Morphometric and histologic changes in the pulmonary system of broilers raised at simulated high altitude.

Broilers were reared in conditions of hypobaric hypoxia (3500 m altitude) to investigate the development of pulmonary nodules in birds reared in hypobaric hypoxia and judged by clinical observation to be developing broiler pulmonary hypertension syndrome (BPHS); in unaffected birds reared in hypobaric hypoxia; and in birds reared at ambient atmospheric pressure. Gross pulmonary morphometric measurements, packed cell volume, electrocardiogram QRS amplitude and body weight also were compared among the three experimental groups. Results indicate that hypobaric hypoxia alone exercised little influence on the development of pulmonary nodules. Nodule numbers per section and nodule area per section were numerically greater in birds reared in hypobaric hypoxia, but there were no consistent significant differences in nodule numbers in birds which developed BPHS. As expected, absolute lung length, inter-rib distance and lung volume increased significantly with increasing age and size; but when these parameters were expressed as a function of body weight, they decreased with increasing age. Again, intergroup differences were inconsistent. Packed cell volume and electrocardiogram QRS amplitude were significantly increased in birds reared in hypobaric hypoxia.

Changes in pulmonary arterial and femoral arterial blood pressure upon acute exposure to hypobaric hypoxia in broiler chickens.

An experiment was conducted to investigate the pulmonary arterial and femoral arterial pressure responses to acute hypobaric hypoxia. Twenty-four, 7-wk-old Hubbard x Hubbard male chickens were lightly anesthetized and catheters were introduced into the right femoral artery and the pulmonary artery. The birds were then placed in a hypobaric chamber, and blood pressure responses were monitored during acute (15 min) exposures to simulated altitudes of 2,000 and 4,000 m. The pulmonary artery pressure increased .7 and 4% during the first and second exposures to a simulated altitude of 2,000 m, whereas the femoral artery pressure decreased 6 and 8% during exposures to this altitude. The pulmonary artery pressure increased 7% on the first exposure and 23% (P < .05) on the second exposure to a simulated altitude of 4,000 m. The femoral arterial pressure decreased (P < .05) on both exposures to this altitude (29 and 24%, respectively). The initial femoral and pulmonary artery pressures and changes in these pressures upon exposure to hypobaric hypoxia were not consistently correlated with the characteristics of the electrocardiogram, packed cell volume, body weight, or the right:total ventricular weight ratio. These results indicate that acute hypobaric hypoxia elicits a hypotensive response in the systemic arterial circulation and a hypertensive response in the pulmonary arterial circulation of broiler chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Influenza A viruses isolated from waterfowl in two wildlife management areas of Pennsylvania.

A survey was conducted at two wildlife management areas of Pennsylvania (USA) to evaluate an antigen capture enzyme-linked immunosorbent assay (AC-ELISA) for the detection of avian influenza viruses (AIV) in cloacal swabs from waterfowl and to determine the influenza A virus subtypes and the distribution of these viruses among waterfowl. We collected 330 cloacal swabs from hunter-killed waterfowl in the fall of 1990 and from cage-captured waterfowl in the summer of 1991. Thirty-one hemagglutinating agents were isolated by chicken embryo inoculation (CEI) of which 27 were influenza A viruses and four Newcastle disease viruses (NDV). The prevalence of AIV infection was 8.2%. Compared to CEI, AC-ELISA was only 15% sensitive and 61% specific. Based on the distribution of AIV by species of waterfowl, mallards (Anas platyrhynchos) and American wigeons (Anas americana) were at equal risk of AIV infection even though most of the AIV isolates came from mallards. Although significant crude effects of sampling site and season on AIV recovery could be established, juvenile age was identified as the primary risk factor of AIV recovery. Twelve AIV subtypes were identified by hemagglutination inhibition (HI) and neuraminidase inhibition (NI) tests. The most prevalent subytpes were H4N8 and H6N8. We concluded that AC-ELISA was not useful for the detection of AIV in cloacal swabs from waterfowl and that CEI, HI, and NI tests remain as the method of choice for AIV screening in waterfowl. Based on the results AIV infected preferentially the young which represent the high risk group in waterfowl populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic and electrocardiographic changes occurring in broilers reared at simulated high altitude.

An experiment was conducted to determine whether differences in the electrocardiograms (EKGs) of broilers reared at simulated high altitude from the day of hatch can be used to predict which birds are developing ascites. In three replicate experiments, conducted with 100 broilers per replicate, birds were reared at a simulated altitude of 3000 meters or at ambient atmospheric pressure. Lead I, II, and III EKGs were obtained from all birds on days 0, 14, 28, and 42. No consistent significant differences were seen on day 0 in the amplitude of the R or S wave or total amplitude of the QRS complex when broilers that developed ascites while being reared at simulated high altitude were compared with unaffected birds reared at simulated high altitude and with birds reared at ambient atmospheric pressure. On days 14 and 28, the average amplitude of the S wave and the total amplitude of the QRS complex were significantly higher in the ascites group than in the two other groups. Packed cell volumes were significantly higher in birds reared at simulated high altitude at all sampling days (days 14, 28, and 42) than in those reared at ambient atmospheric pressure, and they were significantly higher in the ascites group on day 28 than in the two other groups. Birds in the ascites group weighed significantly less than the two other groups by day 14, and this trend persisted.

Detection of viral antigen following exposure of one-day-old chickens to the Holland 52 strain of infectious bronchitis virus.

One-day-old specific-pathogen-free single comb White Leghorn chickens were inoculated by eyedrop with either 0.1 ml of phosphate buffered saline containing 10(4.3) EID50 of the Holland 52 strain of infectious bronchitis virus or normal allantoic fluid. Trachea, caecal tonsils and kidneys were removed from randomly selected birds at 0, 3, 5, 7 and 10 days post-inoculation (pi) and the presence or absence of viral antigen was detected utilizing virus isolation (VI), an indirect fluorescent antibody technique (IFA), or a streptavidin-biotin immunohistochemical (IH) technique. The presence of viral antigen as detected by the IH technique was also compared to histopathological changes in serial sections stained with haematoxylin and eosin. Detection of viral antigen occurred more frequently with VI than with IFA or IH. The IFA and IH techniques detected viral antigen with about the same frequency. Viral antigen was detected in the mucosa and submucosa of the trachea as early as 3 days pi, reached maximum levels at 5 days pi, and could still be detected in the mucosa at 10 days pi. In the kidney, viral antigen was not detectable by IFA or IH at 3 days pi, but could be visualized in distal convoluted tubules and collecting tubules at 5 days pi. At 7 days pi, antigen was detectable in the proximal convoluted tubules also. The presence of antigen in the caecal tonsils was sporadic, but it was detected in histiocytic cells and, occasionally, lymphoid cells of that organ.

Use of a hypobaric chamber as a model system for investigating ascites in broilers.

In a series of experiments, broilers were reared at simulated altitudes of 3000, 3500, and 5000 meters utilizing a hypobaric chamber. The purpose was to evaluate the chamber as a model for ascites syndrome and to further study the pathophysiology of this disease. Results show that this model can effectively reproduce the disease as it is seen in the field. Birds reared at the simulated altitude of 5000 meters had a statistically significant increase in EKG amplitude, packed cell volume, and heart-to-body-weight and lung-to-body-weight ratios when compared with controls reared at 366 meters. Additionally, there was a trend for birds dying of ascites to have larger-amplitude EKGs than survivors when reared at 5000 meters.

Order of exposure to high dietary calcium and gray strain infectious bronchitis virus alters renal function and the incidence of urolithiasis.

Experiments were designed to determine if Gray strain infectious bronchitis virus (IBV) infection increases the incidence of urolithiasis type kidney damage when the urine is already high in Ca and relatively alkaline due to a high Ca-low available P diet (i.e., layer ration). In addition, experiments were conducted to determine the effects of Gray strain IBV on pullet renal function of 6 and 14-wk-old pullets at 2, 5, and 10 days postinoculation (PI). Blood gas parameters were measured to determine the mechanism by which layer ration decreases hydrogen ion concentration [( H+]). Urine flow rate, glomerular filtration rate, electrolyte excretion (Na, K, Ca, P), free water clearance, urine osmolality, urine [H+], and renal plasma flow (para-aminohippuric clearance) were measured to assess renal function. Gray strain IBV increased urine [H+] and decreased renal plasma flow in 6-wk-old pullets, and induced a diuresis in 14-wk-old pullets between 5 and 10 days PI. The layer ration increased Ca excretion and induced a metabolic alkalosis, thus decreasing urine [H+] and causing urolith formation. Feeding layer ration followed by Gray strain IBV infection had an additive effect on the incidence of urolithiasis and gross kidney damage. Gray strain IBV infection 8 wk prior to feeding layer ration did not induce urolithiasis. The results suggest that the additive effect of Gray strain IBV on the incidence of urolithiasis is probably due to tubular damage rather than direct changes in renal function parameters.

Effect of dietary acidification and alkalinization on urolith formation and renal function in Single Comb White Leghorn laying hens.

One of the major causes of mortality in poultry is urolithiasis. Although two of the major causes of urolithiasis have been defined, active and preventative treatments for this disease have not been extensively field tested. Previous research demonstrated that a diet acidified with NH4Cl was effective in preventing the formation of uroliths in 16-wk-old pullets. In the present study, experiments were designed to evaluate the effects of dietary acidification and alkalinization on preformed uroliths in mature laying hens. Urolithiasis was induced by feeding excess dietary Ca (in commercial layer ration) during pullet growout (6 to 18 wk of age) and during the early laying period (18 to 32 wk of age). At 32 wk of age birds were randomly divided into three diet treatment groups: a normal layer ration group, an acidified layer ration group (1% NH4Cl added); and an alkalinized layer ration group (1% NaHCO3 added). Each group received the respective diets until 52 wk of age, when the experiment was terminated. Blood gas analysis at 44 wk of age demonstrated that hens fed the acidified diet had significantly higher blood H+ concentrations, lower blood bicarbonate concentrations, and lower total blood carbon dioxide levels than hens fed the alkalinized layer ration. At 52 wk of age, hens fed the acidified layer ration had higher urinary H+ concentrations, higher blood H+ concentrations, and lower blood HCO3 and total CO2 concentrations than hens fed the normal and alkalinized layer rations. The acidified layer ration group had no uroliths present in their ureters (0% urolithiasis), whereas the normal and alkalinized layer ration groups had 8.3 and 13.1% incidences of urolithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Gray strain infectious bronchitis virus and high dietary calcium on renal function of Single Comb White Leghorn pullets at 6, 10, and 18 weeks of age.

Experiments were designed to evaluate the effects of Gray strain infectious bronchitis virus (IBV) and high dietary calcium (Ca), alone and in combination, on renal function in pullets. Eight hundred female Single Comb White Leghorn chicks were raised on starter ration. Five hundred chicks were inoculated intravenously with Gray strain IBV at 4 wk of age; the remaining chicks were not exposed to IBV. At 6 wk of age, IBV-inoculated and uninoculated chicks were randomly divided into two diet treatment groups. Half the chicks were fed commercial grower ration (approximately 1.0% Ca, .6% available P) and half were fed commercial layer ration (approximately 3.25% Ca, .5% available P). Birds remained on their respective diets until 18 wk of age. Kidney function studies were conducted on anesthetized birds at 6 wk of age prior to initiation of the diet treatments, at 10 wk of age, and at 18 wk of age. The layer ration increased Ca excretion, decreased inorganic phosphate excretion, and decreased urine hydrogen ion concentration in 10-wk-old pullets in comparison with the grower ration. These diet effects on kidney function were attenuated when the pullets reached 18 wk of age. The layer ration also caused an 11.5% incidence of urolithiasis, and significantly increased kidney asymmetry in 18-wk-old pullets relative to the effects of the grower ration. Gray strain IBV exposure significantly increased kidney asymmetry in 18-wk-old pullets, but had no gross effect on kidney function clearly related to the etiology of urolithiasis. Gray strain IBV did not enhance the incidence of urolithiasis in any of the age groups.

A standardized enzyme-linked immunosorbent assay for infectious bronchitis virus: comparison with hemagglutination-inhibition and virus-neutralization assays for measuring protective antibody levels in chickens.

An enzyme-linked immunosorbent assay (ELISA) was developed to measure antibodies to infectious bronchitis virus (IBV) in chickens. The results are reported in IBV standard ELISA values calculated by comparing antibody levels in test sera with antibody levels in a series of standard reference sera. The IBV standard ELISA values were good indicators of responses to vaccination and the immune status of experimentally challenged birds. Although the assay was not serotype-specific, the sensitivity makes it ideally suited for determining the immune status of poultry flocks. The assay results compared favorably with other laboratory results, including virus-neutralization titers, hemagglutination-inhibition levels in sera, virus isolation from vaccinated/challenged birds, and the tracheal ring test results.

Some observations on the response of ring-necked pheasants to inoculation with various strains of cell-culture-propagated type II avian adenovirus.

The response of ring-necked pheasants to inoculation with three strains of cell-culture-propagated type II avian adenovirus was examined. Marble spleen disease (MSD) virus of pheasants and both avirulent and virulent strains of hemorrhagic enteritis virus (HEV) of turkeys all induced typical gross and microscopic splenic lesions of MSD; neither MSD-associated lung lesions nor mortality were noted in inoculated pheasants, regardless of strain of virus used. Pheasants inoculated with a cell-culture-propagated avirulent strain of HEV were properly immunized against challenge with virulent HEV, as indicated by seroconversion and by protection against virus-induced splenic lesions. We conclude that these strains of type II avian adenovirus are comparable in pathogenicity for pheasants and cannot be distinguished. Further, absence of MSD-associated lung lesions and mortality in pheasants maintained under controlled laboratory conditions suggest that other environmental factors are probably involved in induction of such lesions and mortality in field cases of MSD.

Chicken embryo propagation of type I avian adenoviruses.

Forty-two clone-purified, cell-culture-propagated type I avian adenoviruses (AAV) representing 11 serotypes and two intermediate strains were evaluated for virus replication (evidenced by embryo death and lesions) resulting from the inoculation of specific-pathogen-free chicken embryos via the chorioallantoic sac or yolk sac. Commonly observed embryonic changes were death, stunting and curling, hepatitis, splenomegaly, congestion and hemorrhage of body parts, and urate formation in the kidneys. Basophilic or eosinophilic intranuclear inclusion bodies characteristic of fowl adenoviruses were observed in hepatocytes. The magnitude and relative uniformity of intra- and interserotypic embryo mortality, gross lesions, and virus titers was greater in embryos inoculated via the yolk sac. This work identifies the yolk sac as a practical and sensitive chicken embryo inoculation route for poultry diagnosticians to employ. It is suggested that the yolk sac may be a reliable alternative to cell culture for the successful isolation of all type I avian adenoviruses.

The propagation of avian viruses in a continuous cell line (QT35) of Japanese quail origin.

Seven of nine avian virus families tested (Birnaviridae, Coronaviridae, Herpesviridae, Paramyxoviridae, Poxviridae, Reoviridae, and Retroviridae) were found to replicate in a quail fibroblast cell line, designated QT35, resulting in a cytopathic effect (CPE) visible with the naked eye or by low-power microscopy. In comparison, only one (Paramyxoviridae) of seven mammalian virus families tested produced an observable CPE. Cytopathic changes induced by examined viruses were round cell, syncytial, and focus formation. Trypsin did not promote cytopathic changes by selected CPE-negative avian and mammalian viruses in QT35 cells. Several avian viruses (infectious bursal disease virus, Newcastle disease virus, Canary pox virus, and reovirus) formed plaques under agar. Avian reovirus and infectious bursal disease virus produced similar titers in chicken embryo fibroblast (CEF) and QT35 cell cultures. Chicken-egg-yolk neutralizing-antibody titers to IBDV were comparable in CEF and QT35 cell-culture systems.

A case of acute pulmonary edema, splenomegaly, and ascites in guinea fowl.

Acute pulmonary edema, splenomegaly, and ascites were observed in a disease outbreak in adult white and pearl guinea fowl. The clinical history and gross and microscopic lesions resembled those described for marble spleen disease of pheasants and avian adenovirus group II splenomegaly of chickens. A small number of intranuclear inclusion bodies were found in liver, spleen, and lung sections of affected guinea fowl. Attempts to isolate virus and serological tests to detect the presence of viral antigens were unsuccessful. Adult female pearl guinea fowl experimentally exposed to pheasant and turkey isolates of type II avian adenoviruses developed gross and microscopic lesions similar to those seen in the field outbreak. The pheasant isolate was the more virulent. Intranuclear inclusion bodies were observed in liver, spleen, and lung sections of pearl guinea fowl inoculated with either of the virus isolates, and direct immunofluorescent examination revealed viral antigen in the spleen and lung.

Experimentally induced necrotic enteritis in chickens.

A 1.3 to 10% incidence of necrotic enteritis was experimentally produced in broiler-type chickens in three of five trials. The incidence range observed was considerably narrower and lower than the 5.6-37.3% range reported in the literature. Clostridium perfringens was inconsistently isolated from the liver and intestine of dosed chickens.

An infectious bronchitis virus isolated from chickens experiencing a urolithiasis outbreak. I. In vitro characterization studies.

An infectious bronchitis virus (IBV) strain isolated from commercial layers experiencing urolithiasis was 50-100 nm in size and possessed widely spaced, club-shaped surface projections. It was sensitive to lipid solvents and exhibited responses characteristic of IBV when exposed to heat, divalent cations, and trypsin. Reciprocal virus-neutralization tests demonstrated it to be closely related to Gray, JMK, Delaware 2868, and Delaware 2897 strains of IBV.

Effect of dietary acidification on kidney damage induced in immature chickens by excess calcium and infectious bronchitis virus.

Experiments were designed to evaluate the effect of dietary acidification on the development of kidney lesions induced by excess dietary calcium (Ca) and Gray strain infectious bronchitis virus (IBV). Specific pathogen-free (SPF) chicks and SPF chicks inoculated with Gray strain IBV were fed one of three diets: a commercial pullet grower ration (1% Ca); a commercial layer ration (3.25% Ca); or layer ration plus .5% ammonium chloride (acidified layer ration). Gray strain IBV significantly reduced total kidney weights in males, reduced total kidney weight as a percentage of body weight in males, increased the number of gross kidney lesions, and decreased the number of filtering nephrons when compared with uninoculated birds when both groups were fed the grower ration. The layer ration induced a 60% incidence of kidney lesions, caused a significant increase in kidney weight asymmetry ratios, and caused a 25% reduction in the number of filtering nephrons. Acidifying the layer ration significantly reduced the incidence of gross kidney lesions and reduced kidney weight asymmetry ratios, but did not prevent Ca-induced reductions in filtering nephrons.

A trivalent antigen for the detection of type I avian adenovirus precipitin.

A double immunodiffusion antigen prepared from cell-culture-propagated CELO virus was not capable of detecting precipitin directed against all of the type I avian adenovirus (fowl adenoviruses) isolates tested. However, an antigen pool containing CELO-4, B-3, and IBH-2 (Tipton) fowl adenovirus isolates detected precipitin directed against representative isolates of 10 type I serotypes. Additionally, this antigen pool markedly improved detection of adenovirus field exposure.

An outbreak of avian urolithiasis on a large commercial egg farm.

A significant outbreak of avian urolithiasis was observed on a large commercial egg farm. From the initial outbreak site (a single laying house), the incidence of urolithiasis slowly spread in the ensuing months to numerous other laying houses. Increasing mortality associated with urolithiasis commenced during late growout to early lay and then leveled off when egg production peaked. At the height of the outbreak, mortality was typically 0.5% per week; 75% of this mortality was due to urolithiasis. The clinical and pathologic features of this condition are described. Both infectious bronchitis virus (IBV) and fowl adenoviruses were isolated from organ homogenates of sampled birds. A clone of the IBV strain was found to induce nephritis in specific-pathogen-free white leghorns.

Urolithiasis in pullets and laying hens: role of dietary calcium and phosphorus.

A study was conducted to test the independent and combined effects of high dietary calcium and low available phosphorus on the incidence of urolithiasis in pullets and laying hens. One thousand Single Comb White Leghorn pullets were divided into four diet treatment groups beginning at 50 days of age. A normal calcium (1%), normal available phosphorus (.6%) diet (NCNP) was fed to control pullets. Other pullet groups were fed a high calcium (3.25%), normal available phosphorus (.6%) diet (HCNP), a normal calcium (1%), low available phosphorus (.4%) diet (NCLP), or a high calcium (3.25%), low available phosphorus (.4%) diet (HCLP). At 18 weeks of age, 368 pullets were necropsied. One percent of the HCNP group and 14% of the HCLP group developed urolithiasis. Urolithiasis was not found in pullets raised on the NCNP and NCLP diets. The remaining pullets were transferred to laying cages and were fed a commercial layer ration until they were 51 weeks old. None of the hens raised on the NCNP diet, 12% of the hens raised on the HCNP diet, 2% of the hens raised on the NCLP diet, and 14% of the hens raised on the HCLP diet had urolithiasis. Renal function studies were performed on 18-week-old pullets and 51-week-old hens. Pullets raised on the HCLP diet had significantly higher urine pH, significantly lower fractional inorganic phosphate excretion, and significantly higher fractional calcium excretion when compared with pullets raised on the other diet treatments. The profound effect of the HCLP diet on renal calcium and phosphorus excretion in pullets was not retained in the hens.(ABSTRACT TRUNCATED AT 250 WORDS)