| Chicken proventriculitis is a chronic disease caused by multiple causes,which widely exists in various chicken flocks.The main manifestations of proventriculitis are chicken growth retardation,reduced feed conversion rate,and poor flock uniformity.On autopsy,the diseased chicken showed significant enlargement of the proventriculus,thickening of the proventriculus wall,and ulceration or bleeding of the proventriculus mucosa.The etiology of proventriculitis includes both non infectious and infectious factors,but currently most scholars believe that the disease is mainly caused by a combination of multiple factors.In this study,the pathogen of a clinical case of proventriculitis was detected.Simultaneously,the proventriculus of the infected chickens were homogenized and used as infection materials to infect the chickens.At the same time,the chickens were treated with excessive copper sulfate and moldy feed.The pathological models of proventriculitis constructed by these three treatment methods were compared and evaluated.After selecting the best modeling method among the three,a pathological model of proventriculitis was constructed to develop clinical prevention and treatment drugs for chicken proventriculitis.1.Diagnosis of clinical cases of proventriculitisThis study conducted histopathological examination and pathogen detection of the proventriculus of chickens clinically suspected of suffering from proventriculitis.Typical symptoms of proventriculitis on autopsy were seen including significant thickening of the wall of the proventriculus,multiple severe ulcers and significant bleeding spots in the proventriculus mucosa,flat or even disappeared proventriculus papilla,and so on.Microscopic observation showed that there were a large number of lymphocytes infiltrating in the glandular lobules of the diseased chicken,the structure of the glandular ducts in the areas with severe lymphocyte infiltration even disappeared,and the collecting sinuses were severely expanded and contained a large number of exfoliated necrotic cells.The dominant bacteria isolated from the proventriculus of diseased chickens were identified as Escherichia coli,and DNA and RNA were extracted from the proventriculus tissue of diseased chickens and PCR amplification was performed to detect 8 common viruses causing proventriculitis.The experimental results showed that only avian leukemia virus subgroup A(ALV-A)was positive.It is preliminarily determined that this batch of chicken proventriculitis is caused by mixed infection or secondary infection of Escherichia coli and avian leukosis virus subgroup A.2.Comparison of methods for establishing pathological models of chicken proventriculitisIn order to compare the effects of different methods for constructing proventriculitis models,40 healthy chickens were selected and raised to 7 days-old.They were randomly divided into four treatment groups.Each treatment group consisted of 10 healthy chickens,which were respectively divided into control group,model group I,model group II,and model group III.The control group was fed with normal feed.The model group Ⅰ chickens were fed with 500 mg/L Cu SO4 by gavage for 5 consecutive days.The model group Ⅱ chickens were fed with proventriculitis diseased chicken glandular gastric homogenate by gavage,After continuous intragastric administration for 5 days,and the model group III was conducted using moldy feed throughout the trial.At the age of 21 days,chickens were measured for weight related indicators and histopathological observation of the proventriculus.The results showed that the average body weight,average daily weight gain,and average bursal index of the model group were lower than those of the control group.The proventriculus in the model group showed symptoms of proventriculitis,including enlargement of the proventriculus,reduction or disappearance of the proventriculus papilla,and significant increase in the number of lymphocytes in the glandular lobules.The average proventriculus index and average proventriculus lesion score were higher than those in the control group;However,in the comparison of various model groups,it can be found that the average body weight and average daily weight gain in model group II decreased most significantly compared to the control group(p<0.05),and the chickens in this group experienced the most severe proventriculitis,characterized by high swelling of the proventriculus,edema of the isthmus,mucosal bleeding of the proventriculus accompanied by ulceration,reduced or even complete disappearance of the proventriculus papillae.In model I and model III groups,the ocular lesions of the proventriculus were relatively slight,characterized by a decrease in the number of mucosal proventriculus papillae.Histopathological lesion scores of the proventriculus showed that the average lesion score of the proventriculus in model group I and model group II was 1.83,which was considerably beyond than that in the control group,but lower than that in model group II(p<0.05).The main manifestations were a small amount of lymphocyte infiltration and a small amount of glandular cells metaplasia into glandular epithelial cells in some glandular lobules;The highest score in model group II was 3.50,which was significantly different from the average score of proventriculus lesions in other treatment groups(P <0.05).Specifically,most of the glandular lobules were infiltrated with lymphocytes or even lymph nodes,some of the collecting sinuses were severely dilated and contained a large number of exfoliated cell fragments,a large number of glandular cells in some glandular lobules are metaplasia into sinus epithelial cells,and the structure of the glandular lobules in the severely affected areas disappeared.Therefore,it can be determined that the use of proventriculus homogenate from diseased chickens to construct a pathological model of proventriculitis has the most significant effect.3.Research on drug prevention and treatment methods for chicken proventriculitisTo study the preventive and therapeutic effects of commercial veterinary drug combinations on proventriculitis,100 1 days-old Three Yellow broilers were selected and divided into control group,model group,treatment group I,treatment group II,and prevention group.Each group had two replicates,each with 10 replicates.After 1 daysold broilers were raised to 5 days-old,a prophylactic drug combination(0.25 g/L astragalus polysaccharide+0.5 g/L Bingshuang+0.25 g/L Xianweikang)was added to the drinking water of the prevention group.After 5 days,except for the control group,all the chickens in the experimental group were continuously gavaged with 0.5 m L of diseased chicken proventriculus homogenate for 5 days until 15 days-old to establish a pathological model of proventriculitis.Starting at the age of 16 days,treatment group I(0.5 g/L avian polyvitamin+0.6 g/L amoxicillin)and treatment group II(0.5 g/L astragalus polysaccharide+1 g/L Bingshuang+0.5 g/L Xianweikang)began to add drugs to drinking water for 5 days until 20 days-old.During the experiment,the daily food intake and daily weight gain of each group were recorded.At the age of 16 and 21 days,10 broilers were randomly selected from each group for measurement of body weight related indicators and histopathological observation of the proventriculus.The experimental results showed that the average body weight,average thymus index,and the average bursal index of the model was considerably lower than that of the prevention group(p<0.05),and the average proventriculus index was significantly lower than those in the model group(p<0.05).Although the average proventriculus lesion score did not reach a significant level compared to the model group,it was still significantly lower than the model group;The average body weight,average thymus index,and average bursal index of the treatment group I and II were significantly higher than those of the model group,while the average proventriculus index and average proventriculus lesion score were significantly lower than those of the model group.It can be seen that the growth status and immune level in the prevention group,treatment group I,and treatment group II are significantly higher than those in the model group,and the degree of proventriculitis lesions is also significantly lower than that in the model group.At the same time,the viral nucleic acid content in the proventriculus of the drug treatment group was lower than that of the model group.It might be suggested that the preventive and therapeutic formulations are beneficial to the prevention and treatment of proventriculitis,and can improve the growth performance and immune function of broilers.This study diagnosed a case of clinical proventriculitis caused by mixed infection of avian leukemia virus subgroup A and Escherichia coli;The effects of three methods for constructing pathological models of proventriculitis(excessive copper sulfate infection,proventriculus homogenate infection in diseased chickens,and moldy feed infection)were compared,and it was determined that the proventriculus homogenate infection method in diseased chickens had the best modeling effect among the three methods.It was also confirmed that adding 0.25 g/L astragalus polysaccharide,0.5 g/L Bingshuang and 0.25 g/L Xianweikang to drinking water can not only promote the growth of broilers,but also reduce the severity of proventriculitis in chickens,which play an important role in preventing proventriculitis.And adding 0.5 g/L avian multivitamin and 0.6 g/L amoxicillin to drinking water or adding 0.5 g/L astragalus polysaccharide,1 g/L Bingshuang and 0.5g/L Xianweikang to drinking water can effectively treat proventriculitis in sick chickens,which has certain reference value for the etiology,model establishment,and research on prevention and treatment methods of the disease. |
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