,egg shape index,egg yolk color,and eggshell thickness (P>0.05).The results of the breeding insemination experiment showed that there was no significant difference in the fertilization rate and hatchability of ALV-J-positive male eggs from those of negative chickens.The fertilization rate and hatching rate of chicken eggs were significantly lower than those of negative chickens,and there was no significant difference in the fertilization rate and hatching rate of ALV-J positive male and female chicken eggs.Analysis of the egg production performance of ALV-J negative and positive groups showed that the average number of eggs laid per week from the beginning of laying to 43 weeks of age in the ALV-J positive group was significantly lower than that in the ALV-J negative group (P<0.01).The egg production decline rate after the egg production peak (0.016) was lower than that of the ALV-J positive group (0.033).[Conclusion]The semen of ALV-J positive rooters has been tested negative for many times,which could be used as breeding roosters in local chicken breeds with high ALV-J positive rate.According to the results of ALV-J detox dynamic study of ALV-J infection in Langya chickens combined with self-propagation time,the best time period for ALV-J blood virus isolation and detection was around 300 days of hen age.Cloacal swab ALV testing had extremely high false positive and missed detection rates and was not recommended.ALV-J infected hens significantly reduced the number of eggs laid,the decline rate of egg production accelerated after the peak laying,and significantly reduced egg weight,yolk weight,protein height and other indicators,leading to a decrease in fertilization rate and hatching rate.The research results provided data support for the formulation of ALV-J purification plan for Langya breeder chickens.
万方数据
维普
