| The economic losses caused by calf pneumonia caused by Mycoplasma bovis are very large and showing an increasing trend year by year.However,so far,there is no detailed epidemiological information about Mycoplasma bovis in China.In this context,the aim of this study was to assess the infection rate and incidence of Mycoplasma oxalyx,a common pathogen of calf pneumonia in Chinese pasture.A total of 17280 nasal swabs were collected from 30 farms in six regions in China during 2013-2015.A total of 17280 nasal swabs were collected,including 328 lung and lung tissues died from pneumonia.These samples for isolation and identification of pathogens,including Mycoplasma positive infection rate was 47.5%,Pasteurella multocida positive infection rate was 0.7%,mannheimiahaemolytica alone positive infection rate was 0.5%,single rhinotracheitis virus positive rate was 22%,bovine viral diarrhea virus positive infection rate 28%,bovine parainfluenza type 3 virus positive infection rate was 12%.The bovine mycoplasma and Pasteurella multocida,Pasteurella haemolytica,infectious bovine rhinotracheitis virus,bovine viral diarrhea virus,bovine parainfluenza virus type 3 infection rate were 0.42%,0.3%,14%,18%,3.4%,Mycoplasma bovis and infectious bovine rhinotracheitis virus,bovine viral diarrhea virus mixed three the infection rate was 2.8%.The mixed infection rate of Mycoplasma bovine and Pasteurella multocida and mantmus haemolyticus was 1.5%.The rate of mixed infection of six pathogenic bacteria was 0.0035%.Calf pathogens including Mycoplasma bovis,Pasteurella multocida,hemolytic mansoni Salmonella BVDV;most pathogens,the peak incidence of age related stressors,calves appeared at 20-40 days old first calf pneumonia incidence peak,calf pneumonia incidence rate is as high as 62.49%,second of the peak incidence occurs in weaned calves between before and after 60-80 days of age,the incidence rate was 59.44%.However,with the growth of day age,the immune system of calves gradually improved and the mortality rate decreased from the initial 2.11% to 1.48%.From the epidemiological results,calf pneumonia incidence is mainly infected by Mycoplasma bovis pneumonia caused by calf death is mainly caused by various pathogenic bacteria mixed infection,data shows that due to Mycoplasma bovis colonization in the respiratory system,chronic consumption of body function,resulting in decreased body resistance,thus creating conditions for other pathogens.Against this background,from January 2016 to June 2017,Mycoplasma bovis isolated from pasture was used to make inactivated vaccine,and its bacterial content was 1011cfu/ml.From the immune results,14 days of the six areas of pasture calves after the first immunization,a calf antibody titer can reach 72% at 1:32,in a free 28 days after the 67% calves titer of 1:64;at the same time the 2 immunization,two free after seventh days,93% calves antibody titer can reach 1:128,two free 14 days after the antibody titer stabilized to 28 days after two free,there are 98% calves antibody titer reached 1:128.After that,the titer of calves was continuously monitored.At 75 days of age,the antibody of calves began to decline,maintained at 1:64-1:128,and the titer of antibody decreased to 1:64-1:32 at 90 days old.The results showed that the two immunized calves could be maintained to 90 days of age,and two large stresses had a good protective effect during this period.By controlling the immune group of cattle mycoplasma infection rate comparing immune group and experimental group of other pathogen infection rate,the results showed that through the immune and immune group and control before and after nasal swabs collected from group detection results,the detection rate of primary branch of bovine growth rate in 60 d,120d,200 D,300D,400 d,500D compared with 15 d that the immune group were decreased by 3.89%,3.89%,3.33%,2.78%,2.78% and 0;the control group increased by 3.33%,5.56%,6.67%,3.89%,8.89%,0;an increased value increased by 7.22%,9.44%,10%,6.67%,11.67%,0.From the immune group and control group were divided into calf calf results and the incidence situation,Mycoplasma bovis vaccine of bovine mycoplasma infection play a good preventive effect at the same time,also reduce the intrusion of other pathogenic bacteria,which is the most obvious effect on viral pathogens,the detection rate in the immune group there,but is much lower than that of the control from this group,probably results from the side that can play an important role in Mycoplasma bovis pneumonia in calves. |
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