| Actinobacillus pleuropneutnoniae(APP) is the etiological agent of porcine contagious pleuropneumoniae (PCP).PCP is one of important respiratory diseases in intensive pig farms, which continues to have a worldwide economic significance. The peracute or acute form may lead to a lot of pig death; the subacute or chronic form may also cause severe economic losses to the swine industry by lowering the speed of growth and the conversion efficiency of feed. Its existence and prevalence gets more and more serious day and day in recent years. By far, it happens in many regions of our country.15 serotypes of APP have been recognized by far. There is no or weak cross relation in different serotypes, which brings many troubles to diagnosis and prevention of this disease. APP may easy obtain resistance to antimicrobials, which can lead to pigs that were sensitive to APP death fast by pneumorrhagia. For this reason, studying on serology of PCP, selecting susceptive antimicrobials against APP, exploring control of PCP with drugs and vaccine can help us prevent and control it.By using indirect hemagglutination assay (IHA), 928 non- vaccinated serum samples from partial intensive pig farms in Luoyang area were tested for antibody against PCP. The results were as follow: 30.39 %( 282/928) checked sera antibody titers were >1:8 which was regarded as positive. The positive rates in sows, breast-feeding piglets (20-day~old),postweaning piglets (40-day-old),growing pigs(80~ 100-day-old), growing pigs(l 50~ 180-day-old) were 61.59%(101/164), 42.46%(76/179),7.07%(14/198), 30.05%(64/213) and 15.52%(27/174)respectively. The geometrical average value of titer of positive pigs were 1:69.01,1:15.29, 1:11.89, 1:26.92, 1: 18.65 respectively.In vitro the susceptibility of 18 isolated Actinobacillus pleuropneumoniae strains to 12 antimicrobial agents was tested. The result showed that the sequence of resistance to antimicrobials was Streptomycin, Clindamycin >Norfloxacin>Penicillin QKanamycin, Ciprofloxacin >Ampicillin, Gentamicin,Cefazolin> Florfenicol > Amikacin, Ceftriaxone. The susceptible rates of 18 isolated Actinobacillus pleuropneumoniae strains to Florfenicol, Amikacin, Ceftriaxone were 77.78%, 83.33% and 83.33% respectively , which are the first to be chosen in control of PCP.This study also was conducted to compare the effect of control using Florfenicol with that of Amikacin. The result showed that gross efficiency were 95.71% and 90.37% respectively(P<0.01). The efficiency of the control group was 66.87%.There was extreme significantly difference between the experiment groups and the control group(PThe late-pregnant sows (about 84 days) were vaccinated with an inactivated trivalent vaccine containing serotypes 1, 3, 7 of APR The geometrical average value of antibody titer of piglets bred by these sows were 1:35.10, 1:19.70, 1:12.10 and 1:10.08 respectively at 20-day-old, 40-day-old , 60-day-old, 80-day-old , which were higher than that of piglets bred by non- vaccinated sows(P<0.05 or P<0.01).Postweaning piglets bred by non-vaccinated sows were vaccinated at 40-day-old , the geometrical average value of antibody titer were 1:38.5,1:24.25,1:18.80 respectively at 60-day-old,80-day-old ,100-day -old , which were higher than that of non- vaccinated postweaning piglets (P<0.01). |
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