Pathologically and serologically different avian nephritis virus isolates implicated in etiology of baby chick nephropathy.

Three virus isolates (WG-3, -4, and -5) from chicks affected by baby chick nephropathy were orally inoculated into 1-day-old specific-pathogen-free chicks of lines PDL-1 and 15I. Additional chicks were orally inoculated with avian nephritis virus (ANV) strain G-4260. Chicks inoculated with isolates WG-3, -4, and -5 died between 2 and 6 days postinoculation (PI), with mortality ranging from 0% to 53.3%. Pathological findings in the dead chicks included nephrosis in chicks inoculated with WG-3, -4, and -5, and nephritis and visceral urate deposition in chicks inoculated with G-4260. The stability of the WG-5 isolate, as well as the size of the particles and the nucleic acid type, were also similar to those of the G-4260 strain. All of the examined chicks inoculated with WG-3, -4, and -5 had interstitial nephritis at 14 days PI. Therefore, the three virus isolates were considered to be ANV. However, there was no serological relationship between the isolates and ANV (G-4260 and M-8 strains).     

Pathogenicity and antigenicity of avian nephritis isolates.

The G-4260, IR-N, M-6, and M-8 strains of avian nephritis virus (ANV) were inoculated orally into 1-day-old specific-pathogen-free chicks of the line PDL-1 for pathological and serological study. Five of 15 chicks inoculated with the G-4260 strain died with visceral urate depositions. One of 15 chicks each inoculated with the M-6 and M-8 strains died with nephrosis and visceral urate deposition, respectively. No chicks inoculated with the IR-N strain died. Mean body weights of ANV-inoculated chicks, except for the IR-N-inoculated chicks, at 14 days postinoculation (PI) were significantly lower than those of control chicks (P less than 0.01). However, interstitial nephritis was observed in all ANV-inoculated birds that were histopathologically examined at 14 days PI. In the serological study, the G-4260 and IR-N strains were classified as the same serotype, and the M-6 and M-8 strains were classified as a different serotype from the G-4260 and IR-N strains. These results indicate that there at least two serotypes of ANV and its strains differ in pathogenicity.     

Pathogenicity of serotype 1 fowl adenovirus in commercial broiler chickens.

The pathogenicity of a serotype 1 fowl adenovirus (FAV-99ZH), isolated from broiler chickens exhibiting gizzard erosion, was investigated in commercial broiler chickens. Five-, 3-, and 1-wk-old commercial broiler chickens were inoculated with FAV-99ZH by both oral and ocular routes. In the 5-wk-old chickens (trial 1), none of which had the maternal antibody to FAV-99ZH, severe gizzard erosions were observed on days 5, 7, and 10 postinoculation (PI). Among the 3-wk-old chickens (trial 2), which were separated into a control group and three treatment groups according to their maternal antibody titer levels, some chickens showed clinical signs such as depression and anorexia. Compared with the control group, all the treatment groups showed decreased weight gain. One treatment group, moreover, showed significantly decreased (P < 0.05) weight gain on day 10 PI. Severe gizzard lesions, such as erosion or ulcers, were observed from day 4 PI in all treatment groups regardless of their maternal antibody levels. The 1-wk-old chickens (trial 3) were separated into a control group and two treatment groups according to their titer levels of the inoculated virus. In spite of high maternal antibody levels, severe gizzard lesions were observed in both treatment groups, which also showed decreased weight gain. One treatment group, inoculated with the higher dose, showed significantly decreased (P < 0.05) weight gain on days 10 and 14 PI compared with the control group. Fowl adenovirus was recovered mainly from gizzard and rectal (including feces) samples from inoculated chickens but was not recovered from liver samples in any of the trials or in any of the control chickens. Although the reproduced disease was similar to that described in a previous report of experimental infection of specific-pathogen-free (SPF) white leghorn chickens with fowl adenovirus, the pathogenicity of FAV-99ZH in commercial broiler chickens was more severe than that in the SPF white leghorn chickens. The results of the present study indicate that FAV-99ZH isolated from gizzard erosion had pathogenicity and produced severe lesions in the gizzards of broiler chickens and that FAV-99ZH could infect and produce illness in broiler chickens with maternal antibodies against this virus.     

Experimental infection in specific-pathogen-free chicks with avian reovirus and avian nephritis virus isolated from broiler chicks showing runting syndrome

Avian reovirus (ARV) and avian nephritis virus (ANV) were individually isolated from runty 10-day-old broiler chicks. The ARV isolate, IR-R, the ANV isolate, IR-N, and the reference strain of ANV, G-4260, were inoculated orally into 1-day-old chicks of two specific-pathogen-free (SPF) chicken lines, 151 and PDL-1. Growth retardation without the presence of gross lesions was clearly observed at 7 and 14 days postinoculation (PI) in chicks of both lines inoculated with the IR-R strain. On the other hand, in chicks inoculated with IR-N strain, growth retardation was observed only in the chicks of line 151 at 7 and 14 days PI. Microscopically, nephritis was observed in both chicken lines at 7 and 14 days PI. When chicks that were inoculated with the IR-N strain at 1 day of age were inoculated with the IR-R strain at 3 days of age, growth retardation was observed in the chicks of line PDL-1 at 10 and 17 days PI. However, the growth retardation was less severe than in the group receiving a single inoculation of the IR-R strain.     

Experimental infection of specific-pathogen-free chickens with serotype-1 fowl adenovirus isolated from a broiler chicken with gizzard erosions

Gizzard lesions were formed in specific-pathogen-free (SPF) white leghorn chickens inoculated with fowl adenovirus (FAV). The virus, serotype 1 FAV 99ZH strain (FAV-99ZH), was originally isolated from the gizzard mucosa of commercial broiler chickens exhibiting gizzard erosion with intranuclear inclusion bodies. Five-day-old and 53-day-old SPF white leghorn chickens were inoculated with FAV-99ZH by both oral and ocular routes and then examined at necropsy on days 3, 5, 7, 10, 14, and 21 postinoculation (PI). There were no clinical signs in any of the chickens after the inoculation. Focal gizzard lesions occurred macroscopically, however, in inoculated chickens at several experimental periods. FAV was recovered from tissue samples of the proventriculus, gizzard, pancreas, and rectum by day 10 or 7 PI but was not recovered from liver samples of any of the chickens. These results indicate that FAV isolated from gizzard erosion is able to reproduce gizzard lesions as necrosis and erosion in SPF white leghorn chickens and that it may have a greater degree of tissue tropism in gizzards and other digestive organs than in the liver.     

Effects of cyclophosphamide in newly hatched chickens after inoculation with avian nephritis virus

Effects of immunosuppression were compared in newly hatched chickens given cyclophosphamide (CY) after inoculation with avian nephritis virus (ANV). All CY-treated infected chickens died within 13 days after inoculation of the virus and had heavy urate deposits throughout the body. However, non-CY-treated infected, CY-treated noninfected, and non-CY-treated noninfected control chickens survived through the observation period. In a chronologic study, the value of serum uric acid in CY-treated infected chickens was more than 3 times higher than that in non-CY-treated infected chickens, and more than 9 times higher than in noninfected chickens. Serum uric acid values were coincident with the positive degree of ANV antigen in the tubular epithelial cells in the kidneys and with the severity of renal degeneration. Serologic and immunohistologic examinations did not reveal detectable antibody and IgG- and IgM-containing cells in the spleen and kidneys of CY-treated infected chickens. However, non-CY-treated infected chickens had an increased number of IgM- and IgG-containing cells and antibody against ANV on postinoculation day 6. These findings demonstrated that CY treatment enhanced the susceptibility of chickens to ANV infection.     

Response of white leghorn chickens of various genetic lines to infection with avian leukosis virus subgroup J

In Experiment 1, chickens from various white leghorn experimental lines were inoculated with strain ADOL-Hcl of subgroup J avian leukosis virus (ALV-J) either as embryos or at 1 day of age. At various ages, chickens were tested for ALV-J induced viremia, antibody, and packed cell volume (PCV). Also, at 4 and 10 wk of age, bursal tissues were examined for avian leukosis virus (ALV)-induced preneoplastic lesions with the methyl green-pyronine (MGP) stain. In Experiment 2, chickens harboring or lacking endogenous virus 21 (EV21) were inoculated with strain ADOL-Hcl of ALV-J at hatch. All embryo-inoculated chickens in Experiment 1 tested positive for ALV-J and lacked antibody throughout the experimental period of 30 wk and were considered viremic tolerant, regardless of line of chickens. By 10 wk of age, the incidence of ALV-J viremia in chickens inoculated with virus at hatch varied from 0 (line 0 chickens) to 97% (line 1515); no influence of ALV-J infection was noted on PCV. Results from microscopic examination of MGP-stained bursal tissues indicate that ALV-J can induce typical ALV-induced transformation in bursal follicles of white leghorn chickens. Lymphoid leukosis and hemangiomas were the most common ALV-J-induced tumors noted in chickens in Experiment 1. At termination of Experiment 2 (31 wk of age), 54% of chickens harboring EV21 were viremic tolerant compared with 5% of chickens lacking EV21 after inoculation with ALV-J at hatch. The data indicate that genetic differences among lines of white leghorn chickens, including the presence or absence of EV21, can influence response of chickens to infection with ALV-J.     

Cecal coccidiosis in poultry as affected by prior exposure to aflatoxin B1.

Young New Hampshire and broiler chickens were given feed containing 2 concentrations of aflatoxin B1 (0.2 or 2.0 ppm). The larger concentration caused severe toxicosis and death in the New Hampshire chicks, but did not cause gross signs in the broiler chicks. However, temporary stunting was seen on both New Hampshire and broiler chicks during periods of aflatoxin feeding, along with persisting decreased weight gains in the broiler chicks; the latter apparently recovered during the next 21 days of feeding the starter ration. New Hampshire and broiler chicks which were given feed containing aflatoxin B1 at concentrations of 0.2 and 2.0 ppm for 28 days followed by a 21-day "recovery period" and which were not given a coccidiostat were more susceptible to severe cecal coccidiosis and had more persisting hepatic and cecal lesions than did chicks not given aflatoxin. The coccidiostat was protective against both cecal damage and losses in checks challenge exposed at 49 days of age to 100,000 infective Eimeria tenella oocysts.     

Age resistance in chickens against infectious bursal disease

The day old broiler chickens possessing IBD precipitating maternal antibody when exposed either to IBD contaminated environment or challenged intrabursally with virulent virus at weekly intervals indicated 100% susceptibility around 4–5 weeks of age. However, chickens lacking maternal antibody upon intrabursal challenge were found susceptible by 2 weeks of age.     

霉变饲料中添加复方霉菌毒素吸附剂对肉鸡人工感染发生的影响

本试验旨在研究霉变饲料和／或添加复方霉菌毒素吸附剂对肉鸡人工感染发生的影响。选取140羽1日龄健康的AA肉鸡随机分成7个组．每组4个重复。第1组为空白对照组,饲喂基础日粮;第2组饲喂霉变饲料;第3～7组以混合感染病鸡病变组织匀浆饮水制作人工感染疾病模型;第3～7组分别饲喂基础日粮、霉变饲料、霉变饲料＋复方霉菌毒素吸附剂、霉变饲料＋复方霉菌毒素吸附剂＋抗氧化剂、霉变饲料＋复方霉菌毒素吸附剂＋抗氧化剂＋中药增免剂。试验期35d。结果发现,肉鸡摄入霉变饲料与摄入正常饲料相比,提高肉鸡料重比和死淘率,显著降低肉鸡增重、胸腺指数、法氏囊指数,显著降低血清IBDV、H9N1v和NDV抗体水平（P〈0．05）。给人工感染肉鸡饲喂霉变饲料与饲喂正常饲料相比．显著提高料重比和死淘率,显著降低肉鸡增重、胸腺指数和脾脏指数,显著降低血清IFN-1、IL-2、IL-4和IL-12含量以及LTR,显著降低血清IBDV、H9N1V和NDV抗体水平（P〈0．05）。霉变饲料中添加复方霉菌毒素吸附剂能显著提高混合感染肉鸡增重,并降低料重比和死淘率（P〈0．05）,显著提高胸腺指数、法氏囊指数（P〈0．05）,显著提高血清IBDV、H9N1V和NDV抗体水平（P〈0．05）。可见,霉变饲料可导致肉鸡免疫功能抑制,加重肉鸡混合感染病情;复方霉菌毒素吸附剂能有效缓解霉变饲料对人工感染肉鸡生产性能、免疫功能和病情的不利影响,抗氧化剂和免疫功能增强剂可减轻霉变饲料的毒性作用。     

The extraintestinal stages of Eimeria tenella and E. maxima in the chicken

Donor chickens given feed medicated with one or two levels of decoquinate or given non-medicated feed were infected with oocysts of Eimeria tenella or E. maxima per os. Twelve hours after inoculation with oocysts liver, mid-intestine or ceca homogenates were fed to previously uninfected recipient chickens. The results showed that continuous medication with decoquinate was effective in preventing the transfer of sporozoites from the intestine to the liver. Oocysts were detected in the feces of all recipients of tissue from non-medicated donors, showing that some sporozoites of E. maxima and E. tenella are normally transferred to liver. Young broiler chickens were immunized by oral inoculation of E. maxima oocysts. The immune status of similar chickens inoculated with sporozoites of the same species directly into the liver or spleen were assessed. During the experimental period half of the chicks were provided with non-medicated food and the remainder were given feed supplemented with decoquinate; decoquinate was effective in arresting the development of the sporozoites. Two weeks after initial infection the birds were challenged with oocysts of E. maxima per os. Injection of sporozoites into the spleen did not protect against challenge. Birds inoculated with sporozoites into the liver were unable to develop a significant level of immunity. When the drug pressure was removed from these birds, parasitism of the intestine occurred and immunity developed.     

Differences in the induction of urate deposition of specific-pathogen-free chicks inoculated with avian nephritis virus passaged by five different methods.

The G-4260 strain of avian nephritis virus (ANV) was passaged using five different methods as follows: method 1, passage three times in chorioallantoic membrane (CAM) of 11-day-old embryonated eggs (CAM3); method 2, passage twice in CAM and further passage once in yolk sac (YS) of 6-day-old embryonated eggs (CAM2-YS1); method 3, passage 11 times in CAM (CAM11); method 4, passage 10 times in CAM and further passage twice in YS (CAM10-YS2); method 5, passage as in Method 4 and then passage three times in chicken kidney cell culture (CAM10-YS2-CK3). CAM11 and CAM10-YS2 were each inoculated orally into 25 one-day-old specific-pathogen-free (SPF) chicks. Seven chicks in the CAM11-inoculated group and six chicks in the CAM10-YS2-inoculated group died or were killed because they were moribund; all had either nephrosis or urate deposition. CAM3, CAM2-YS1, CAM10-YS2, and CAM10-YS2-CK3 were each inoculated intraperitoneally into 15 one-day-old SPF chicks. No chicks inoculated with CAM3 or CAM2-YS1 died, but wo chicks inoculated with CAM10-YS2 and three inoculated with CAM10-YS2-CK3 died with urate deposition. At 14 postinoculation, plasma urate values of the CAM10-YS2- and CAM10-YS2-CK3-inoculated chicks were significantly higher than those of CAM3- and CAM2-YS1-inoculated chicks and control chicks (P less than 0.01). However, interstitial nephritis was observed in most of the ANV-inoculated birds.     

The response of Ross 308 and Hybro broiler chickens to early and late skip-a-day feed restriction

The effects of skip-a-day feeding for 14 days during the starter or grower period or for 28 days during both periods followed by ad libitum feeding to market age on the growth performance of two strains of broiler chickens, Ross 308 and Hybro, were studied over 7 weeks. Ross was superior to Hybro in weight gain, final body weight and feed conversion but consumed more feed. Overall, feed restriction reduced feed intake, weight gain and body weight in all feed - restricted birds. Also, the 14-day feed-restricted birds gained more weight and were heavier than the 28-day restricted ones. Feed restriction neither improved feed conversion nor reduced abdominal fat but decreased mortality rate. Strain | treatment interaction significantly affected only feed intake. It is suggested that for broiler chicken production in the tropics Ross 308 could be used and feed restricted for 14 days during the starter or grower period.     

Pathogenicity of Mycoplasma synoviae in chicken embryos.

Pathogenicity of Mycoplasma synoviae (MS) was examined in specific-pathogen-free (SPF) white leghorn chicken embryos. Six isolates of MS were inoculated into 7-day embryos via the yolk sac. Isolates were evaluated for gross and microscopic lesions through 19 days' incubation and for embryo lethality through 20 days' incubation. Isolates in decreasing order of lethality, from lowest to highest 50% embryo lethal dose, were WVU 1853, K1968, K1858, FMT, 92D8034, and F10-2AS. Embryo lethality was consistent with lesion incidence and severity. Embryo lethality did not correlate with previous results regarding pathogenicity of these same six isolates in SPF broiler chickens.     

Virulence of pigeon-origin Newcastle disease virus isolates for domestic chickens.

The virulence of six pigeon-origin isolates of Newcastle disease virus (NDV) was evaluated before and after passage in white leghorn chickens. Four isolates were defined as pigeon paramyxovirus-1 (PPMV-1) and two isolates were classified as avian paramyxovirus-1 (APMV-1) with NDV monoclonal antibodies. The four PPMV-1 isolates were passaged four times in chickens, and the APMV-1 isolates were passaged only once. Infected birds were monitored clinically and euthanatized. Tissues were collected for histopathology, in situ hybridization with a NDV matrix gene digoxigenin-labeled riboprobe, and immunohistochemistry with an anti-peptide antibody to the nucleoprotein. Mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index tests performed before and after passage in chickens demonstrated increased virulence of the passaged PPMV-1 isolates and high virulence of the original isolates of APMV-1. Sequence analysis of the fusion protein cleavage site of all six isolates demonstrated a sequence typical of the virulent pathotype. Although the pathotyping results indicated a virulence increase of all passaged PPMV-1 isolates, clinical disease was limited to depression and some nervous signs in only some of the 4-wk-old specific-pathogen-free white leghorns inoculated intraconjunctivally. However, an increased frequency of clinical signs and some mortality occurred in 2 wk olds inoculated intraconjunctivally with passaged virus. Histologically, prominent lesions in heart and brain were observed in birds among all four groups inoculated with the PPMV-1 isolates. The behavior of the two pigeon-origin APMV-1 isolates when inoculated into chickens was characteristic of velogenic viscerotropic NDVs and included necro-hemorrhagic lesions in the gastrointestinal tract.     

Effects of strain and different skip-a-day feed restriction periods on the growth performance of broiler chickens

The effects of 6, 10 and 14 days of skip-a-day feed removal during the starter and grower periods on the growth performance of Ross 308 and Hubbard broiler chickens were studied in a 49-day production period. Ross 308 was superior to Hubbard in weight gain, market weight and feed utilization but consumed more feed, deposited more abdominal fat and had a higher mortality rate. Overall, feed removal improved feed efficiency, had insignificant effects on abdominal fatness and mortality rate and reduced feed intake, weight gain and market weight. On each restricted-feeding regime, the birds gained as much weight as their fully fed counterparts during the period of resumed full feeding but were unable to compensate fully for the weight loss and were lighter at the end of the trial. It is suggested that for profitable broiler production under tropical conditions, Ross 308 and skip-a-day feed removal for less than 6 days from 7 to 17 days of age be considered.     

Pathogenesis of rotavirus infection in various age groups of chickens and turkeys: clinical signs and virology

Age-related susceptibility patterns of turkeys, broilers, and specific pathogen-free (SPF) White Leghorn chickens to experimentally induced infection with turkey or chicken rotavirus isolates were compared. The following determinants were evaluated: clinical signs, onset and duration of virus production, viral titers, involvement of intestinal villi in the replication of the virus, and the development of antibodies against the virus. Older turkeys and chickens were more susceptible than were their younger counterparts, turkeys were more susceptible than were broiler and White Leghorn chickens (regardless of age), and broiler chickens were slightly more susceptible than were age-matched White Leghorn chickens. Turkeys developed diarrhea, accompanied by high viral titers within 1 day after inoculation with virus. Viral antigen was found in the epithelial cells of the intestinal villi throughout the intestinal tract and some cells of the cecal tonsils. Antibodies could be detected as early as 4 to 5 days after inoculation. These findings were more pronounced in turkeys inoculated at 112 days of age than in birds inoculated at a younger age. Age-related susceptibility patterns were similar in White Leghorn and broiler chickens. Infection was subclinical in birds less than 56 days old, whereas older birds developed soft feces. Egg production in the White Leghorn chickens decreased after being inoculated with virus at 350 days of age.     

Adenoviral gizzard erosion in commercial broiler chickens

Pathologic and immunohistochemical changes caused by group I of the fowl adenovirus (FAV) serotype-1 99ZH strain, isolated from broiler chickens exhibiting gizzard erosion, were investigated in commercial broiler chickens. One hundred twenty-two chickens were inoculated with the strain by both oral and ocular routes at 1, 3, or 5 weeks of age and euthanatized for necropsy within 4-18 days of inoculation. Focal gizzard erosions were observed in the inoculated chickens of each age group. A histologically degenerative koilin layer, necrotic mucosa, intranuclear inclusion bodies in the glandular epithelial cells, inflammatory cell infiltrations in the lamina propria, submucosa, and a muscle layer were seen in the gizzards. Immunohistochemical staining showed evidence of FAV antigens in the intranuclear inclusion bodies. These findings were recognized regardless of their maternal antibody levels for FAV serotype-1. Gizzard lesions appeared later in the lower-dose-inoculated chickens than in the higher-dose-inoculated chickens. Numerous CD3-positive cells and IgY-positive plasma cells were seen in the gizzard lesions. In 5-week-old chickens the heterophil infiltrations in the lesions were milder than in younger chickens. Intranuclear inclusion bodies also were observed in the epithelial cells of the ileum or cecal tonsils of some chickens. Thus, this study shows that FAV-99ZH causes adenoviral gizzard erosion in broiler chickens without hepatic or pancreatic lesions and that cell infiltration is more severe than in dietary gizzard erosions.     

Effect of acidified feed on susceptibility of broiler chickens to intestinal infection by Campylobacter and Salmonella

Consumption of poultry meat is associated with human Campylobacter and Salmonella infections. One way to control the presence of these bacteria in broiler flocks is to make chickens less susceptible for colonisation. Acidification of feed may be a tool to reduce the Campylobacter and Salmonella carriage in broiler chickens. In the present experiments an acidified feed with high levels of organic acid, 5.7% lactic acid and 0.7% acetic acid, was applied. In an in vitro experiment the reduction or growth of Campylobacter and Salmonella was measured after addition of 10(7)cfu of these bacteria into a conventional broiler feed, acidified feed and fermented feed, whereas the numbers of Salmonella increased in non-acidified feed. The number of Campylobacter decreased 2-3 (10)log cfu. In the acidified and fermented feed a complete reduction of Campylobacter was observed within 20 min, and a total Salmonella reduction started after 1h, and was complete after 2h. Subsequently, an in vivo experiment with 100 individually housed broiler chickens showed that chickens fed acidified feed were less susceptible to an infection with Campylobacter than were chickens fed conventional feed. The size of reduction was however limited. The susceptibility for Salmonella colonisation was not affected by acidified feed. It is concluded that the role for acidified feed in the control of Campylobacter and Salmonella is limited.