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.

Effects of continuous feeding of toxaphene to white leghorn layers

Graded levels of toxaphene 0, 0.5, 5.0, 50 and 100 ppm were added to the diets of female white leghorn chicks from one day of age. Each treatment consisted of 90 randomly selected birds divided into three replicates of 30 birds each. Birds fed the 5, 50, and 100 ppm level of toxaphene exhibited osteomalacia manifested by sternal deformities and extremely friable ribs. A decrease in egg shell strength was found in chickens eating feed containing 5 ppm level of toxaphene. Toxaphene did not significantly alter egg production, hatchability or fertility in this trial.

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.

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.

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.

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.

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.

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.

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.

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.

Disease prevalence in Georgia turkey flocks in 1986

Disease prevalence in turkeys was estimated by totaling the flock size of necropsy cases submitted to the University of Georgia in 1986 for each disease reported and comparing it with the population at risk. Fowl cholera was the most prevalent disease in both commercial tom flocks (18.0%) and breeder hen flocks (14.7%). Prevalence of colibacillosis was 15.9% in commercial tom flocks, and prevalence of aspergillosis was 8.5% in commercial tom and 4.9% in breeder hen flocks.

A method to rapidly convert Newcastle disease virus and infectious bronchitis virus ImmunoComb scores into conventional hemagglutination-inhibition titers

ImmunoComb scores are highly correlated to hemagglutination-inhibition (HI) titers against infectious bronchitis virus and Newcastle disease virus. Statistical calculations permit using an individual COMBSCORE to predict the corresponding HI titer value. Tables are presented to facilitate the transformation of COMBSCORES into HI titers.

Diagnostic summary of 1986 turkey, broiler breeder, and layer necropsy cases at the University of Georgia

Turkey, broiler breeder, and layer cases submitted for necropsy in 1986 to the University of Georgia were categorized by diagnosis, grouped by clinical features, season, age, and presenting history, and evaluated for statistically significant patterns. The most commonly diagnosed diseases were: fowl cholera in turkeys, 64 cases (34.4% of cases; 26.2% of diagnoses); staphylococcal arthritis/synovitis (SA/S) in broiler breeders, 35 cases (20.7%; 17.7%); and osteomalacia in layers, 17 cases (21.0%; 15.6%). In turkeys, fowl cholera, colibacillosis, and aspergillosis were significantly more common in the fourth, second, and third quarters of the year, respectively; enteritis and viral enteritis were more common in early grow-out, and osteomyelitis, SA/S, and synovitis were greatest in late grow-out. Overall, musculoskeletal problems in turkeys were more common in the third quarter and were less common in the first and fourth quarters. Erysipelas occurred most frequently in turkeys 50 to 112 days of age. In both broiler breeders and layers, SA/S was more common in the second quarter, and a history of musculoskeletal problems was less common in both post-peak-production broiler breeders and layers. Fowl pox was more common in the fourth quarter and in late-production broiler breeders. In layers, osteomalacia and Marek's disease were more common in the first and fourth quarters, respectively.

Marek's disease virus-induced transient paralysis in chickens: alterations in brain density

The presence of brain edema and its distribution in Marek's disease virus (MDV)-induced transient paralysis (TP) was determined in genetically resistant and susceptible inbred White Leghorn chickens. Density measurements on samples from the cerebellum, cerebral cortex, optic chiasm, and optic lobe were determined on continuous density Percoll gradients. At 9 days post inoculation of MDV, the cerebellums from the susceptible line of chickens were significantly less dense than cerebellums from the resistant line or the controls of either line. The cerebellar edema, as measured by tissue density, coincided with the transient neurological symptoms and was not present in brain tissue from clinically recovered TP birds.

A study of breeder vaccination programs and problems in the broiler progeny in Saskatchewan utilizing enzyme-linked immunosorbent assay

A survey of antibodies against infectious bursal disease virus (IBDV), infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and reovirus (RV) was conducted in broiler-breeder flocks and selected progeny broiler flocks utilizing the enzyme-linked immunosorbent assay. Marked differences in antibody titers between different breeder flocks were related to differences in vaccination programs. Poor performance in some progeny broiler flocks was related to low antibody titers against IBDV in the source breeder flocks. Progeny broiler flocks in which there was a high incidence of condemnations for airsacculitis had elevated antibody titers against IBV. A few progeny broiler flocks that experienced high mortality due to gangrenous dermatitis had no antibody titers against IBDV at processing. Antibody titers against RV were very variable and could not be related to any production problems.

Microscopic and ultrastructural renal pathology of oosporein-induced toxicosis in broiler chicks

Kidneys from broiler chicks receiving 300 micrograms of oosporein K salt per gram of feed continuously from 0 to 21 days of age were examined by light and electron microscopy. Chicks that died at 3 days had nephrosis of initial proximal tubular segments with an early pyogranulomatous interstitial response. Macula densa cells had cytoplasmic accumulations of periodic-acid-Schiff-positive granules. Kidneys from chicks surviving 21 days had hypercellular or atrophic glomeruli and hyperplastic dilated proximal tubules. Centrilobular distal tubules were dilated and filled with hyaline basophilic casts. Interstitial fibrosis was prominent in cortical and medullary zones. These findings indicate that oral oosporein is a severe nephrotoxin which can cause visceral urate deposition and severe nephrosis of initial proximal tubular segments. The histopathology of this mycotoxicosis was compared with those of infectious-bronchitis-induced nephrosis and avian urolithiasis syndrome.

Suppression of humoral immunity in chickens with carrageenans

Carrageenans (CGN), sulphated polygalactans, have been reported to be cytotoxic for macrophages in vitro. On this basis, the effect of the 3 major CGN types on humoral immune responses in chickens was investigated. Carrageenan had no effect on body and lymphoid organ weights. Histologically, CGN produced a significant proliferation of reticuloendothelial cells in liver and spleen, but no changes were observed in lymphocyte populations of the bursa of Fabricius, thymus, or spleen. Intracoelomic pretreatment with high doses of CGN induced a marked suppression of primary responses to sheep red blood cells (SRBC) given by the same route. However, if SRBC were injected intravenously into chickens already treated intracoelomically with CGN, no evidence of suppression was demonstrated. Antibody responses to Brucella abortus (BA), a T-independent antigen, were not affected by intracoelomic treatment with CGN. Intravenous pretreatment with CGN did not alter antibody responses to SRBC and BA given by the same route.

Comparative study of the pathogenicity of avian reoviruses

Reovirus strains CO8 and 81-5, isolated from chickens with malabsorption syndrome, and reovirus strain 176, isolated from chickens with tenosynovitis, were each individually inoculated into 1-day-old specific-pathogen-free chicks. Strain CO8 caused tenosynovitis and pericarditis following footpad inoculation, but it was of low pathogenicity when given by either oral or subcutaneous route. In contrast, strains 81-5 and 176 were highly pathogenic and caused severe mortality following subcutaneous inoculation. Lesions included hepatic necrosis, bursal atrophy, thymitis, and splenic hyperplasia; strain 81-5 also caused pericarditis and myocarditis. Although strain 176 caused higher mortality than strain 81-5, these two strains differed little in the severity and distribution of the lesions they caused. No signs or lesions of typical malabsorption syndrome were observed.

Application of the avidin-biotin-peroxidase complex (ABC) technique for detecting avian reovirus in chickens

An immunoperoxidase technique, avidin-biotin-peroxidase complex (ABC), was used for detecting avian reovirus in glutaraldehyde-formalin-fixed, paraffin-embedded tissues. A peroxidase-positive reaction, characterized by the presence of dark brown granules in the cytoplasm of affected cells, was found in the liver (Kupffer cells, macrophages, and hepatocytes) and bursa of Fabricius (epithelial cells, stromal cells, and/or macrophages). The early presence of peroxidase activity in the bursa of Fabricius supports our previous idea that the bursa of Fabricius may serve as a primary site of replication for natural reovirus infection.

The effect on newborn chicks of oral inoculation of reovirus isolated from chickens with tenosynovitis

Reovirus strain 176, isolated from chickens with tenosynovitis, was highly pathogenic following oral inoculation of 1-day-old specific-pathogen-free chicks. Disseminated lesions including hepatic necrosis, splenic lymphostromal cell hyperplasia, and bursal atrophy occurred on day 3 postinoculation (PI), followed by myocarditis on day 6 PI and by pericarditis and tenosynovitis on day 9 PI. Reovirus was isolated from the liver as early as day 1 PI, whereas significant neutralizing antibody was detected on day 13 PI. Mortality occurred from day 4 to day 7 PI, and the death of birds was associated with the severity of hepatic necrosis. The occurrence of tenosynovitis in virus-inoculated birds was subclinical.

Comparison of serological tests for antibodies against Newcastle disease virus and infectious bronchitis virus using ImmunoComb solid-phase immunoassay, a commercial enzyme-linked immunosorbent assay, and the hemagglutination-inhibition assay

COMBSCORES determined using the ImmunoComb solid-phase immunoassay were compared with hemagglutination-inhibition (HI) titers specific for Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and with mean enzyme-linked immunosorbent assay (ELISA) titers determined using Agritech Systems, Inc., ELISA. COMBSCORES for NDV and IBV increased proportionately in a stepwise manner as HI titers increased. The ImmunoComb solid-phase immunoassay was ablt to produce endpoint titers on sera with NDV-HI titers of 0 through 320 and IBV-HI titers of 0 through 1024 without reaching the maximum S-value. The ImmunoComb showed good correlation with the HI assay and the Agritech ELISA and should prove to be a useful tool for serological profiling, either alone or in conjunction with the HI test or commercial ELISA.

Clinical encephalitis following avian encephalomyelitis vaccination in broiler breeder pullets

Twelve-to-fourteen-week-old broiler breeder pullets and cockerels from two different companies were found to have encephalitis 2 weeks after vaccination with avian encephalomyelitis (AE) vaccine. Histologic examination and virus isolation indicated that affected chickens had AE. All chickens had been vaccinated with either one of two serials of AE vaccine approximately 2 weeks before the onset of clinical signs.

Feed refusal in swine fed ochratoxin-contaminated grain sorghum: evaluation of toxicity in chicks

In an episode of feed refusal in a swine herd, feed specimens were found to be contaminated with mycotoxin. Grain sorghum, the chief ingredient of the swine diet, was found to be the source of contamination and contained 5 mg of ochratoxin/kg of feed. Incorporation of the grain into poultry diets induced renal and hepatic lesions, reduced weight gains, decreased feed utilization, and altered serum uric acid, blood urea nitrogen, and serum creatinine concentrations in chicks.

Comparison of two commercial enzyme-linked immunosorbent assays and conventional methods for avian serology

Sera tested for hemagglutination-inhibition (HI) activity against Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and virus-neutralizing (VN) activity against infectious bursal disease virus (IBDV) and viral arthritis (VA) virus were collected from a wide variety of accessions into the Diagnostic Services Laboratory, Poultry Disease Research Center, University of Georgia. The sera were then segregated according to HI or VN titer to NDV, IBV, IBDV, or VA virus and stored frozen at -20 C until tested by two commercial enzyme-linked immunosorbent assays (ELISAs). There was good correlation of mean Flockchek ELISA titers or EIA Systems sample-to-positive (S/P) ratios with specific HI or VN titers. Flockchek ELISA profile group 3 and EIA Systems mean S/P ratio of 1.12 corresponded to what were considered in our lab to be minimum protective titers for each antigen against virulent challenge in our area.

Pinealoma in a broiler breeder

An incidental central nervous system tumor was found in a broiler breeder. The cellular mass was histologically similar to the normal pineal gland, but it was characterized by a decreased ratio of follicular/parafollicular cells, a relative increase in mitoses, a size three times greater than a normal pineal gland, and growth and expansion into adjacent cerebellar tissue. These characteristics warranted a diagnosis of pinealoma rather than pineal gland hyperplasia.