The relationship of Cryptosporidium sp. infection of the bursa of Fabricius, intestinal tract, and respiratory system of chickens in Georgia, 1974-1988

During 1974-1984, cryptosporidiosis was diagnosed in slightly more than 1% (63/6050 = 1.04%) of histopathology reports on chickens and turkeys made at two Georgia diagnostic laboratories. During 1985-1988, cryptosporidiosis was diagnosed in almost 6% (157/2622 = 5.99%) of histopathology reports on chickens and turkeys made at the two laboratories. Intestinal and respiratory Cryptosporidium sp. infections have increased significantly (p less than 0.01) with time. During the same period, there was no statistical pattern for bursa of Fabricius Cryptosporidium sp. infections, and there was no relationship between the incidence of bursal infections and the incidence of either respiratory or intestinal infections.     

Light-microscopic lesions associated with naturally occurring bursal cryptosporidiosis in chickens

Information concerning histologic significance of naturally occurring bursal Cryptosporidium sp. infection in chickens was obtained by retrospective examination of histopathology reports and clinical data from histology accessions received during 1986. Cryptosporidiosis was diagnosed in 197 bursas. In two-thirds of the accessions, more than 50% of the examined bursas were infected with Cryptosporidium sp. The histologic morphologic lesion diagnosis for Cryptosporidium sp.-infected bursas most often was marked diffuse chronic-active superficial purulent protozoal bursitis with mucosal epithelial hyperplasia. Our study clearly indicates that Cryptosporidium sp. is associated with inflammation and disturbed growth in chicken bursas. Additionally, our data indicate that Cryptosporidium sp. infection is not dependent on bursal damage attributable to other agents, including infectious bursal disease virus.     

A survey for parvovirus-like virus (so-called chick anemia agent) antibodies in broiler breeders

A prospective study to survey for the presence of parvovirus-like virus (PVLV; so-called chick anemia agent) antibody in broiler breeder pullets in Georgia, North Carolina, and Florida was conducted by collecting serum samples from 52 breeder flocks that ranged in age from 1 day to 55 weeks old. Results indicated that PVLV infection was widespread. Ninety-eight percent (51/52) of chicken flocks and 62% (530/861) of chickens had PVLV antibody. Rates of antibody-positive chickens among flocks ranged from 0% to 100% and averaged 76%. Upon initial examination, the percentages of chickens positive for PVLV appeared evenly distributed with respect to several convenient age groups and geographic locations. However, compared with young chickens (less than or equal to 19 weeks old), markedly significantly lower proportions of positives were present among chickens more than 19 weeks old (P = 0.00001) or chickens 30 weeks old or more (P = 0.000004). Also, there were significant (F = 7.7, df = 3/827, P less than 0.001) differences among the rates of PVLV antibody in chickens among various companies. The relatively high rate of PVLV antibody among broiler breeder chickens helps explain the low incidence of clinical disease among their offspring.     

Intestinal cryptosporidiosis in chickens

In a retrospective examination of histopathology reports from Aug. 1, 1985, through Sept. 31, 1987, 10 cases of small- or large-intestinal cryptosporidiosis (not epithelial cryptosporidiosis of the bursa of Fabricius) were found in chickens. Infection was evenly distributed among young chickens. Incidence of intestinal cryptosporidiosis increased during 1987. Although all infected birds were clinically ill, signs or gross lesions of intestinal disease were not always present. In all cases, mild to marked histologic lesions were associated with Cryptosporidium sp.; however, intestinal tracts were not cultured for other infectious agents. The numbers of Cryptosporidium sp. and character of inflammatory response were not significantly correlated. A difference (P = 0.01) among intestinal segment (small vs. large) infection with Cryptosporidium was seen. Light-microscopic appearance and organ distribution of Cryptosporidium sp. suggest that in addition to C. baileyi, other Cryptosporidium species infect chickens. Until the diagnostic procedure for outbreaks of gastrointestinal disease in poultry routinely includes histopathology, fecal flotation, and virus, bacteria, and chlamydia cultures, and until species of Cryptosporidium are isolated, identified, reported, and investigated experimentally, the importance of intestinal cryptosporidiosis in chickens will remain unknown.     

Efficacy of halofuginone lactate in the prevention of cryptosporidiosis in dairy calves

To evaluate the efficacy of halofuginone lactate (Halocur; Intervet) when used prophylactically against cryptosporidiosis in dairy calves, 513 Holstein heifer calves were randomly distributed between two experimental groups. Those in the treatment group (n=259) received 0.1 mg halofuginone base per kg bodyweight daily in a 10 ml solution, for the first seven days following birth, while those in the control group (n=254) received an equal volume of a placebo solution. Faecal samples were collected weekly from all calves until three weeks of age to test for Cryptosporidium oocysts and to assess the diarrhoeal status. Growth parameters of the calves were also recorded at approximately four months of age. Calves that received halofuginone were significantly less likely to shed Cryptosporidium oocysts during the course of the study than placebo-treated calves (odds ratio 0.6, 95 per cent confidence interval 0.4 to 0.9, P=0.009). Mean growth measurements of calves in the treated group were consistently higher than those of the control calves (hipometer-derived P=0.052, wither height P=0.097) and mortality was lower in the treated group (P=0.07). However, these differences were not statistically significant (P>0.05). No association was found between the prophylactic use of halofuginone and the incidence of calf diarrhoea.     

Renal Cryptosporidiosis (Cryptosporidium baileyi) in specific-pathogen-free chickens experimentally coinfected with Marek's disease virus

Renal Cryptosporidiosis was experimentally induced during a study to investigate the pathogenicity of Cryptosporidium baileyi in specific-pathogen-free (SPF) chickens coinfected with Marek's disease virus (MDV). Cryptosporidium baileyi was administered orally at 4 days of age to chickens previously infected at hatching (day 0) with the HPRS 16 strain of oncogenic MDV. Three control groups received MDV at hatching, C. baileyi on day 4, or placebo consisting of distilled water. Renal cryptosporidiosis lesions were induced in the group coinfected with MDV and C. baileyi. The kidneys were markedly swollen and pale, with visible urate crystals in the ureters and surface tubules. Oocysts of C. baileyi were demonstrated in six of seven cases tested by a scoring method with modified Sheather's sugar solution on renal tissue scrapings and were confirmed in three cases by histologic examination of paraffin-embedded kidney sections. Histologic study also revealed subacute interstitial nephritis, acute ureteritis, and attachment of cryptosporidia on the epithelial cell surface of the ureters and collecting ducts, collecting tubules, and distal convoluted tubules. Various developmental stages of the parasite were present in the kidney sections. To our knowledge, this is the first report of experimentally induced renal cryptosporidiosis in SPF chickens coinfected with MDV.     

Comparison of histopathology to the direct immunofluorescent antibody test for the diagnosis of infectious laryngotracheitis in chickens.

Histopathology and direct immunofluorescent antibody (DIFA) tests were compared for diagnoses of infectious laryngotracheitis (ILT) in 144 cases of spontaneous respiratory disease in chickens presented to the Georgia Poultry Laboratory during 1988. For the 48 cases in which ILT was diagnosed, correct histologic diagnoses were made 100% (48/48) of the time and correct DIFA diagnoses were made 96% (46/48) of the time. For the 96 cases in which ILT was not diagnosed, correct histologic and DIFA diagnoses were made in every case. A Kappa test showed that DIFA was as effective as histopathology for the diagnosis of ILT in chickens (P = 0.0). It was concluded that increased use of DIFA could be instrumental in the abatement of ILT in chickens.     

Relationship of common avian pathogen antibody titers in so-called chicken anemia agent (CAA)-antibody-positive chicks to titers in CAA-antibody-negative chicks.

Antibody titers for infectious bursal disease virus (IBDV), infectious bronchitis virus, Newcastle disease virus, and reovirus from chicks with chicken anemia agent (CAA) antibodies were compared with antibody titers from their CAA-antibody-negative counterparts. These comparisons were made in 396 chickens that were 1 day, 2 weeks, 8-9 weeks, 10 weeks, 17 weeks, or 29-32 weeks old. Only one serum sample was collected from any given chick or chicken. There were no significant differences between the antibody titers at any age for any antigen, with one exception: at 29-32 weeks, the IBDV titers were higher (t = 2.62, df = 142, P less than 0.01) in chickens with CAA antibody. Although not at all likely, we believe that the observation of high IBDV antibody titers in CAA-antibody-positive chicks could have been a spurious one.     

Performance and oocyst shedding in broiler chickens orally infected with Cryptosporidium baileyi and Cryptosporidium meleagridis

To study effects of experimental cryptosporidiosis, broiler chickens were infected per os with 5 x 10(5) oocysts of Cryptosporidium baileyi and Cryptosporidium meleagridis. In the first experiment, chickens were infected with oocysts of C. baileyi at the age of 7, 14, and 21 days. In the second experiment, chickens were infected with oocysts of C. baileyi, C. meleagridis, or both cryptosporidial species at the age of 7 days. Although clinical signs of infection were apparent, neither final live weight nor mortality was significanty influenced in chickens infected with a single Cryptosporidium species. In chickens infected with C. meleagridis, the growth retardation was observed in the 2-wk period after infection. The compensatory growth, however, started when the oocyst shedding had ceased. The number of oocysts in excreta specimens of chickens infected with C. meleagridis was two to three times lower than in excreta of chickens infected with C. baileyi. Chickens infected with both C. baileyi and C. meleagridis (5 x 10(5) oocysts of each) had significantly lower final live weight and worse feed efficiency than chickens of other groups. Concurrent infection did not influence individual C. baileyi or C. meleagridis oocyst shedding.     

广东鸡,鸭隐孢子虫种类鉴定与致病性研究

从有患轻微呼吸道症状的鸡和鸭的粪便中分离到隐孢子虫卵囊，并在其组织切片中观察到隐孢子虫。根据卵囊的形态和大小、虫体寄生部位，确定鸡、鸭均为贝氏隐孢子虫感染。用上述鸡、鸭粪便中分离的卵囊，分别经口感染２日龄鸡和鸭各１５只以探索其致病性。感染鸡出现明显呼吸道症状，将引起死亡，气管、支气管、气囊、肺和法氏囊出现大体与显微病变。感染鸭则症状和病变都较鸡轻。结果表明：鸭对贝氏隐孢子虫感染的抵抗力比鸡强。     

Muscle protein turnover and tenderness in broiler chickens fed cimaterol

To investigate the impact of cimaterol (CIM) on muscle protein turnover, carcass and muscle composition, muscle cathepsin B + L activity and meat tenderness, 21-d-old broiler chickens (n = 88) were assigned to dietary treatments of either 0 or 1 ppm CIM. Fractional synthesis rates (FSR), fractional accretion rates (FAR), proximate composition and collagen content were determined in the breast muscle (BM); pectoralis major) and a group of leg muscles (LM; gastrocnemius and peroneous longus) from groups of six birds per treatment within each of two time periods (age = 38 or 56 d). Whole body composition, serum hydroxyproline content and BM cathepsin B + L activity also were measured. Fractional degradation rates (FDR) were calculated as the difference between FSR and FAR. Feeding CIM increased (P less than .01) whole body protein content. Weights of LM and percentage of body weight as BM and LM were increased (P less than .05) when CIM was included in the diet. Although FSR was not significantly reduced by CIM feeding it decreased (P less than .05) with increasing age. Due to decreases in FAR, FDR thereby was reduced by CIM 31.5% and 11.9% in BM and 38.2% and 37.4% in LM at 38 d and 56 d of age, respectively. Cathepsin B + L activities also were reduced 33.6% (P less than .01) and shear forces were increased by 41% (P less than .05) by CIM feeding. For chickens fed CIM, the correlation between cathepsin B + L activity and shear force was -.63 (P less than .01). Feeding CIM improved carcass leanness and muscling due to reductions in FDR and proteolytic enzyme activity. Feeding CIM also reduced meat tenderness.     

目标取样法和扫描取样法在圈养黑熊行为研究中的比较

应用目标取样法和扫描取样法同时对5只圈养黑熊(Ursus thibetanus)的15种行为进行了观察和记录,并对两种方法所得结果进行比较和讨论,评估两种方法在动物行为学研究中的可靠性。结果表明:两种方法所得的行为实际频次间存在显著差异(χ2=4.388,P=0.036,df=1),相对频次间无显著差异(χ2=0.468,P=0.494,df=1);行为持续时间的长短是影响两种方法所得结果间差异的主要因素,其与相对偏差值(Rela-tive Deviation,RD)之间存在显著的负相关关系(实际频次:r=-0.900,P=0.000,df=13;相对频次:r=-0.898,P=0.000,df=13);两种方法所得行为发生频次间存在显著正相关关系(r=0.965,P=0.000,df=13);扫描取样法所得行为间的差异性分析结果中70.5%与目标取样法的分析结果一致,29.5%存在分歧,且在分歧组中,参与差异性分析的两种行为的持续时间之差极显著大于一致组(χ2=10.082,P=0.001,df=1)。     

Humoral and cell-mediated immune responses in chickens with infectious bursal disease

Primary and secondary immune responses to Newcastle disease virus (NDV) was evaluated in chickens infected with infectious bursal disease virus (IBDV) at one and 28 days of age. The geometric mean primary hemagglutination-inhibition antibody titers (GMT) of chickens infected with IBDV at one day of age was significantly lower (P less than or equal to 0.01) than those infected at 28 days of age. Infection with IBDV had no influence on secondary immune response to NDV. The effect of IBDV infection at one day of age on the cell-mediated immunity of chickens was evaluated by skin allograft acceptance or survival time. There was no significant difference between the percentage of grafts accepted in IBDV infected and noninfected control chickens. However, the mean graft survival time in the IBDV infected chickens was significantly longer (P less than or equal to 0.05) than those in the control group. This suggested a suppression of cell-mediated immunity due to IBDV infection.     

饲粮粗蛋白质水平对鲁西斗鸡生产性能及蛋品质的影响

本试验旨在研究饲粮不同粗蛋白质水平对26～41周龄的鲁西斗鸡生产性能及蛋品质的影响。试验选用26周龄(1.952±0.288)kg健康的鲁西斗鸡200只,随机分为4组,每组5个重复,每个重复10只。试验采取单因素试验设计,4个饲粮粗蛋白质水平依次为:14.0%、15.5%、17.0%和18.5%,各组均限饲,且投料量一致。试验期为16周。结果表明:在鲁西斗鸡产蛋期(26～41周龄),饲粮粗蛋白质水平对平均蛋重没有显著影响(P>0.05)。在试验前期(26～29周龄),饲粮粗蛋白质水平对平均周产蛋量、产蛋率和料蛋比均无显著影响(P>0.05);在试验中期(30～37周龄),30～33周龄17.0%饲粮粗蛋白质水平组平均周产蛋量显著高于其他各组(除30～31周龄15.5%饲粮粗蛋白质水平组外)(P<0.05),30～31周龄和36～37周龄产蛋率显著高于14.0%组和18.5%组(P<0.05),32～35周龄产蛋率显著高于15.5%组(P<0.05),但是各组间30～37周龄料蛋比差异不显著(P>0.05);在试验末期(38～41周龄),18.5%饲粮粗蛋白质水平组平均周产蛋量显著高于其他各组(P<0.05),产蛋率显著高于14.0%组和15.5%组(P<0.05),料蛋比显著低于15.5%组(P<0.05)。此外,33周龄时,随着饲粮粗蛋白质水平提高,蛋黄颜色有下降趋势(P=0.09);41周龄时,17.0%和18.5%饲粮粗蛋白质水平组蛋白高度和哈氏单位显著高于14.0%组和15.5%组(P<0.05)。综合以上结果,鲁西斗鸡产蛋期适宜的饲粮粗蛋白质水平:前期(26～29周龄)为14.0%;中期(30～37周龄)为17.0%;后期(38～41周龄)为18.5%。     

Effects of Low Crude Protein Level Diet Based on Corn-Peanut Meal on Growth Performance and Nitrogen Utilization of Chinese Yellow Chickens at 1 to 21 Days of Age北大核心CSCD

本试验旨在研究基于玉米-花生仁饼型低粗蛋白质(CP)水平饲粮对1~21日龄黄羽肉鸡生长性能和氮利用率的影响。选取1日龄快速型岭南黄羽肉鸡1920只(公母各占1/2),公、母鸡各按体重一致原则随机分为4组(每组6个重复,每个重复40只)。4个组的饲粮CP水平分别为22.5%、21.5%、20.5%和19.5%。试验期21 d。结果表明:1)饲粮不同水平CP和性别对21日龄肉鸡末重和1~21日龄平均日增重(ADG)均有显著影响(P<0.05)且具有显著交互作用(P<0.05);22.5%CP组和21.5%CP组ADG均显著高于20.5%CP组和19.5%CP组(P<0.05),饲粮CP水平对肉鸡ADG的影响具有显著线性效应(P<0.05)。22.5%CP组公鸡ADG最高,显著高于其他3个CP水平组(P<0.05),21.5%CP组公鸡ADG也显著高于20.5%CP组和19.5%CP组(P<0.05);22.5%CP组和21.5%CP组母鸡ADG均显著高于19.5%CP组(P<0.05)。2)饲粮不同水平CP对肉鸡料重比(F/G)有显著影响(P<0.05)且具有显著的线性效应(P<0.05);22.5%CP组F/G最低,显著低于其他3个水平CP组(P<0.05);21.5%CP组F/G显著低于19.5%CP组(P<0.05)。3)饲粮不同水平CP均对肉鸡氮利用率有显著影响(P<0.05)。21.5%CP组肉鸡氮利用率最高,显著高于其他3个水平CP组(P<0.05),19.5%CP组氮利用率也显著高于20.5%CP组(P<0.05)。由此可见,以玉米-花生仁饼为基础饲粮,低CP水平饲粮中尽管补充添加了晶体氨基酸,但是还是会影响公鸡生长。1~21日龄快速型岭南黄羽肉鸡母鸡饲粮CP水平可以降低1~2个百分点。建议将公、母鸡分开饲养,以实现对其营养的精准调控,提高氮利用率,降低氮排放。     

Genetic resistance to Heterakis gallinarum in two chicken layer lines following a single dose infection

Groups of White Leghorn and New Hampshire male and female chicks were reared under helminth-free conditions and divided into two groups at an age of 8 weeks. One group was artificially infected with 100 embryonated Heterakis gallinarum eggs, while the other group was kept as uninfected control. After 8 weeks all animals were harvested and worm burden was established. Maximum of 60 worms per bird randomly selected were measured for length. Body weights were recorded at 8 and 16 weeks of age. Total worm burden was significantly (P<0.0001) higher in infected males than in infected females. Furthermore, White Leghorns showed a significantly (P=0.011) higher number of worms when compared with New Hampshire animals. Average worm lengths were not significantly different between the breeds (P=0.155) and sexes (P=0.062). Correlations between worm burden and worm length was 0.08 (P=0.140). The daily weight gains between 8 and 16 weeks of age of the infected animals were significantly (P=0.038) lower when compared with the control group. There was no significant correlation between daily weight gain and worm burden. The estimated heritabilities for logarithm (ln) worm burden were 0.41 (S.E.+/-0.086) in White Leghorn and 0.31 (S.E.+/-0.126) in New Hampshire, respectively. Based on the estimated heritabilities it is possible to select for H. gallinarum resistance in both genetically distinct chicken breeds. This approach may be of importance for chickens kept in floor husbandry systems.     

Comparative efficacy of enrofloxacin, oxytetracycline, and sulfadimethoxine for the control of morbidity and mortality caused by Escherichia coli in broiler chickens

The purpose of the present study was to compare the ability of enrofloxacin, oxytetracycline, and sulfadimethoxine to reduce morbidity and mortality caused by Escherichia coli (colibacillosis) in broiler chickens. The chickens were raised in 80 pens (20 birds per pen) with 20 pens representing each treatment group under simulated commercial conditions that produced a colibacillosis challenge scenario. Each group of 20 randomized pens (replicates) was given one of four water treatments. Chickens that received enrofloxacin had significantly less mortality (P < 0.01), lower average gross pathology (colibacillosis) scores (P < 0.01), and better feed-conversion ratios (P < 0.05) than did chickens that received either oxytetracycline or no medication. Chickens that received enrofloxacin had significantly less mortality and lower pathology scores than those that received sulfadimethoxine and numerically lower feed conversion than the sulfadimethoxine group. Results from the present study show that enrofloxacin is superior to oxytetracycline and sulfadimethoxine for the control of morbidity and mortality caused by E. coli in broiler chickens. Our findings will help veterinarians choose and prescribe the most efficacious antimicrobial when treating colibacillosis.     

Influence of in ovo administered Cryptosporidium baileyi oocyst extract on the course of homologous infection

In order to evaluate the effect of in ovo vaccination on avian cryptosporidiosis, two doses (1 and 10microg) of Cryptosporidium baileyi oocyst extract (OE) were injected into the amnionic sac of embryonated, specific pathogen-free chicken eggs. After hatching these birds as well as infected controls (IC) were inoculated with 8x10(5) C. baileyi oocysts at 10 days of age. Another group of chickens remained uninfected (UC). Faecal oocyst shedding was measured every second day, and weekly ELISAs were performed to monitor seroconversion. Those chickens that received OE during embryogenesis showed dose-dependent shift in their oocyst shedding, with higher oocyst output of OE1 and OE10 birds compared to IC ones. The patency was significantly longer in the OE10 group than in IC or OE1. ELISA results showed low seroconversion of OE1 and OE10 chickens prior to homologous challenge. Challenge infection resulted in antibody levels without significant difference between IC, OE1 and OE10 groups. These data suggest that in ovo vaccination with C. baileyi oocyst extract does not promote immune response, moreover, it may impair immunity and thus delay the clearance of cryptosporidia from chickens.     

Studies of reticuloendotheliosis virus-induced lymphomagenesis in chickens

Seventy-three percent of chickens inoculated with the chick syncytial strain of reticuloendotheliosis virus (REV) at hatching developed lymphomas by 39 weeks of age. Neonatal treatment with cyclophosphamide or surgical bursectomy at 2, 4, 8, or 12 weeks of age significantly (P less than 0.01) reduced lymphoma development. In a further experiment, surgical bursectomy of REV-infected chickens followed by intravenous inoculation of the chickens with a single cell suspension of their own bursa cells at 2, 4, 9, or 13 weeks of age resulted in lymphoid tumors in chickens treated at 9 or 13 weeks but not in chickens treated at 2 or 4 weeks of age. Furthermore, this treatment did not shorten the incubation period for lymphoma development. These findings argue very strongly that transforming target cells are primarily in the bursa of Fabricius. The data also suggest that a minimum residency of 4 weeks in the bursa is required for infected bursa cells to become transformed. Therefore, lymphomagenesis induced by REV in chickens appears similar to that induced by the avian leukosis virus group.     

Clinical effects, virological and serological responses in chickens following in-ovo inoculation of reticuloendotheliosis virus

Six-day-old embryonated specific pathogen free chicken eggs were inoculated with reticuloendotheliosis virus (REV) into the yolk sac and were incubated until they hatched. The hatchability of eggs inoculated with REV was significantly less (P less than 0.025) than that of media-inoculated controls. Although there were no significant differences in the body weights of these chickens at hatching, there were differences (P less than 0.001) at 6, 25 and 51 days of age between the infected and control chickens. Six of 10 chickens hatched from eggs inoculated with REV had feathering defects at 6 days of age. All chickens hatched from infected eggs had cell-free viraemia and antigenaemia, but not precipitating antibodies. Some of these chickens had very low neutralising antibody titres (less than 45) when examined at 25 and 37 days of age, as did all 10 chickens at 51 days of age. A low rate of horizontal transmission was indicated by the detection of antibodies at 37 and 51 days of age in chickens running in contact with the chickens hatched from eggs inoculated with REV.