Gross Morphometry, Histomorphometry, and Immunohistochemistry Confirm Early and Persistent Jejunal Crypt Hyperplasia in Poults with Enteritis and Depressed Growth.

Phosphorylated histone 3 (PH3) and cleaved caspase 3 (CCASP3) were used to detect proliferating and apoptotic cells, respectively, in the jejunums of female sibling poults, with and without enteritis and depressed growth, from hatch to day 35. Poults that developed enteritis and depressed growth (SIB flock) were raised on a commercial farm in eastern North Carolina, whereas poults with normal growth and no enteritis (TAU flock) were raised in the Teaching Animal Unit at North Carolina State University College of Veterinary Medicine. Beginning on day 5 through day 35 and at processing, TAU poults were significantly heavier than SIB poults. Jejunal weights, relative jejunal weights, and jejunal densities were greater in SIB poults from day 10 through 35. Jejunal efficiency (body weight /jejunal length) was higher in TAU poults at day 5 and days 10 through 35. Mucosal thickness was greater in SIB poults between days 7 and 21 but greater in TAU poults at days 28 and 35. From day 7 to 35, villus-to-crypt ratios were higher for TAU poults and lower for SIB poults because hyperplastic crypts formed a greater percentage of the mucosa in SIB poults. By day 7, PH3- and CCASP3-positive cells were increased in SIB poults, showing that mucosal changes resulted from combined crypt epithelial hyperplasia and increased apoptosis of villous enterocytes. Findings in this study confirm that enteritis, in the absence of clinical signs, and depressed growth in turkey poults begins by day 7, can be identified microscopically, persists for at least 35 days, is associated with lower processing weights, and has a profound negative effect on turkey growth.

Chemoprevention of spontaneous ovarian cancer in the domestic hen.

The hen is an attractive animal model for in vivo testing of agents that thwart ovarian carcinogenesis because ovarian cancer in the domestic hen features clinical and molecular alterations that are similar to ovarian cancer in humans, including a high incidence of p53 mutations. The objective of the study was to test the potential ovarian cancer chemopreventive effect of the p53 stabilizing compound CP-31398 on hens that spontaneously present the ovarian cancer phenotype. Beginning at 79 wk of age, 576 egg-laying hens (Gallus domesticus) were randomized to diets containing different amounts of CP-31398 for 94 wk, 5 d, comprising a control group (C) (n = 144), which was fed a diet containing 0 ppm (mg/kg) of CP-31398; a low-dose treatment (LDT) group (n = 144), which was fed a diet containing 100 ppm of CP-31398; a moderate-dose treatment (MDT) group (n = 144) which was fed a diet containing 200 ppm of CP-31398; and a high-dose treatment (HDT) group (n = 144), which was fed a diet containing 300 ppm of CP-31398. Hens were killed at 174 wk of age to determine the incidence of ovarian and oviductal adenocarcinomas. Whereas the incidence of localized and metastatic ovarian cancers in the MDT and HDT groups was significantly lower (up to 77%) compared to levels in the C and LDT groups (P < 0.05), the incidence of oviductal cancer was unaffected by CP-31398. CP-31398 appears to be an effective tool for chemoprevention against ovarian malignancies, but does not appear to affect oviductal malignancies.

Parvovirus-associated cerebellar hypoplasia and hydrocephalus in day old broiler chickens.

Cerebellar hypoplasia and hydrocephalus were identified in day old broiler chickens showing nervous signs, impaired mobility, and diarrhea. At postmortem examination, brains of chickens were misshapen and cerebellums were smaller than normal. Microscopically, cerebellar folia were reduced in size and irregularly shaped, and the ventricles were widely distended. Affected cerebellums had focal areas along the base of folia where the internal granular cell layer had been lost, and Purkinje cells were disorganized and located within the molecular layer. Parvovirus DNA was detected by polymerase chain reaction in three of nine brains with oligonucleotide primers designed for amplification of chicken and turkey parvoviruses. On the basis of phylogenetic analyses, the detected virus was most closely related to chicken parvoviruses. These findings suggest that a chicken parvovirus might cause a neurologic disease of young chickens characterized by cerebellar hypoplasia and hydrocephalus; however, its role as the cause of the disease remains to be confirmed.

Comparative pathology of chickens experimentally inoculated with avian influenza viruses of low and high pathogenicity.

Pathologic changes and distribution of viral antigen as determined by immunohistochemistry were compared among 4-wk-old specific-pathogen-free chickens inoculated intratracheally with avian influenza virus (AIV) isolates of either low or high pathogenicity. Viruses of low pathogenicity, previously characterized as mildly pathogenic (MP), included A/chicken/Pennsylvania/21525/83 (H5N2) (MP-Penn) and A/chicken/Alabama/7395/75 (H4N8) (MP-Alab). Viruses of high pathogenicity included A/chicken/Pennsylvania/1370/83 (H5N2), A/chicken/Victoria/A185/85 (H7N7), and A/turkey/Ontario/7732/66 (H5N9). Extremely variable clinical signs ranging from mild respiratory distress to high mortality were present among chickens inoculated with these viruses. Chickens inoculated with highly pathogenic (HP) virus had histologic lesions of necrosis and inflammation in cloacal bursa, thymus, spleen, heart, pancreas, kidney, brain, trachea, lung, and skeletal muscle, whereas chickens inoculated with MP virus had histologic lesions most frequently in lung and trachea or lacked histologic lesions. Immunospecific staining for avian influenza viral proteins was most common in cells within heart, lung, kidney, brain, and pancreas of chicken inoculated with HP viruses, but immunospecific staining was present only and infrequently in trachea and lung of chickens inoculated with MP-Penn AIV. MP-Alab did not produce lesions nor have viral antigen in inoculated chickens but did produce serologic evidence of infection. The pattern of organ involvement and viral antigen distribution in chickens intratracheally inoculated with HP AIV isolates indicates a common capability to spread beyond the respiratory tract and confirms the pantrophic replicative, pathobiologic, and lethal nature of the viruses. However, variability in severity and lesion distribution exists between different HP AIVs. By contrast, MP viruses had the ability to replicate in respiratory or enteric tracts or both and produce lesions within the respiratory tract. These MP viruses exhibited a restricted ability to replicate or produce lesions or both in nonrespiratory or nonenteric tissues; such effects were associated with only sporadic deaths.

Diazinon toxicity in broilers.

Ten 3-day-old chicks were submitted from a flock experiencing high mortality. Necropsy revealed lacrimation, diarrhea, pleural effusion, hemorrhage and ulceration of the proventriculus, and swollen, hemorrhagic livers. Numerous yellow granules were present in the crop. Assayed crop contents contained 39 ppm diazinon [O,O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidyl)phosphorothioate]. The insecticide had been applied to the litter to control fire ants. The high mortality abated after new litter was added on top of the old litter. Diazinon toxicosis was traced to ingestion of diazinon-impregnated granules and was reproduced experimentally.

Relationship of complement resistance and selected virulence factors in pathogenic avian Escherichia coli.

Complement resistance, antibiotic resistance profiles, and virulence profiles of 80 Escherichia coli isolates from the intestines of normal chickens (40 isolates) and chickens diagnosed as having colisepticemia (40 isolates) were compared. Differences were observed between the two groups for antibiotic resistance, siderophore production, presence of type 1 pili, complement resistance, motility, and size of plasmids. The systemic isolates were more likely to have siderophores and type 1 pili, and to be complement-resistant and motile than were the intestinal isolates. No differences between the two groups were observed for colicin production. Further comparison of the 10 most complement-resistant isolates from the systemic group and 10 most complement-sensitive isolates from the intestinal group revealed a correlation between an isolate's resistance to complement and its ability to kill embryos, express type 1 pili, and be motile. Virulence of avian E. coli strains appears to be correlated with complement resistance and the interaction of this resistance with the ability to produce type 1 pili and be motile.

Characteristics of Salmonella spp. and Escherichia coli isolated from broiler flocks classified as "good" or "poor" producers.

Cecal samples from 100 broiler flocks were cultured for Escherichia coli and Salmonella. Samples were selected from flocks classified as either "good" or "poor" producers by a production formula. In an attempt to identify predictors of flock productivity, isolates were studied for differences in antibiotic resistances, hemagglutination of erythrocytes, production of colicins, production of siderophores, type of hemolysis, resistance to host complement, and presence of plasmids. S. typhimurium (copenhagen) was isolated from one poor producing flock and three good producers. Salmonella isolates showed no significant differences in the parameters studied. The E. coli isolates showed significant differences only for the presence of plasmids. These data indicate that differences in host intestinal E. coli from good and poor producing flocks do not predict flock productivity.

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.

Effects of dietary aflatoxin in aflatoxin-resistant and control lines of chickens.

The resistance to a single oral dose (12 mg of aflatoxin per kg of BW) and 4 wk of dietary aflatoxin (2.5 mg per kg of feed) were investigated in chicks selected for five generations for resistance to acute aflatoxicosis (AR) and unselected control (C) chicks. The AR chicks were more resistant to a single oral dose of aflatoxin and had significantly decreased sodium pentobarbital sleeping time compared to C chicks. Four-weeks exposure to dietary aflatoxin did not result in any significant change in BW or feed conversion ratios of chicks from either the C or AR line. However, more sensitive indicators of aflatoxicosis including plasma total protein, albumin, cholesterol concentrations, and gamma glutamyl transferase activity were significantly altered in C chicks but not in AR chicks fed aflatoxin. Percentages of liver lipid and liver hyperplasia score were also significantly altered as a result of dietary aflatoxin treatment in C but not AR chicks. These data indicate that selection-associated differences exist between the C and AR lines of chickens that convey resistance to not only a single oral dose of aflatoxin but also to a more chronic dietary exposure to aflatoxin.

Effect of cold acclimation on the broiler chicks' resistance to dietary aflatoxin.

The effect of acclimation to environmental temperatures of 10 to 12 or 28 to 30 C on the resistance of broiler chicks to dietary aflatoxin was examined. Broiler chicks were acclimated from day-of-age for 2 wk to environmental temperatures of 10 to 12 or 28 to 30 C. On Day 14, a single oral dose of aflatoxin (8 mg per kg of body weight) was administered to 50 chicks in each environment. An increase in aflatoxin resistance, as assessed by survival rate, was conveyed by acclimation to cold temperatures. In each environmental chamber, a separate group of chicks was maintained for 2 additional wk, but those groups received 5 mg of aflatoxin per kg feed. By the end of the study, aflatoxicosis was characterized by: 1) a significant (P less than or equal to .05) decrease in body weight; 2) increases in spleen weight, liver weight, liver lipid, and liver dry-matter content; 3) changes in the serum levels of total protein, albumin, glucose, cholesterol, uric acid, potassium, phosphorus, iron and calcium; and 4) increased hepatic hyperplasia. Acclimation to 10 to 12 C was characterized by: 1) an increase in body weight, liver weight, spleen weight and bursa weight; 2) changes in the serum glucose and potassium levels; and 3) a decrease in glutamic-oxaloacetic transaminase activity. Significant aflatoxin by temperature interactions were evident only in serum levels of glucose and phosphorus, and in the serum activity of glutamic-oxaloacetic transaminase. These data suggest that acclimation to cool temperatures does not play a significant role in the resistance by broiler chickens to chronic aflatoxin exposure.

Marek's disease virus-induced transient paralysis in chickens: demonstration of vasogenic brain oedema by an immunohistochemical method.

The presence of vasogenic brain oedema and its distribution in Marek's disease virus (MDV)-induced transient paralysis (TP) were determined in genetically resistant and susceptible inbred White Leghorn chickens. MDV-inoculated TP-susceptible chickens with nervous signs (9 days post-inoculation) had severe vacuolation of cerebellar white matter and associated diffuse leakage of albumin and IgG. The serum protein leakage was associated morphologically with a vasculitis and intramural pseudocyst formation in the walls of blood vessels cuffed by mononuclear cells. This transient vasculitis and resulting vasogenic oedema coincided with the temporary neurological signs seen in TP-susceptible chickens. The vasculitis and vasogenic oedema were not present in brain tissue from recovered MDV-inoculated TP-susceptible chickens, MDV-inoculated TP-resistant chickens, or uninoculated control chickens from either line.

Immunosuppressive potential and pathogenicity of a recent isolate of infectious bursal disease virus in commercial broiler chickens.

At 15 days of age and in the presence of measurable levels of maternal antibody against infectious bursal disease virus serotype I (1:170 virus-neutralization geometric mean titer), a recent isolate (U-28) and a prototype virulent isolate (Edgar) of the same virus caused subclinical infections in commercial broiler chickens. Isolate U-28 caused a significant reduction in the size of the bursa of Fabricius, whereas the Edgar isolate produced splenomegaly. Both isolates reduced the serological response to Newcastle disease virus. The experimental immunosuppressive potential and pathogenicity of isolate U-28 in broiler chickens confirms the role of this virus in recent infectious bursal disease outbreaks.

Pathogenicity of recent isolates of infectious bursal disease virus in specific-pathogen-free chickens: protection conferred by an intermediate vaccine strain.

The pathogenicity of recent isolates of infectious bursal disease virus and the protection conferred against them by a commercial vaccine strain of intermediate virulence were examined in specific-pathogen-free chickens. Based on clinical signs, mortality, and macroscopic lesions in susceptible chickens, the isolates designated as A-Delmarva and U-28 were distinct from a previously known serotype I virulent isolate (Edgar). Histopathological analysis of the bursa of Fabricius did not establish differences between the field isolates. Although the vaccine strain produced some degree of bursal damage in antibody-free chickens, it was significantly less severe than the damage caused by the field isolates. The active immune response induced by vaccination was cross-protective against the pathological effects produced by the different isolates used in this study.

Marek's disease virus-induced transient paralysis in chickens. 1. Time course association between clinical signs and histological brain lesions.

Association between Marek's disease virus (MDV)-induced clinical signs of transient paralysis (TP) and brain. histological lesions (vasogenic oedema and perivascular mononuclear cell cuffs) were evaluated in TP-susceptible line G-B2 chickens in a time sequence study. The most consistent histological lesions were seen in the cerebellum. Leakage of albumin and vacuolation were parallel in development with clinical signs, but preceded the clinical signs by 6 to 12 h. During resolution of signs, a parallel decline in vacuolation, but not in extra-vascular albumin content was observed. The extravascular albumin shifted from an extracellular to intracellular location. No association was seen between the IgG leakage and vasogenic oedema or clinical signs. Perivascular mononuclear cell cuffing was statistically associated with clinical signs, but evaluation of plotted data indicated the slope for the cuffs was less than the slope for corresponding clinical signs. In addition, cuffing began 2 days prior to clinical signs. Thus, perivascular mononuclear cell cuffing was not causally associated with the TP syndrome.

Marek's disease virus-induced transient paralysis in chickens. 2. Ultrastructure of central nervous system.

Ultrastructural changes of the central nervous system (CNS) were compared in inbred White Leghorn chickens that are genetically resistant or susceptible to Marek's disease virus (MDV)-induced transient paralysis (TP). Widened extracellular spaces, containing granular material resembling protein were found in brains of TP-affected chickens. Demyelination was absent in all chickens and intramyelinic oedema was rare, present only in TP-affected chickens. Both MDV-inoculated TP-resistant and TP-susceptible chickens had CNS perivascular mononuclear cell cuffs at all sampling periods, but the TP-affected chickens also had endothelial cell hypertrophy, a greater quantity of intramural phagocytized chromatin debris, and intramural heterophils. Such findings suggest vasculitis as the causative lesion. No open endothelial cell tight junctions, endothelial cells discontinuities, or transendothelial channels were morphologically evident to explain the vasogenic oedema, but an apparent suggestive increase in coated micropinocytotic vesicles in CNS endothelial cells is a possible mechanism to explain the altered blood-brain-barrier.

Marek's disease virus-induced transient paralysis in chickens. 3. Differentiation of field cases from classical Marek's disease by central nervous system lesions.

Vasculitis with intramural pseudocyst formation primarily in the cerebellar white matter, but also in nuclei of the medulla, resulted in leakage of IgG and albumin and vacuolation of the neuropil (vasogenic oedema) in brains from chickens with clinical signs of Marek's disease virus (MDV)-induced transient paralysis (TP). Demyelination was absent. Chickens that had recovered from TP had a restored blood-brain-barrier, indicated by the rarity of vasculitis and vascular intramural pseudocysts in the cerebellum. In addition, the vacuolation and protein leakage were greatly decreased. The minor vacuolation resulted primarily from intramyelinic (cytotoxic) oedema. The small quantity of extravascular protein was being removed by microglial cells and astrocytes. In one chicken which failed to fully recover from TP (TP-prolonged) there was neither vasogenic oedema, cytotoxic oedema, nor vasculitis in the cerebellum. The medulla of the TP-prolonged chicken had a severe lymphocytosis, swollen axons, neuronal degeneration, secondary demyelination and some associated serum protein leakage. All TP-affected and TP-recovered chickens, and the TP-prolonged chicken, had perivascular mononuclear cell cuffs within all brain sections. Chickens with classical Marek's disease (MD) generally lacked CNS vacuolation, perivascular mononuclear cell cuffs, vasculitis and serum protein leakage. However, in a few cases of MD with severe perivascular mononuclear cell cuffs, focal demyelinating plaques were seen. These plaques had associated vacuolation, serum protein leakage, axonal spheroids and neuronal degeneration.

Characteristics of fowl cholera outbreaks in turkeys in Georgia in 1986.

Information was gathered from 64 cases of fowl cholera (FC) in turkey flocks through diagnostic case records, flock records, and telephone and mail surveys. Forty-five cases came from flocks of commercial turkeys, of which 15 were presented twice, and four came from mature breeder flocks. The prevalence of FC was 18.0% of commercial flocks and 14.7% of breeder flocks at risk. The average age at first diagnosis of FC was 90 days in commercial turkey flocks and 32 weeks 5 days in breeder flocks. Acute mortality was the most common presenting complaint, with a 0.37% average mortality in commercial flocks on the day of first presentation, 0.80% in commercial flocks presented a second time, and 0.43% in breeder flocks. Pasteurella multocida was cultured from 69.8% of the 361 tissue samples submitted from these cases. Novobiocin, penicillin, and chlortetracycline (CTC) had the greatest in vitro activity against isolates. Serotype 3-cross-4 was found in all 18 commercial flocks from which isolates were typed. All breeder flocks and 88.6% of commercial flocks were vaccinated before disease onset. Flocks were treated for an average of 14.3 days, most commonly with high levels of sulfadimethoxine and/or CTC. Body weights of affected birds were comparable to those of birds in unaffected flocks, but mortality and feed efficiency were worse.

Isolation, identification, and pathogenicity of two field strains of infectious bursal disease virus.

Using a sentinel bird approach, two field isolates of infectious bursal disease virus (IBDV) were isolated from broiler farms in two major broiler-producing areas of the state of Georgia. These farms had a history of subclinical IBD associated with respiratory problems and poor performance. Isolates designated as U-28 and 3212 were isolated using specific-pathogen-free chicken embryos and chicken embryo bursal cells. These isolates were identified by means of agar gel precipitation and virus-neutralization tests, direct immunofluorescence, histopathology, and electron microscopy. Isolates U-28 and 3212 appear to differ in antigenicity and pathogenicity from previously known serotype I IBDV isolates. In evaluating the extent of bursal damage caused by these field isolates, an association was found between the bursa of Fabricius/body weight index, histopathology scoring of atrophy, and morphometric analysis of the total follicle area.

Estimate of economic impact of fowl cholera in turkeys in Georgia in 1986.

Information gathered from cases of fowl cholera (FC) in commercial turkey flocks through case records, flock records, and telephone and mail surveys was used to estimate disease costs. The cost to the Georgia commercial turkey industry in 1986 from preventive measures, treatment of outbreaks, and production losses from the disease was estimated at $634,545. The cost of FC per kg of live production was estimated to be $0.015.