The effect of light intensity on the behavior, eye and leg health, and immune function of broiler chickens.

Broilers are typically raised commercially in dim lighting. It has been suggested that providing brighter light intensity could improve health and provide opportunities for more normal behavioral rhythms. We examined the effects of 3 photophase light intensities (5, 50, and 200 lx) on activity patterns, immune function, and eye and leg condition of broilers (n = 753; 6 replicate pens/treatment). Broilers were reared with one of these intensities from 1 to 6 wk of age; photoperiod consisted of 16L:8D with 1 lx intensity during the scotophase. Broilers reared with 5 lx were less active (P = 0.023) during the day than 50 or 200 lx and showed less (P < 0.0001) change in activity between day and night than 50 or 200 lx. There was no difference between treatments for final BW (2.30 +/- 0.02 kg) or for most immune parameters (IgG primary and secondary responses to keyhole limpet hemocyanin, B and T lymphocyte proliferation, plasma lysozyme, haptoglobin, NO, whole blood killing of Escherichia coli and Staphylococcus aureus), but there was a trend (P = 0.072) for a greater IgM response in 50 lx (6.21 titer) than 5 lx (5.78 titer), with 200 lx (5.92 titer) intermediate. There was no effect of light intensity on back-to-front (1.13 +/- 0.01 cm) or side-to-side (1.48 +/- 0.01 cm) diameter of the eyes or on corneal radii (0.82 +/- 0.01 cm), but 5 lx (2.33 +/- 0.07 g) had heavier eyes (P = 0.002) than 50 lx (2.09 +/- 0.04 g) or 200 lx (2.11 +/- 0.04 g). There were no differences in gait score, although 200 lx broilers had more hock and footpad bruising (P = 0.038) but fewer erosions (P = 0.006) than 5 or 50 lx. Increased daylight intensity had little effect on broiler health but resulted in more pronounced behavioral rhythms.

Evaluation of the effectiveness of two infectious bronchitis virus vaccine programs for preventing disease caused by a California IBV field isolate.

Infectious bronchitis virus CA99 serotype was isolated from several broiler flocks in Northern California. The virus caused late-onset respiratory disease and increased airsacculitis condemnation in affected flocks despite the use of an established infectious bronchitis virus vaccination program. An experimental study compared Holland/Arkansas and Massachusetts/Arkansas vaccination protocols to determine the efficacy of commercial infectious bronchitis virus vaccines in reducing respiratory disease and airsacculitis lesions found at processing that were associated with a CA99 field isolate. All vaccination groups were given Massachusetts/Connecticut strains of infectious bronchitis virus vaccines at age 1 day followed by vaccination with either Holland/ Arkansas or Massachusetts/Arkansas vaccine strains at 18 days of age. Birds were challenged at age 31 days with a CA99 field isolate. Gross pathology, histopathology, and virus isolation were evaluated. Chickens vaccinated with Holland/Arkansas had marginally better protection against CA99 challenge than chickens vaccinated with Massachusetts/Arkansas, although differences were not statistically significant.

Predation as a cause of neurologic signs and acute mortality in a pheasant flock.

A flock of approximately 15,000 ring-necked pheasants (Phasianus colchicus) was evaluated for a sudden increase in mortality and acute neurological signs after having been previously diagnosed 3 wk earlier with a chronic respiratory disease of undetermined etiology. Approximately 25 live birds were displaying neurological signs including circling, ataxia, and obtunded behavior and 50 birds were dead. Three birds with neurological signs were submitted for evaluation. Extensive subcutaneous hemorrhage over the head and penetrating puncture wounds through the skull and into the brain were found. Trauma from a wild predatory mammal, most likely the long-tailed weasel (Mustela frenata) that had invaded the pheasant house and expressed surplus killing behavior was determined to be the cause of the acute neurological signs and mortality. The relationship of the chronic respiratory disease to the predation episode was not determined but it is possible that pheasants with severe respiratory disease may have had increased susceptibility to predation.

Isolation of a reovirus from poult enteritis and mortality syndrome and its pathogenicity in turkey poults.

Poult enteritis and mortality syndrome (PEMS) is an acute, infectious intestinal disease of turkey poults, characterized by high mortality and 100% morbidity, that decimated the turkey industry in the mid-1990s. The etiology of PEMS is not completely understood. This report describes the testing of various filtrates of fecal material from control and PEMS-affected poults by oral inoculation into poults under experimental conditions, the subsequent isolation of a reovirus, ARV-CU98, from one of the PEMS fecal filtrates, and in vivo and in vitro studies conducted to determine the pathogenicity of ARV-CU98 in turkey poults. In order to identify a filtrate fraction of fecal material containing a putative etiologic agent, poults were challenged in two independent experiments with 220- and 100-nm filtrates of fecal material from PEMS-negative and PEMS-positive poults. The 100-nm filtrate was chosen for further evaluation because poults inoculated with this filtrate exhibited mortality and significantly lower (P < or = 0.05) body weight and relative bursa weight, three clinical signs associated with PEMS. These results were confirmed in a third experiment with 100-nm fecal filtrates from a separate batch of PEMS fecal material. In Experiment 3, body weight and relative bursa and thymus weights were significantly lower (P < or = 0.05) in poults inoculated with 100-nm filtrate of PEMS fecal material as compared with poults inoculated with 100-nm filtrate of control fecal material. Subsequently, a virus was isolated from the 100-nm PEMS fecal filtrate and propagated in liver cells. This virus was identified as a reovirus on the basis of cross-reaction with antisera against avian reovirus (FDO strain) as well as by electrophoretic analysis and was designated ARV-CU98. When inoculated orally into poults reared under controlled environmental conditions in isolators, ARV-CU98 was associated with a higher incidence of thymic hemorrhaging and gaseous intestines. In addition, relative bursa and liver weights were significantly lower (P < or = 0.05) in virus-inoculated poults as compared with controls. Virus was successfully reisolated from virus-challenged poults but not from control birds. Furthermore, viral antigen was detected by immunofluorescence in liver sections from virus-challenged poults at 3 and 6 days postinfection and virus was isolated from liver at 6 days postinfection, suggesting that ARV-CU98 replicates in the liver. In addition to a decrease in liver weight, there was a functional degeneration as indicated by altered plasma alanine aminotransferase and aspartate aminotransferase activities in virus poults as compared with controls. Although this reovirus does not induce fulminating PEMS, our results demonstrated that ARV-CU98 does cause some of the clinical signs in PEMS, including intestinal alterations and significantly lower relative bursa and liver weights. ARV-CU98 may contribute directly to PEMS by affecting the intestine, bursa, and liver and may contribute indirectly by increasing susceptibility to opportunistic pathogens that facilitate development of clinical PEMS.

Protective immunity to infectious bronchitis in broilers vaccinated against Marek's disease either in ovo or at hatch and against infectious bronchitis at hatch.

Two experiments were conducted using commercial broiler chickens to determine if Marek's disease (MD) vaccines HVT/SB-1 and HVT plus CVI-988 given either in ovo or at hatch adversely affected the efficacy of infectious bronchitis (IB) vaccines (Ark and Mass serotypes) given by eyedrop on the day of hatch. Nonvaccinated negative controls and controls that received only IB vaccines were included in each study. Birds were challenged with either infectious bronchitis virus (IBV) Mass-41 or IBV Ark-99 on either day 26 or 27 of age. Protection was assessed 5 days post-IBV challenged by virus isolation from the trachea. The day of hatch mean antibody titer to IBV was 12,668 +/- 4704 and 2503 +/- 3243 by enzyme-linked immunosorbent assay in experiments 1 and 2, respectively. In each study, nonvaccinated controls had a significantly higher (P < or = 0.05) incidence (88%-100%) of IBV challenge virus isolation than did controls vaccinated for IB but not for MD. Analysis of data from both studies showed that protection to IB in groups that received only IB vaccines at hatch ranged from 55.0% to 77.3%, whereas protection to IB in groups receiving both MD and IB vaccines ranged from 50.0% to 95.5%. In both experiments and within IBV challenge serotype, broilers given MD vaccines (in ovo or at hatch) and IB vaccines at hatch had protection rates to IBV challenges that were not significantly less (P < or = 0.05) than IB protection rates of groups that received only IB vaccines at hatch. Analysis of these data shows that administration of high-titered MD vaccines either in ovo or at hatch did not affect the efficacy of an IB vaccination (serotypes Ark and Mass) given by eyedrop at hatch.

Pathogenicity of attenuated infectious bronchitis viruses for oviducts of chickens exposed in ovo.

A fixed effects, completely randomized factorial design was used to study the effect of infectious bronchitis virus (IBV) inoculation at two different exposure ages and three postinoculation (PI) durations on chick oviduct pathology. Maternal antibody-positive chicken embryos at 18 days of embryonation (ED) and newly hatched chicks were inoculated with an IBV vaccine (V-IBV) or with an IBV vaccine that had been serially passaged 21 times in chick kidney tissue culture (P-IBV). Hatchability of eggs inoculated with V-IBV at 18 ED was significantly lower (27%) than eggs that were not inoculated with IBV or were inoculated with P-IBV (45-58%, P < 0.01). Chicks from all treatment groups survived to 5 days after hatch. Pathologic changes in the oviduct were evaluated at 9, 18, and 27 days PI by light microscopy. Inoculation of V-IBV and P-IBV in the presence of maternal antibodies did not result in any oviduct pathology at 9, 18, and 27 days PI. Respiratory clinical signs, however, were observed in 61% and 5% of chicks inoculated with V-IBV at 18 ED and at hatch, respectively. Respiratory clinical signs were not observed in control birds, birds inoculated with P-IBV at 18 ED, or birds inoculated with P-IBV at hatch.

Efficacy of a novel infectious bursal disease virus immune complex vaccine in broiler chickens.

Two experiments were conducted to test the efficacy of a novel infectious bursal disease virus (IBDV) vaccine in broiler chickens with maternal IBDV immunity. The IBDV vaccine was formulated by mixing IBDV strain 2512 with bursal disease antibodies (BDA) to produce the IBDV-BDA complex vaccine. In Expt. I, 1-day-old Cobb x Cobb broiler chickens were vaccinated subcutaneously with either IBDV-BDA or commercial live intermediate IBDV vaccine (vaccine A) or were left unvaccinated. In Expt. 2, the vaccine A group was not included; instead, IBDV strain 2512 was included. Chickens were maintained in isolation houses. On day 28 (Expt. 1) and day 32 (Expt. 2) of age, chickens from each group were challenged with a standard USDA IBDV (STC strain) challenge. Challenged and unchallenged chickens were evaluated for their bursa/body weight ratios and antibody titers 3 days post-challenge. Bursae collected from Expt. 2 were examined histologically to evaluate bursal lesions and confirm gross examination. None of the unvaccinated chickens was protected against the challenge virus as evidenced by the presence of acute bursal lesions (edema/hemorrhage). All chickens receiving the IBDV-BDA complex or the IBDV strain 2512 (Expt. 2) were protected from the challenge virus as evidenced by no acute bursal lesions. Additionally, chickens receiving the IBDV-BDA complex vaccine or the IBDV strain 2512 had antibody titers to IBDV, indication the presence of an active immune response. In Expt. 1, chickens vaccinated with vaccine A and challenged had bursal lesions similar to those observed in the unvaccinated, challenged chickens. These chickens also showed no indication of active immunity against the virus. These results suggest that the 1-day-of-age-administered IBDV-BDA complex vaccine can induce active immunity and protection against a standard IBDV challenge in the face of variable levels of maternal IBDV immunity.

Lack of protection against avian cholera by vaccination with recombinant P6-like protein from Pasteurella multocida.

The gene encoding the P6-like protein of Pasteurella multocida was cloned in the baculovirus expression system. Baculovirus-expressed recombinant protein was used to parenterally immunize 6-wk-old Nicholas broad-breasted white turkeys. Turkeys developed significant antibody titers to the recombinant protein as measured by enzyme-linked immunosorbent assay. Two weeks after the last immunizing injection, vaccinated turkeys were placed in contact with turkeys infected with P. multocida strain P1059, as were nonvaccinated control birds. No differences occurred in percent mortality between the two groups. We conclude that parenterally administered recombinant P6-like protein does not protect turkeys from avian cholera.

Association between the Rfp-Y haplotype and the incidence of Marek's disease in chickens.

Certain haplotypes at the major histocompatibility (B) complex (Mhc) of the chicken provide an easily demonstrated influence on tumor formation following infections with Marek's disease virus (MDV). Recognition that there is a second histocompatibility complex of genes in the chicken, Rfp-Y, comprised of Mhc class I and class II genes, some of which are at least transcribed, evokes the question of whether this gene complex might also influence the outcome of MDV infections. To test this hypothesis, pedigree-hatched chicks in families from the original Rfp-Y-defining stock in which three Rfp-Y and two B system haplotypes are segregating were challenged with the RB1B strain of MDV. Birds with the Y3/Y3 genotype were found to have 2.3 times the risk of developing a tumor compared with birds with other Rfp-Y genotypes combined (P <0.02). Additionally, birds carrying the BR9/B11 genotype had 2.3 times the risk of tumor formation, relative to birds with the B11/B11 genotype (P <0.02). We found no evidence for an interaction between genotypes within the B and Rfp-Y systems. These data provide evidence that Rfp-Y haplotypes, as well as B haplotypes, can significantly influence the outcome of infection with MDV.

Determination of optimum formulation of a novel infectious bursal disease virus (IBDV) vaccine constructed by mixing bursal disease antibody with IBDV.

A novel vaccine against infectious bursal disease virus (IBDV) has been developed. The new vaccine was constructed by mixing bursal disease antibody (BDA) contained in whole antiserum with live IBDV before lyophilization. To establish various formulations of BDA and IBDV, several BDA doses between 5 units and 80 units of BDA/50 microliters were mixed with 100 EID50/50 microliters of IBDV suspension in Expt. 1; in Expt. 2, several IBDV doses between 10 EID50/50 microliters and 977 EID50/50 microliters of IBDV suspension were mixed with 24 units of BDA/50 microliters. Vaccine preparations were administered subcutaneously to the nape of 1-day-old specific-pathogen-free (SPF) chicks. Safety, potency, and immunogenicity of the different vaccine formulations were evaluated using bursal weight, bursal gross examination, and IBDV antibody titer. Some bursae were examined histologically to confirm gross examinations. Several vaccine formulations were safe and efficacious and met the safety, potency, and immunogenicity criteria. A vaccine construct of 100 EID50 mixed with 24 units of BDA was selected as the release dose. When administered at 1 day of age, the novel vaccine allows for delayed infection of the bursa until after days 6-8 of age in SPF chicks, while initiating potency and immunogenicity to an IBDV challenge. The addition of BDA to the IBDV results in a complex vaccine that allows for safer immunization in SPF birds than under administration of the vaccine virus without BDA.

Embryo vaccination of chickens with infectious bronchitis virus: histologic and ultrastructural lesion response and immunologic response to vaccination.

Chicken embryos 18 days of age and newly hatched chicks were vaccinated with an infectious bronchitis virus (IBV) vaccine (V-IBV) or with an IBV vaccine that had been serially passaged 40 times in chick kidney tissue culture (P-IBV). Immunologic and pathologic changes in the chicks were compared at selected intervals until the 35th day. Pathologic changes were evaluated by light, transmission, and scanning electron microscopy. Immunologic changes were assayed by a constant virus-diluting serum plaque-reduction test in chicken cell cultures, by 51Cr-release cytotoxicity assays, and by phytohemagglutination (PHA) responses. Embryos vaccinated with P-IBV and 1-day-old chicks vaccinated with V-IBV had similar transient lesions that were confined primarily to the trachea. Embryo vaccination and posthatch vaccination induced similar primary and secondary antibody responses in chicks. It was concluded that neither vaccination technique consistently influenced PHA response of whole blood cells or natural killer cell reactivity of spleen effector cells. Additionally, effector cells cytotoxic to IBV-infected target cells were not detected in chicks vaccinated as embryos or at hatch. The pathologic and immunologic effects of vaccination with P-IBV were comparable to those induced by conventional vaccination of chicks.

In ovo pathogenicity of Mycoplasma iners strain Oz.

Embryonating chicken eggs were inoculated with the type strain (PG30) of Mycoplasma iners and with an additional strain of this species designated Oz. Marked gross and histopathologic lesions were observed in the embryos inoculated with strain Oz but not in those infected with strain PG30. Gross lesions were manifested by an enlargement of one or more joints that often contained a caseous exudate, both in the joint space and periarticularly. In the order of frequency, the most common lesions were found in the following joints: tibiotarsal, distal humoral, proximal humoral, femoral, mandibular, tibiofemoral, and phalangial. Similar caseous foci were also seen in the liver and, rarely, in the heart. Histologically, the most prominent lesion found in the joints and viscera was a multifocal caseous necrosis accompanied by the formation of granulomas. Many joints had progression of the inflammatory cells outward from the joint spaces along the periosteal surfaces, and the articular cartilages contained erosions and focal necrosis.

Mycoplasma infection in a commercial goat dairy caused by Mycoplasma agalactiae and Mycoplasma mycoides subsp. mycoides (caprine biotype).

A commercial dairy goat herd of 600 animals experienced sudden onset of arthritis/polyarthritis, clinical mastitis, and sudden death in does. The offending infectious agents were Mycoplasma agalactiae and M. mycoides subsp. mycoides (caprine biotype). The disease syndrome began approximately 4 weeks following the 1) introduction into the herd of a lactating doe with no apparent clinical signs and 2) a breakdown of proper hygienic conditions in the milking parlor. Over a period of 3 weeks, 90 does (15%) either died or were culled because of arthritis/polyarthritis and mastitis. A management decision resulted in only the does affected with M. mycoides subsp. mycoides being submitted for necropsy; those affected with M. agalactiae, which were in a different "string," were not submitted for evaluation. Gross necropsy of the does affected with M. mycoides subsp. mycoides showed purulent discharges from the udders, enlarged supramammary lymph nodes, enlarged and firm spleens, and swollen livers. Microscopic findings were characterized by a loss of vascular integrity and diffuse fluid leakage in multiple organs. Antibiotic therapy with tylosin was attempted but was not successful. The outbreak was terminated following the removal or segregation of affected does and implementation of hygienic conditions in the milking parlor.

Preparation and characterization of chicken intraepithelial leukocytes.

Intraepithelial leukocytes (IELs) form an important component of the intestinal immune system. Several methods of preparing chicken IELs were compared for cell yield, cell populations, and functional activity against a natural killer (NK)-susceptible lymphoblastoid cell line (LSCC-RP9). In addition, an attempt was made to immortalize IELs by infection with reticuloendotheliosis virus (REV) for use in cell-trafficking studies. Intestinal fragments were incubated in 5 mM DL-dithiothreitol at 41 degrees C for 15 min followed by three 45 min incubations in 0.1 mM EDTA. Gentle shaking of the intestinal fragments every 5 min caused considerably less damage to the epithelial cell layer than slow stirring with a magnetic bar. The latter method yielded more cells, but these were not functionally active in the NK-cell assay. The more gentle method resulted in a lower cell yield, but these cells were able to lyse LSCC-RP9; the percentage of lymphocytes present was lower but these contained a higher proportion of large granular lymphocytes. Infection of IELs with REV did not immortalize these cells.

Feline sporotrichosis: a report of five cases with transmission to humans.

Sporotrichosis was diagnosed in five cats. Seven humans exposed to these cats subsequently developed the disease. All feline cases developed draining ulcers, and in four of five cases there was disseminated cutaneous involvement. Histologically, numerous Sporothrix organisms were noted in cutaneous lesions and overlying exudate. The seven humans who became infected were involved in cleaning and medicating cats with the disease; all human patients developed a localized lymphocutaneous form of sporotrichosis. In four of the human cases there was no history of an associated penetrating wound. The large number of Sporothrix organisms is a distinct feature of feline sporotrichosis and indicates that the cat may be the only domestic animal species that can readily transmit this disease to humans. In addition, any contact with the draining lesions of affected cats offers the potential for human infection.

Chicken embryonal vaccination with avian infectious bronchitis virus.

A commercial infectious bronchitis virus (IBV) vaccine of the Massachusetts 41 strain was injected in embryonating chicken eggs on embryonation day (ED) 18. The IBV vaccine was pathogenic for embryos, and it was passaged in chicken kidney tissue culture to reduce the pathogenicity. At the 40th tissue culture passage (P40-IBV), the virus became apathogenic for the embryos. Maternal antibody-positive or -negative chicks hatching from eggs injected with P40-IBV developed antibody to IBV and were protected against challenge exposure at 4 weeks of age with virulent Massachusetts 41 IBV. Although P40-IBV protected chicks when administered on ED 18, this virus did not protect chicks well if given at hatch. When combined with the turkey herpesvirus (HVT), P40-IBV given on ED 18 did not interfere with the protection against challenge exposure with virulent Marek's disease virus, nor did the presence of HVT interfere with protection by P40-IBV. Thus, under laboratory conditions, IBV vaccine could be combined with HVT to form a bivalent embryonal vaccine.

Comparative viral, immunologic, and pathologic responses of chickens inoculated with herpesvirus of turkeys as embryos or at hatch.

Chickens were vaccinated with the herpesvirus of turkeys (HVT) at embryonation day 17 or 18 or at hatch and various responses of the 2 vaccinated groups were compared. In embryo-vaccinated chickens, HVT titers were high in the lungs before HVT could be isolated from other tissues. Seemingly, embryos acquired infection via the respiratory tract. In hatch-vaccinated chickens, HVT was first isolated from spleen and then from other tissues. Titers of recoverable HVT in tissues of embryo-vaccinated chickens were higher than in those of hatch-vaccinated chickens, particularly during the 1st week of age. Anti-HVT antibodies and natural killer cell reactivity in spleen effector cells were comparably increased in both vaccinated groups. Embryo vaccination with HVT did not cause progressive lesions, reduction in body weight gain, or impairment of humoral and cellular immune functions. Seemingly, HVT can be used safely as an embryonal vaccine in chickens.