R. M. Fulton

Hen welfare in different housing systems

Egg production systems have become subject to heightened levels of scrutiny. Multiple factors such as disease, skeletal and foot health, pest and parasite load, behavior, stress, affective states, nutrition, and genetics influence the level of welfare hens experience. Although the need to evaluate the influence of these factors on welfare is recognized, research is still in the early stages. We compared conventional cages, furnished cages, noncage systems, and outdoor systems. Specific attributes of each system are shown to affect welfare, and systems that have similar attributes are affected similarly. For instance, environments in which hens are exposed to litter and soil, such as noncage and outdoor systems, provide a greater opportunity for disease and parasites. The more complex the environment, the more difficult it is to clean, and the larger the group size, the more easily disease and parasites are able to spread. Environments such as conventional cages, which limit movement, can lead to osteoporosis, but environments that have increased complexity, such as noncage systems, expose hens to an increased incidence of bone fractures. More space allows for hens to perform a greater repertoire of behaviors, although some deleterious behaviors such as cannibalism and piling, which results in smothering, can occur in large groups. Less is understood about the stress that each system imposes on the hen, but it appears that each system has its unique challenges. Selective breeding for desired traits such as improved bone strength and decreased feather pecking and cannibalism may help to improve welfare. It appears that no single housing system is ideal from a hen welfare perspective. Although environmental complexity increases behavioral opportunities, it also introduces difficulties in terms of disease and pest control. In addition, environmental complexity can create opportunities for the hens to express behaviors that may be detrimental to their welfare. As a result, any attempt to evaluate the sustainability of a switch to an alternative housing system requires careful consideration of the merits and shortcomings of each housing system.

Clinical and Pathologic Features of West Nile Virus Infection in Native North American Owls (Family Strigidae)

Abstract Since the initial report of West Nile virus in the northeastern United States in 1999, the virus has spread rapidly westward and southward across the country. In the summer of 2002, several midwestern states reported increased cases of neurologic disease and mortality associated with West Nile virus infection in various native North American owl species. This report summarizes the clinical and pathologic findings for 13 captive and free-ranging owls. Affected species were all in the family Strigidae and included seven snowy owls (Nyctea scandiaca), four great-horned owls (Bubo virginianus), a barred owl (Strix varia), and a short-eared owl (Asio flammeus). Neurologic signs identified included head tilt, uncoordinated flight, paralysis, tremors, and seizures. Owls that died were screened for flaviviral proteins by immunohistochemical staining of formalin-fixed tissues, followed by specific polymerase chain reaction assay to confirm West Nile virus with fresh tissues when available. Microscopic lesions were widespread, involving brain, heart, liver, kidney, and spleen, and were typically nonsuppurative with infiltration by predominantly lymphocytes and plasma cells. Lesions in owls were much more severe than those previously reported in corvids such as crows, which are considered highly susceptible to infection and are routinely used as sentinel species for monitoring for the presence and spread of West Nile virus. This report is the first detailed description of the pathology of West Nile virus infection in Strigiformes and indicates that this bird family is susceptible to natural infection with West Nile virus.

Cellular response of the respiratory tract of chickens to infection with Massachusetts 41 and Australian T infectious bronchitis viruses

Cellular response of chickens to infection with infectious bronchitis virus (IBV) was investigated by lavage of the respiratory tract of five 2-week-old specific-pathogen-free (SPF) chickens at 2, 8, 24, 48, 72, and 96 hours postinfection (PI) with either Massachusetts 41 (IBV-M41) or Australian T (IBV-T) IBV. Tissue response was monitored by microscopic examination of trachea and lung from five non-lavaged infected chickens collected at the same intervals. The total number of cells recovered by lavage from IBV-M41-infected chickens was dramatically higher than the total number recovered from IBV-T-infected chickens and uninfected controls. By contrast, the total number of cells recovered from IBV-T-infected chickens was no higher than that of the uninfected chickens. Heterophils constituted the majority of inflammatory cells recovered from both IBV-M41-infected and IBV-T-infected chickens. Heterophil numbers in IBV-M41-infected chickens paralleled total cell-number recovery, whereas heterophil numbers in IBV-T-infected birds were no higher than those in uninfected chickens. The number of lymphocytes recovered from IBV-M41-infected chickens increased 72 hours PI and continued to increase for the duration of the study. Lymphocyte numbers in IBV-T-infected chickens exceeded those in uninfected chickens only at 96 hours PI. The number of lavage macrophages in IBV-M41-infected chickens increased earlier than the number of lymphocytes but later reached a plateau. IBV-T macrophage numbers did not exceed those of uninfected chickens. Tissue damage occurred most consistently in the trachea and occurred when lavage heterophil numbers were rising or at their peak. Lavage cell recovery and composition reflected tracheal mucosa inflammatory cell infiltrate.

Light microscopic and ultrastructural characterization of cells recovered by respiratory-tract lavage of 2- and 6-week-old chickens.

This study characterized the cell population recovered by respiratory-tract lavage of 57 two-week-old and 59 six-week-old specific-pathogen-free chickens as a prerequisite to study the response of the avian respiratory tract to infectious agents. The respiratory tract of each bird was lavaged through the trachea with a series of three lavages of 10 ml of room-temperature, neutral phosphate-buffered saline per lavage. The three lavages per bird were pooled for analysis. Total recovery volumes were measured, lavage fluid cellularity was determined, and a 200-cell differential count of non-erythrocyte cells was performed. Lavage fluid recovery was greater from 2-week-old birds (91.3 percent) than from 6-week-old birds (86.3 percent). Total cells recovered were greater for 6-week-old chickens (6.79 x 10(5)) than for 2-week-old chickens (5.03 x 10(5)). Cells of epithelial origin included squamous cells, goblet cells, and both ciliated and non-ciliated columnar epithelial cells. Cells of non-epithelial origin consisted of heterophils, lymphocytes, macrophages, eosinophils, basophils, and erythrocytes. Cells of epithelial origin were the predominant cell type recovered from the 2-week-old chickens, followed by heterophils. In 6-week-old chickens, heterophils were the predominant cell type recovered, followed by cells of epithelial origin. In descending order of prevalence, the remainder of cell types recovered from chickens of both ages were lymphocytes, macrophages, eosinophils, and basophils.

Effect of route of vaccination on the prevention of infectious laryngotracheitis in commercial egg-laying chickens.

Commercial egg-laying chickens were vaccinated for infectious laryngotracheitis (ILT) with one of five commercially available vaccines (designated A, B, C, D, and E) on five separate farms by either eyedrop (e), spray (s), or double dose in the water (w) method. Groups were identified by the vaccine designation and the method of vaccination. Birds from the test groups were transferred to an isolation facility and challenged intratracheally 3 wk after vaccination. The remaining birds were given a second vaccination with the original chicken embryo origin vaccine by spray or a chicken embryo origin vaccine if the first vaccine was of tissue culture origin. After challenge, birds were monitored for clinical signs. Those surviving were euthanatized on day 6 postchallenge, and tissues and blood were collected for histopathology, virus isolation, and serology. On the basis of histopathology and enzyme-linked immunosorbent assay (ELISA) results, after one vaccination, all chickens given vaccines by eyedrop were provided better protection than nonvaccinated controls (CTLs). Birds in groups Bs and Ds had lower microscopic lesion scores whereas only birds given Bs had higher ELISA titers than CTLs. Birds in groups As and Cs and groups Bw birds taken from the rear of the barn (r) had microscopic lesion scores that were no different from those of CTLs. These same birds in addition to vaccine Ds had ELISA titers no different from those of CTLs. Of all vaccines, only A given by eyedrop or spray produced higher virus isolation titers than those of CTLs. The remainder of the vaccines produced virus isolation titers that were no different from those of CTLs. After two vaccinations, all groups had lower microscopic lesion scores than CTLs. Only Bw birds from the middle of the barn Bs, EeDs, and AsAs had virus isolation results that were higher than those of CTLs. Only groups BwrBs, CsCs, and DsDs had ELISA titers no different from those of controls. These results suggest that a priming vaccination followed by a booster dose offers better protection against ILT than a single vaccination alone. Vaccine application by eyedrop provides more uniform protection if only one vaccination is given, whereas spray vaccination may serve as an alternative method of vaccination for birds receiving two doses of vaccine.

Molecular Characterization of Mycoplasma gallisepticum Isolates from Turkeys

Abstract Two groups of Mycoplasma gallisepticum (MG) isolates (n  =  24) from Jordan were analyzed by molecular methods and compared with other Middle Eastern isolates, related international isolates, and reference strains. The first group (n  =  19) was isolated from July 2004 to January 2005 (isolation period A), and the newer group (n  =  5) from June 2007 to April 2008 (isolation period B). The groups of isolates are from chicken flocks from northern Jordan, but are not from the same farms. None of the flocks were vaccinated for MG. Random amplified polymorphic DNA analysis, targeted sequencing of the partial MG cytadhesin 2 (mgc2), and the MG 16S–23S rRNA intergenic spacer region (IGSR) divided the Jordanian isolates into two groups. All of the 19 isolates from time period A, in addition to two isolates from time period B, were indistinguishable from the F strain. Three of five isolates from time period B were characterized as wild types and were indistinguishable from each other. The wild-type field strain was readily distinguished from the F strain. It was 91% and 96.4% similar to the F strain based on Clustal-W alignments of sequences of mgc2 and IGSR, respectively. Sequence similarity of mgc2 gene of the Jordan wild-type strain to isolates from Israel and Egypt ranged from 96.5% to 100%, whereas for IGSR it was 99.4%–100%. We theorize that the F-strain live MG vaccine, commonly used in Jordan prior to 2007, was transmitted to nonvaccinated poultry in the region and was a predominant genotype during time period A.

Ocular and Encephalic Toxoplasmosis in Canaries

In this report we describe the lesions produced by the protozoal organism, Toxoplasma gondii, in the eyes and brain of the common yellow canary (Serinus canaria). Nine of 15 birds in a flock were affected with blindness, which developed over a 3-mo span, and two birds developed torticollis. Microscopic alterations within the eye consisted of a nonsuppurative chorioretinitis with large numbers of macrophages that contained the tachyzoite form of T. gondii in the subretinal space, and aggregates of tachyzoites were found in the nerve fiber layer of the retina with and without necrosis. Tissue cysts with bradyzoites were scattered throughout the meninges and neuropil of the cerebrum and cerebellum. Both forms were confirmed by transmission electron microscopy in the eye and brain. Frozen brain samples reacted with T. gondii-specific cat sera in indirect fluorescent antibody tests. The source of infection was hypothesized to be from a stray cat the owner kept that had access to some of the bird feed. Treatment (trimethoprim 0.08 g/ml H2O and sulfadiazine 0.04 g/ml in water for 2 wk) was instituted by the referring veterinarian on the remaining birds. A second treatment regime was given for 3 wk. The owner of the canaries did not return for further treatment.

The utilization of the Welfare Quality® assessment for determining laying hen condition across three housing systems

The Welfare Quality(®) Assessment protocol for poultry ( WQA: ) provides animal-based measures allowing welfare comparisons across farms and housing systems. It was used to compare Lohmann LSL Classic White hens housed in an enriched colony ( EC: ), aviary ( AV: ), and conventional cage system ( CC: ) on a commercial farm over 2 flock cycles. Hens (n = 100/system) were scored on a variety of measures. A baseline measurement was made at placement at 19 wk of age for 1 flock, since AV hens had been reared in an aviary pullet facility ( AVP: while EC and CC hens were reared in a conventional pullet facility ( CCP: ). Hens in all systems were then assessed at 52 and 72 wk of age. Necropsies were performed on all mortalities 1 wk before and after the WQA sampling. WQAs were analyzed using Mann-Whitney U and Kruskal-Wallis tests for prevalence and Fishers exact tests for severity. There was an effect of rearing, with AVP having shorter claws (P = 0.01), dirtier feathers (P = 0.03), and more keel abnormalities (P < 0.0001) than CCP at placement. For the hens, there were several significant housing system effects across flocks and age periods (all P ≤ 0.05). AV and EC hens had more keel abnormalities than CC hens. They also had fewer foot abnormalities than CC hens, although those in AV hens were more severe. AV hens had consistently dirtier feathers than EC and CC hens. While AV hens had the best overall feather cover, feather loss patterns suggested that loss was due to head pecking for AV, whereas in EC and CC it was due to cage abrasion. The necropsy findings and the WQA results were similar, except that the WQA failed to find enteritis at 19 wk, although it was detected in the necropsies during this sampling period. These results show that the WQA is a useful tool for detecting hen condition differences across housing systems.

Effect of antibiotics on in vitro and in vivo avian cartilage degradation.

SUMMARY. Antibiotics are used in the livestock industry not only to treat disease but also to promote growth and increase feed efficiency in less than ideal sanitary conditions. However, certain antibiotic families utilized in the poultry industry have recently been found to adversely affect bone formation and cartilage metabolism in dogs, rats, and humans. Therefore, the first objective of this study was to determine if certain antibiotics used in the poultry industry would inhibit in vitro cartilage degradation. The second objective was to determine if the antibiotics found to inhibit in vitro cartilage degradation also induced tibial dyschondroplasia in growing broilers. Ten antibiotics were studied by an avian explant culture system that is designed to completely degrade tibiae over 16 days. Lincomycin, tylosin tartrate, gentamicin, erythromycin, and neomycin sulfate did not inhibit degradation at any concentration tested. Doxycycline (200 µg/ml), oxytetracycline (200 µg/ml), enrofloxacin (200 and 400 µg/ml), ceftiofur (400 µg/ml), and salinomycin (10 µg/ml) prevented complete cartilage degradation for up to 30 days in culture. Thus, some of the antibiotics did inhibit cartilage degradation in developing bone. Day-old chicks were then administered the five antibiotics at 25%, 100%, or 400% above their recommended dose levels and raised until 21 days of age. Thiram, a fungicide known to induce experimental tibial dyschondroplasia (TD), was given at 20 ppm. Birds were then killed by cervical dislocation, and each proximal tibiotarsus was visually examined for TD lesions. The results showed that none of these antibiotics significantly induced TD in growing boilers at any concentration tested, whereas birds given 20 ppm thiram had a 92% incidence rate.

CYCLOPHOSPHAMIDE (CYTOXAN)-INDUCED HEMATOLOGIC ALTERATIONS IN SPECIFIC-PATHOGEN-FREE CHICKENS

Cyclophosphamide (Cytoxan) was given at 75 mg/kg body weight via daily intramuscular injections for 4 days to 3-week-old specific-pathogen-free (SPF) chickens in an attempt to determine if heteropenia could be induced in chickens. Control birds were given a like quantity of phosphate-buffered saline, the diluent for Cytoxan. Peripheral blood heterophil numbers were determined and monitored by total leukocyte and differential cell counts. Birds were grouped in pairs on day 0 based on total leukocyte count. The number of heterophils each bird had on day 0 served as a baseline heterophil count for that bird. Thereafter heterophil numbers were determined on the last day of drug treatment and every other day until blood heterophil numbers were 20% of that birds baseline heterophil count (heteropenia). The effects of Cytoxan on trachea, lung, liver, kidney, bursa of Fabricius, bone marrow, spleen, and thymus were determined by microscopic examination of those tissues collected the day following heteropenia. Cytoxan had no effect on trachea, lung, liver, kidney, and thymus. Bursa of Fabricius and spleen had decreased amounts of lymphoid aggregates. Bone marrow of Cytoxan-treated chickens was hypocellular. The study was then repeated to determine the reversibility of Cytoxan-induced heteropenia. Cytoxan-treated birds were allowed to recover until blood heterophil numbers equaled or exceeded those of control birds. Cytoxan, through bone marrow suppression, induced a reversible heteropenia that developed between treatment days 10 and 12. In addition, Cytoxan induced a reversible lymphocytopenia between days 4 and 10 and a regenerative anemia between days 8 and 10. The ability to produce heteropenia in SPF chickens will allow the use of a heteropenic model for further study of the heterophils contribution to the inflammatory response.