| With the scale and intensification of goat breeding,various diseases of goats are frequent due to improper feeding and management and imperfect immune prevention and control system.Among them,due to the weak body resistance of lambs,various diseases are highly likely to occur and lead to death,and the higher lamb mortality rate has become one of the greatest obstacles threatening the healthy development of largescale goat farms in China.Therefore,how to effectively prevent and control lamb diseases is an important issue to be solved urgently by goat breeding enterprises,goat disease prevention and control researchers and veterinarians.In this study,a large-scale goat breeding enterprise in Zigong City,Sichuan Province was used as the research object to analyze the epidemiology,incidence and mortality of common diseases of lambs in this farm during the actual production process,and to study the pathogenic species and characteristics of lamb respiratory diseases,in order to provide a scientific basis for the effective prevention and control of important diseases of lambs in this farm,and also provide a useful reference for the construction of lamb disease prevention and control system in other large-scale farms in China.The contents of this study and the study results are as follows:1.Investigation of main diseases of lambs in a large-scale goat farmIn order to analyze the main disease types and their risk factors of lambs in a largescale goat farm,lambs from a large-scale black goat farm in Sichuan Province were selected as the study subjects in this study.Through epidemiology,clinical diagnosis,anatomy of dead lambs and other methods,the incidence,mortality,mortality and daily feeding management of the main diseases,immunization procedures,biosafety prevention and control measures were statistically analyzed,and the possible causes and results of each disease were analyzed.The results showed that:(1)from February 2021 to February 2022,the total number of lambs in this farm was 554,the total number of dead lambs was 108,and the total mortality rate was 19.50%;(2)the main types of diseases prone to occur in lambs in this farm were respiratory diseases,lamb diarrhea,infectious pustulosis,and sarcoptic mange,with incidences of 54.48%,8.97%,2.91%,and 10.09%,respectively,and mortality rates of 26.75%,15%,7.69%,and 0%,respectively;(3)Serotype-specific molecular detection was performed on 81 strains of M.haemolytica and Pasteurella isolated in this field,and the results showed that: among the M.haemolytica serotypes,A2 serotype was the highest,accounting for 76.5%;followed by serum A6 type,accounting for 9.8%,while serum A1 type accounted for 7.4%,indicating that the M.haemolytica infected in this field was mainly serotype A2 as the dominant serotype;10strains of Pasteurella multocida,all of which were capsular serotype D.(4)The farm is not sound in the biosafety system,and lacks the main disinfection measures for the incoming and outgoing personnel,the low frequency of disinfection and the prevention and control of epidemic diseases in imported sheep.In this study,the types,morbidity and mortality of the main diseases of lambs in this farm were systematically analyzed,and the results showed that respiratory diseases were common diseases of lambs in this farm and the main causes of lamb death in this farm.The results of this study also laid the foundation for this study to further determine the causes of respiratory diseases in lambs in this farm.2.Detection,isolation and identification of the main pathogens of the respiratory tract in lambs and drug sensitivity testsIn order to understand the main pathogens present in the respiratory tract of lambs in this large-scale goat farm,in this study,samples were collected from lambs with respiratory diseases,and then molecular detection of the main respiratory disease pathogens was performed using specific PCR methods.At the same time,each sample was isolated and identified for the main pathogens,and the serotypes of the isolated strains were identified to evaluate the susceptibility to commonly used drugs.The results showed that:(1)The highest detection rate of Mannheimia haemolytica was found to be 61.5%,Pasteurella multocida was found to be 10%,and Mycoplasma ovipneumoniae was found to be 42.9% by specific PCR.No Mycoplasma filiformis or goat parainfluenza III virus infection was found in this study;(2)81 strains of Mannheimia haemolytica and 10 strains of Pasteurella multocida were isolated,indicating that the main pathogens of respiratory diseases infected in this large-scale farm were Mannheimia haemolytica,Pasteurella multocida and Mycoplasma ovipneumoniae;(3)Serotype-specific molecular detection was performed on 81 strains of Mannheimia haemolytica and Pasteurella isolated in this field,and the results showed that A2 serotype accounted for 76.5% of Mannheimia haemolytica serotypes,which was the highest;followed by serum A6 type,which accounted for 9.8%,while serum A1 type accounted for 7.4%,indicating that serotype A2 was the dominant serotype of Mannheimia haemolytica infected in this field;10 strains of Pasteurella multocida,all of which were capsular serotype D.(4)Eighty-one strains of Mannheimia haemolytica isolated in this field showed high sensitivity to ofloxacin,cefotaxime,chloramphenicol,flufenicol,ampicillin,cephalexin as well as tetracycline.It is resistant to penicillin,streptomycin and erythromycin to a certain extent,and Pasteurella multocida is highly sensitive to most drugs in addition to erythromycin and lincomycin.In conclusion,this study provides a theoretical basis for reducing the morbidity and mortality of lambs in this large-scale goat farm by investigating the main diseases existing in lambs and studying the main pathogens existing in the respiratory tract,and also lays a scientific foundation for the formulation of epidemic disease prevention and control in large-scale farms. |
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