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.

Prevalence of parvovirus in Minnesota turkeys.

Poult enteritis syndrome (PES) is characterized by enteritis and decreased body weight gain in growing turkey poults between one d and 7 wk of age. Another syndrome called light turkey syndrome (LTS) causes a decrease in body weight of adult tom turkeys in Minnesota leading to huge economic losses. Reovirus, rotavirus, and astrovirus have been found in LTS and PES flocks in Minnesota. We tested 80 fecal pools collected from four LTS flocks and 35 fecal pools from non-LTS flocks for the presence of parvovirus. In addition, 116 fecal and meconium samples from turkeys submitted to the Minnesota Veterinary Diagnostic Laboratory (MVDL) also were tested. The samples were tested by PCR using primers for the non-structural 1 (NS1) gene of parvovirus. Of the 80 samples from LTS flocks, 41 were positive for parvovirus while 20 of 35 samples from non-LTS flocks were positive. The prevalence of parvovirus in fecal samples submitted to MVDL was relatively low; only five of the 116 pools were positive. The partial NS1 gene sequences from LTS and non-LTS samples showed 98 to 100% nt identity except for one divergent turkey parvovirus (TuPV) strain that revealed 90% identity and clustered with chicken-like parvoviruses. The presence of this divergent strain suggests circulation of a recombinant strain of TuPV in Minnesota turkeys. Our results indicate that TuPVs are circulating in both LTS and non-LTS flocks of turkeys in Minnesota, and further experimental studies are indicated to study the role of TuPV in LTS.

Differential diagnosis of infectious laryngotracheitis from other avian respiratory diseases by a simplified PCR procedure.

A simple polymerase chain reaction (PCR)-based procedure was developed for the detection of avian infectious laryngotracheitis virus (ILTV) in chicken trachea, chorio-allantoic membrane (CAM), infected hepatoma cells and infectious cell culture supernatant. Samples were prepared by dilution in distilled water. After boiling and low speed centrifugation, samples were used for PCR analysis with two primers without special labeling. The PCR analysis for ILT virus could be completed in less than 8 h. Standard agarose gel electrophoretic analysis of the PCR products revealed a prominent band of 300 base-pairs in samples from ILTV-infected specimens, but not from specimens containing Newcastle disease virus, infectious bronchitis virus, avian adenovirus, fowlpox virus, Pachecoz or Marek's disease virus. One single ILTV infected cell or 10 plaque forming units of ILTV could be detected with this procedure. The procedure can be used for the identification of ILTV and the differentiation of ILTV from other avian respiratory tract infectants.

Financial aspects of clinical education to facilities.

The financial aspects of clinical education for full-time junior and senior physical therapy students as related to facilities offering clinical affiliatins were determined. A questionnaire concerning supervisory expenses, student support, direct and indirect costs returned by 35 facilities of all types provided the basic information. Comparisons of costs and revenues were made for junior and senior students separately and for facilities according to type, size,and personnel involved in student supervision.

Effect of induced molting on the severity of intestinal lesions caused by Salmonella enteritidis infection in chickens.

A study was conducted to describe the intestinal lesions caused by Salmonella enteritidis infection in 20-, 40-, and 74-week-old white leghorn chickens that were undergoing a feed deprivation-induced molt. The chickens were infected on the fourth day after feed was removed. At 4 days postinfection (8 days of feed deprivation), cecal and cecal tonsil inflammation was significantly greater in molted infected chickens than in unmolted infected chickens. The cecal lamina propria and epithelium of molted infected chickens contained heterophilic infiltrates, and there were heterophils and sloughed epithelial cells in cecal lumina. Colonic inflammation, consisting of heterophils infiltrating lamina propria and epithelium, occurred more often in molted infected chickens than in unmolted infected chickens. Immunoperoxidase staining of intestinal sections from 20- and 40-week-old chickens revealed S. enteritidis antigen in the lamina propria of cecum, cecal tonsil, and occasionally the colon of molted infected chickens. The character of the S. enteritidis-induced intestinal lesions associated with molting was similar for different ages of birds.

Effect of Vibrio cholerae toxin on oral immunization of chickens.

Cholera toxin from Vibrio cholerae has been shown to increase the secretory immune response when given orally with some antigens in mice and rabbits. The present study was designed to determine if cholera toxin was also an effective mucosal adjuvant in chickens. Tetanus toxoid was chosen as a model antigen, and response was measured by enzyme-linked immunosorbent assays of intestinal excreta, bile samples, and serum samples. Chickens given 20 micrograms of tetanus toxoid had a significant suppression of response when 20 or 50 micrograms of cholera toxin was given. Chickens given 100 micrograms of tetanus toxoid appeared to be mucosally tolerant, but there was apparent abrogation of the mucosal tolerance when 20 or 50 micrograms of cholera toxin was given. Cholera toxin apparently failed as a mucosal adjuvant in chickens but may have some anti-mucosal tolerogenic effect.

Use of pilocarpine-induced alimentary secretions to measure intestinal shedding of Salmonella enteritidis in chickens.

A technique has been developed that uses the parasympathomimetic drug pilocarpine to induce alimentary secretions in chickens for measuring local immune responses to Salmonella enteritidis strain SE6. A study was conducted to determine if these secretions could also be used to detect intestinal SE6 shedding. White leghorn chickens infected with 1 x 10(9) SE6 were samples weekly using cloacal swabs, and the isolation rates from these samples were compared with alimentary secretions induced by oral administration of phosphate-buffered saline followed 45 minutes later with an intraperitoneal injection of 5% pilocarpine. At 9 days postinfection, isolation rates from the alimentary secretions were significantly higher than isolation rates from the swabs, and by day 16 they were double those from the swabs. In separate small experiments, alimentary secretions induced by pilocarpine alone also had significantly more SE6 isolations than did cloacal swabs on two of three sampling times examined. Direct culture of feces resulted in numerically but not significantly greater SE6 isolations than did cloacal swabs on two of three sampling times. These results indicate that induced intestinal material is a better sample source than cloacal swabs for detecting S. enteritidis intestinal infections in chickens and could have many applications in intestinal pathogenesis research.

Use of a pilocarpine-based lavage procedure to study secretory immunoglobulin concentration in the alimentary tract of White Leghorn chickens.

A lavage procedure was used to study the kinetics of alimentary fluid IgA concentration in 15 specific-pathogen-free white leghorn chickens for 8 weeks post-hatch. Lavage solution was administered orally and collected from the distal alimentary tract following an intraperitoneal injection of pilocarpine. Concentrations of IgA, quantitated by enzyme-linked immunosorbent assay, were more than 0.04 mg/ml by 3 weeks and were negligible before this age. This level gradually increased over the next 5 weeks, peaking at nearly 0.4 mg/ml at 8 weeks of age. Alimentary lavage was easy to perform, required no necropsy or surgical manipulation, and facilitated repeated collection of alimentary fluid from live birds. Repeated lavage did not alter concentrations of IgA and IgG in alimentary fluid, and concentrations of IgA and IgG in alimentary fluid were stable during incubation at 37 C for 24-48 hr.

Microbiological and histopathological effects of an induced-molt fasting procedure on a Salmonella enteritidis infection in chickens.

A study was undertaken to determine if a 2-week feed-removal protocol, as is used by industry to induce a molt in aging hens, would affect the course of a Salmonella enteritidis infection. White leghorn hens aged 69-84 weeks were deprived of feed to induce a molt, and on day 4 of the fast, the birds were orally infected with 5 x 10(6) S. enteritidis. S. enteritidis organisms were enumerated in the spleen on day 6 and from the alimentary tract on days 7, 14, 21, 28, and 35. Little difference was detected in numbers of S. enteritidis from spleens of molted and unmolted hens. Significantly more molted hens shed detectable intestinal S. enteritidis than unmolted hens on day 14 (one of two trials) and day 21 (one of two trials). Intestinal levels of S. enteritidis were increased 100- to 1000-fold in the molted birds on day 7 (one of two trials) and day 14 (two of two trials), and many of the hens exhibited bloody alimentary secretions. Histological examination of the intestinal tract of S. enteritidis-infected molted hens showed increased inflammation in the epithelium and lamina propria of colons and ceca, compared with unmolted infected hens.

Microbiological analysis of the early Salmonella enteritidis infection in molted and unmolted hens.

A study was conducted in which the early kinetics (4 hr to 96 hr) of an infection by Salmonella enteritidis in older white leghorn hens was examined, and a molt was induced through withholding feed to determine its effect on the progression of this infection. Molted and unmolted hens were orally infected with 5-10 x 10(6) S. enteritidis on day 4 of the feed removal. At 4, 24, 48, 72, and 96 hr postinfection, liver, spleen, ileum, colon, cecum, and feces were removed from six hens per group and sampled for the presence of the challenge organism. By 24 hr postinfection, S. enteritidis was most prevalent in the cecum and feces of unmolted hens, and this prevalence continued throughout the experimental period. In molted hens, however, S. enteritidis could be detected in a high percentage (90-100%) of colon, cecum, and feces samples at 24 to 96 hr postinfection and in 67% or more of ileum samples at 48 to 96 hr postinfection, indicating a much wider distribution of the S. enteritidis along the intestinal tract than in unmolted hens. The numbers of S. enteritidis recovered from these alimentary samples were also significantly higher in molted than unmolted hens. S. enteritidis could not be detected in livers or spleens of either treatment group at 4 or 24 hr postinfection. At 48, 72, and 96 hr postinfection, 50% or more of the livers and spleens in both the molted and unmolted hens were positive for the challenge organism, but significantly more S. enteritidis was recovered from the organs of the molted hens at these three sampling times.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis of myeloid leukosis induced by a recombinant avian leukosis virus in commercial white leghorn egg laying flocks.

Commercial white leghorn egg layer flocks being used to produce fertile eggs for human vaccine production exhibited dramatically low peaks in egg production, two to four times higher than normal weekly mortality, and high numbers of cull, nonlaying birds after the onset of sexual maturity. These lower production characteristics could not be associated with management-related problems. Gross lesions of cull and fresh dead birds necropsied showed approximately 60% lacked ovarian activity and had lesions of a bacterial bursitis or synovitis, whereas the other 40% had tumors of the viscera but not of the bursa of Fabricius. Histologic examination of tumor-containing tissues showed lesions typical of myelocytomatosis. The diagnosis of myeloid leukosis was confirmed by the isolation of a recombinant avian leukosis virus (ALV) containing the LTR of subgroup J and the envelope of subgroup B ALV. A positive polymerase chain reaction with primers specific for the 3' untranslated region LTR confirmed the presence of LTR of ALV-J. The source of infection with this recombinant ALV was not determined; however, it is likely that commingling of the day-old egg-type chicks with ALV-J-infected meat-type chicks in a common hatchery had contributed to this outbreak.

The effects of induced molting on the severity of acute intestinal inflammation caused by Salmonella enteritidis.

This study describes and compares early inflammation caused by Salmonella enteritidis in molted and nonmolted hens. Adult white leghorn chickens were orally infected with Salmonella enteritidis 4 days after feed removal. At 2, 4, 8, 10, 24, 48, 72, and 96 hr after infection, the hens were euthanatized, and the duodenum, jejunum, ileum, cecum, and colon were evaluated by light microscopy. Two trials were conducted, and in both trials inflammation occurred more frequently and was significantly greater in the cecum and colon of molted-infected hens compared with nonmolted-infected hens beginning at 8 hr after infection. In one trial, inflammation was more severe in the ileum of molted-infected hens compared with nonmolted-infected hens. Results indicated that molting by feed deprivation shortened the time of onset and increased the severity of acute intestinal inflammation caused by Salmonella enteritidis.

Applying tests for specific yolk antibodies to predict contamination by Salmonella enteritidis in eggs from experimentally infected laying hens.

Detecting Salmonella enteritidis contamination in eggs has become the cornerstone of many programs for reducing egg-borne disease transmission, but egg culturing is time consuming and laborious. Preliminary screening tests are thus generally applied to minimize the number of flocks from which eggs must be cultured. The usefulness of such tests is directly proportional to both their detection sensitivity and their ability to predict the likelihood of egg contamination. In the present study, samples were collected for 24 days after groups of laying hens were orally inoculated with S. enteritidis. Eggs from each hen were cultured for S. enteritidis in the contents and samples of egg yolk were diluted and tested for specific antibodies to S. enteritidis flagella using both experimental and commercially available enzyme-linked immunosorbent assay (ELISA) methods. Samples of voided feces were also collected regularly from each bird and cultured for S. enteritidis. Although fecal shedding and egg yolk antibody production followed opposite patterns over time (fecal shedding was decreasing as egg yolk antibody titers were increasing), tests for both parameters were effective in predicting whether particular hens would lay contaminated eggs. Among hens that laid at least one egg contaminated by S. enteritidis, 82% were detected as infected by fecal culturing and 96% by the experimental egg yolk ELISA test. Using easily collected samples, egg yolk antibody testing offers a rapid and effective screening method for identifying S. enteritidis-infected laying flocks that might lay contaminated eggs.

Microsphere uptake by the intestine of White Leghorn chickens.

A study was conducted to determine the effective size for latex microsphere uptake in the intestine of white leghorn chickens. Three trials were conducted in which ligated intestinal segments of anesthetized 8-wk-old chickens were injected with 0.2-, 0.5-, 2-, 6-, 10-, or 20-mu diameter fluoresceinated latex microspheres. Microspheres were counted in brush border, epithelium, and lamina propria of each intestinal segment, liver, and spleen. After 1 hr, the 0.2-, 0.5-, and 2-mu microspheres were oriented along the brush border of epithelial cells and microsphere uptake into the epithelium and lamina propria was observed in the duodenum, ileum, cecum, cecal tonsil, and colon. Uptake of microspheres of 6, 10, and 20 mu diameter into epithelium and lamina propria was not observed in any intestinal segment. Also, no microspheres of any diameter were observed in sections of liver and spleen to suggest that there was no appreciable entry of microspheres into the bloodstream within 1 hr after administration. The results indicated that uptake of microspheres by the chicken intestine is a size-dependent process with microspheres < or = 2 mu being taken up to an equal extent by most segments of intestine.

The effect of route of inoculation on the virulence of raptorial Pasteurella multocida isolates in Pekin ducks (Anas platyrhynchos).

The purpose of this study was to determine the virulence of raptorial Pasteurella multocida for ducks and the effect of various routes of inoculation on virulence. Four-week-old Pekin ducks (Anas platyrhynchos) were challenged with one of three raptorial isolates (RTHA-2, RTHA-4, or WESO-1) by one of five inoculation routes (intranasal, intraocular, intravenous, oral, and subcutaneous). Ducks were monitored daily for mortality until 2 wk postchallenge. Results indicated that the intravenous route caused the most mortality for all isolates and that significant variation existed in the virulence among the sources of P. multocida, with WESO-1 causing the least mortality of the isolates tested.

Palatability of bird repellents to Rattus norvegicus.

The palatability to captive, mostly laboratory-bred, Norway rats (Rattus norvegicus) of cereal-based baits containing 0.02 g kg-1 brodifacoum, with and without bird-repellent additives, was compared in a no-choice experimental design. Methyl anthranilate (25 g kg-1), dimethyl anthranilate (25 g kg-1) and cinnamamide (2.5 g kg-1) reduced bait consumption by the rats, but all except one rat ate enough bait to receive a lethal dose. Cinnamamide (1 g kg-1), ortho-aminoacetophenone (0.1 g kg-1) and tannic acid (20 g kg-1) did not reduce bait consumption and all rats died after eating baits. The concentration of cinnamamide palatable to rats has only a low and short-lived repellency to birds, so it does not warrant further investigation. However, ortho-aminoacetophenone and tannic acid should now be field-tested for palatability to all three rat species in New Zealand and for repellency to native New Zealand birds.

Development of an enzyme-linked immunosorbent assay to detect IgG, IgM, and complement (C3) on canine erythrocytes.

An ELISA was used to detect IgG, IgM, and complement (C3) on the surface of canine erythrocytes. Erythrocytes were placed in wells of a microtitration plate and incubated with affinity purified, alkaline phosphatase-conjugated anti-canine IgG, IgM, or C3. Results of the ELISA were compared with the direct antiglobulin test (DAT) by preparing standard reference curves from canine blood type A erythrocytes that had been incubated with serial dilutions (1:2 to 1:8, 192) of canine anti-A serum. The ELISA detected increased erythrocyte-bound immunoglobulin and complement at two- to fourfold dilutions greater than those required for positive results with the DAT. The ELISA required small sample and reagent volumes and detected lower concentrations of immune components than did the DAT.

Effects of body position and ventilation/compression ratios during cardiopulmonary resuscitation in cats.

Eighteen cats were anesthetized and were randomly assigned to 2 groups (9 cats/group). Cardiopulmonary resuscitation (CPR) was performed on each cat, with the cat in dorsal (group 1) or lateral (group 2) recumbency, by administering 5 external cardiac compressions/1 interposed (diastolic) ventilation (American Heart Association [AHA] technique; n = 3 cats/technique), simultaneous compression and ventilation (SCV; n = 3 cats/technique), or SCV with 1 interposed (diastolic) ventilation every tenth compression (SCV/DV; n = 3 cats/technique). Fourteen of the 18 cats were resuscitated. Central aortic and venous pressures were determined concurrently with lead II electrocardiography. Arterial blood samples were collected during the base-line period (after pressure fluctuations had stabilized, with the cats spontaneously breathing room air), 2.5 minutes after the onset of arrest (defined as the cessation of aortic pressure fluctuations), and after 10 minutes of CPR. Arterial blood gas values during the base-line period or during the period of arrest were not significantly different between group-1 and group-2 cats. After CPR, arterial pH and bicarbonate values were not significantly different between groups or between technique categories. The PaCO2 values were significantly lower in cats resuscitated by SCV or by SCV/DV than in cats resuscitated by AHA (P less than 0.05). The PaO2 values were significantly (P less than 0.001) higher in group-2 cats than in group-1 cats and were significantly (P less than 0.001) different between each technique category, with cats resuscitated by AHA having the lowest PaO2 and cats resuscitated by SCV/DV having the highest PaO2. Body position, CPR technique, sex, weight, or arterial blood gas values after CPR were not predictors of successful resuscitation.

Bacterial enteritides of poultry.

Enteric bacterial infections in poultry pose a threat to intestinal health and can contribute to poor feed efficiency and livability of a flock. A variety of enteric bacterial diseases are recognized in poultry. Three of these bacterial diseases, necrotic enteritis, ulcerative enteritis, and spirochetosis, primarily infect the intestine, whereas other bacterial diseases, such as salmonellosis, colibacillosis, mycobacteriosis, erysipelas, and fowl cholera, affect a variety of organ systems in addition to the intestine. Diagnosis of bacterial enteritis requires monitoring of clinical signs in the flock and proper use of diagnostic methods such as necropsy, histopathology, bacteriology, and serology.

Effect of induced molting on the recurrence of a previous Salmonella enteritidis infection.

Previous work in the authors' laboratory had shown that hens infected with Salmonella enteritidis (SE) during the feed removal phase of an induced molt shed significantly more SE and more readily transmitted SE to uninfected hens in adjacent cages when compared with unmolted hens. A study was conducted to examine the effect of induced molting on the recurrence and horizontal transmission of a previous SE infection. Hens aged 59 and 69 wk in Trials 1 and 2, respectively, were infected with SE and then molted 21 days later. In Trial 1, more molted hens were SE-culture-positive on Days 38 (P < or = .005) and 45 (P < or = .005) postinfection, and these hens shed more SE on these days (P < or = .05 and P < or = .005, respectively) than unmolted hens. Horizontal transmission of SE to previously uninfected but contact-exposed hens in adjacent cages was also higher in the molted group than the unmolted group on Days 38 (P < or = .05) and 45 (P < or = .001). Molted, contact-exposed hens also shed significantly more SE than unmolted hens. In Trial 2, the molted infected hens shed progressively more SE than the unmolted hens but the differences were not significant. However, more molted contact-exposed hens became SE-positive at Day 31 (P < or = .05) and 38 (P < or = .005) and also shed more SE on these days (P < or = .05 and P < or = .01), respectively) than the unmolted hens. Serum and intestinal antibody titers to SE were also examined in Trial 2. Molting appeared to exert no effect on the serum SE titers, but antibody titers in the alimentary tract were lower in the molted hens than the unmolted hens on Days 45 (P < or = .005) and 52 (P < or = .05). In Trial 1, three of eight molted directly infected hens and two of eight molted contact-exposed hens produced any SE-contaminated eggs. In Trial 2, no SE-contaminated eggs were produced.