Leg health and performance of broiler chickens reared in different light environments

1. The effects of light source and intensity on leg health and performance of female ROSS 308 broiler chickens were investigated in a 2 x 2 experimental design (8 groups of 275 chicks) of two light sources (Osram biolux and Osram warm-white) and two light intensities (5 and 100 clux, adjusted to fowl-perceived illuminance). 2. At 41 d of age, body weight, gait-score, footpad dermatitis and hock-burn were measured on 50 birds from each light environment. In addition, weekly feed intake and body weight were determined on a group basis and mortality was recorded continuously. 3. The light environment did not affect the severity of the gait-score or hock-burns. The risk of moderate to severe lameness and hock-burns increased with body weight. Birds weighing more than 2400 g had an increased probability of moderate footpad lesions in biolux light. 4. Weight and gait-score, as well as gait-score and hock-burn were positively correlated. Podo-dermatitis was weakly correlated with hock-burn, which contradicts earlier findings. The light environment did not affect feed intake, body weight or mortality. 5. The light sources and intensities employed in this study did not adversely affect production or leg health of broiler chickens reared semi-commercially.     

Ixodes frontalis and avian tick-related syndrome in the United Kingdom

OBJECTIVES: This study aimed to characterise tick species responsible for avian tick infestations in the UK, to analyse various risk factors for tick-related syndrome in tick-infested birds and to test samples for the presence of certain tick-transmitted pathogens. METHODS: Ticks, blood, splenic tissue and tick attachment site tissue from birds with attached ticks were requested from veterinarians and wildlife sanctuaries around the UK. Ticks were identified according to standard keys, and samples were analysed via DNA PCR test for Borrelia burgdorferi sensu lato, Babesia species, Bartonella species and Ehrlichia species. RESULTS: Ixodes frontalis was the most commonly identified tick, and an association of adult female I frontalis with tick-related syndrome in birds was demonstrated. Tick infestation was markedly seasonal. I frontalis was found on 32 species of birds. DNA PCR testing was uniformly negative. Of the birds known to have been treated, 75 per cent (nine of 12) survived. CLINICAL SIGNIFICANCE: Tick-related syndrome is a poorly understood syndrome, with sporadic distribution, both geographically and seasonally. This study confirms I frontalis as the most common cause of this syndrome in the UK and identifies some features of the tick life cycle in this country. The benefit of treatment in affected birds is highlighted. Risk factors for tick-related syndrome are examined and preventive strategies discussed.     

Histomorphometry of fragmented medial coronoid process in dogs: a comparison of affected and normal coronoid processes

OBJECTIVE: To determine if fatigue microdamage is associated with fragmented medial coronoid process (FMCP). STUDY DESIGN: Prospective study. ANIMALS: Thirty-eight dogs were admitted for subtotal coronoid ostectomy as treatment for FMCP. Surgical specimens of medial coronoid process (MCP) were retrieved from treated dogs. Normal MCP were collected from 5 age- and breed-matched dogs and 2 age-matched research beagles that were euthanatized for reasons other than elbow disease. METHODS: MCP specimens from affected elbows were classified into 4 groups based on disease severity. Specimens were bulk-stained for microdamage using 1% basic fuchsin, embedded in polymethylmethacrylate and sectioned at 130 microm. Specimens were evaluated using epifluorescent microscopy (425-440 excitation, 475 nm barrier filter) for diffuse damage (D.DX), osteocyte loss, and porosity. Cartilage thickness was evaluated using bright field microscopy. Qualitative observations were also made. RESULTS: MCP specimens from affected elbows had increased D.Dx, increased osteocyte loss, and greater porosity than normal groups. Specimens classified as severe FMCP (Classes 3, 4) had the most fatigue microdamage. Some Class 1 specimens, defined as having no visible fissuring of the articular cartilage (AC), had large microcracks in trabecular bone. CONCLUSIONS: Accumulation of subchondral fatigue microdamage, is associated with MCP fragmentation. Fissuring occurs in the subchondral bone before gross fibrillation of articular cartilage develops. CLINICAL RELEVANCE: Accumulation of fatigue microdamage in the MCP is important in the pathogenesis of FMCP. The underlying cause of this microdamage accumulation must be identified before treatment plans that will prevent further osteoarthritis of the elbow joint can be designed.     

Expression of rabbit interleukin-4 and characterization of its biologic activity on T and B-cells

The purpose of the current study was to express recombinant rabbit IL-4 (rRbIL-4) and to characterize its biological activity. The cDNA of RbIL-4 was cloned into an insect cell expression vector that allowed for constitutive expression in Sf9 cells and incorporated a 6-histidine tag on the recombinant protein for purification. The purified protein corresponded to the predicted size of rRbIL-4 and was recognized by an anti-human IL-4 antibody in immunoblotting. As shown for IL-4 from other species, a dose-dependent proliferative response was observed in T-lymphoblasts cultured with rRbIL-4. rRbIL-4 also induced increased expression of MHC class II molecules on the surface of rabbit B-cells in a dose-dependent manner. These results indicate that we have produced recombinant rabbit IL-4 that exhibits expected biological activity on rabbit B and T-cells.     

Sex steroids level in blood plasma and ovarian follicles of the chimeric chicken

The study was performed to determine the hormonal status of mature germline chimeras obtained by blastodermal cell transfer from chicken embryos of a donor breed [Green-legged Partridgelike breed (GP) x Araucana (AR)] to those of a recipient breed [White Leghorn (WL)] being at the same stage of embryonic development. The egg-laying chimeras and WL hens (control) of the same age were used in the experiment. At first, blood samples were taken from each bird at 0.5, 5, 12.5 and 18.5 h following oviposition. Subsequently, the chimeras and the WL hens were decapitated 1-2 h after ovulation. A stroma and the following follicles were isolated from the ovary: white normal (1-4, 4-6 and 6-8 mm), white atretic and yellow preovulatory follicles (F4-F1). Sex hormones, progesterone (P4), testosterone (T) and oestradiol (E2) in blood plasma and ovarian follicles were determined radioimmunologically. The activity of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the granulosa and theca layers of the follicles was analysed histochemically. In chimeric chickens, a higher level of T in blood plasma during the ovulatory cycle was noticed. However, in the stroma, white prehierarchical and medium-size preovulatory ovarian follicles the level of T was significantly lower. With respect to E2, its elevated levels were found both in blood and in the ovarian follicles. There were no significant differences in P4 concentrations in blood plasma while in ovarian follicles a higher level was observed only in white 6-8 mm follicles. 3beta-HSD activity in granulosa and theca layers of the ovarian follicles in chimeras was not different from that in the WL hens. In conclusion, the results obtained indicate that germline chimeras exhibit significant alterations in sex hormone levels in the ovary and blood plasma, which in turn may affect their reproductive abilities.     

Evaluation of ilial screw loosening after triple pelvic osteotomy in dogs: 227 cases (1991-1999)

OBJECTIVE: To investigate factors influencing screw loosening after triple pelvic osteotomy (TPO) and ischial wire stabilization of the acetabular segment. DESIGN: Retrospective case series. Animals-227 dogs with congenital hip dysplasia or subluxated hip joints. PROCEDURES: Medical records and radiographs of 227 dogs that underwent 332 TPO procedures were evaluated, and data pertaining to screw type, plate position, sacral screw engagement, use of ischial interfragmentary wires, and pelvic alignment were assessed for associations with screw loosening. RESULTS: Complications developed in 96 of the 332 (29%) procedures. Cancellous screws without sacral engagement were associated with the lowest frequency (6%) of loosening, compared with cancellous and cortical screws engaging the sacrum and cortical screws that did not engage the sacrum. Frequency of screw loosening increased when cortical or cancellous screws engaged the sacrum and when cortical screws were used. In dogs that had surgery bilaterally, the first limb on which TPO was performed had a higher frequency of screw loosening than the second limb. Pelvic alignment loss was greatest (5.4 degrees ) when the 3 most cranial screws were loosened. Loss of pelvic alignment was significantly different between dogs that underwent surgery and had complications and those that underwent surgery and did not have complications in association with loosening of 1, 2, and 3 screws. CONCLUSIONS AND CLINICAL RELEVANCE: TPO screw loosening was multifactorial and related to stability of the affected ilium, screw type, and screw position. Placing cancellous screws that do not engage the sacrum in pelvic osteotomy plate positions 1 through 3 may decrease the number of screws that loosen.     

Effect of adrenalectomy on cholecystokinin-8-induced Fos-like immunoreactivity in myenteric neurons and the dorsal vagal complex in rats

OBJECTIVE: To investigate the effect of adrenalectomy on cholecystokinin-8 (CCK-8)-induced Fos-like immunoreactivity (Fos-LI) in the myenteric neurons of the dorsal vagal complex (DVC) in rats. ANIMALS: 16 male Sprague Dawley rats. PROCEDURES: Rats were allocated to 1 of 2 groups and underwent adrenalectomy or a sham adrenalectomy procedure. Rats were challenged with a supraphysiologic dose of CCK-8 (40 microg/kg) or physiologic saline (0.9% NaCl) solution (0.5 mL) administered IP; after 90 minutes, rats were euthanized, and Fos-LI was quantified in the DVC (at the levels of the area postrema, nucleus tractus solitarii, and dorsal motor nucleus of the vagus) and the myenteric neurons of the duodenum and jejunum by use of a diaminobenzidine reaction enhanced with nickel. The Fos-LI-positive cells were counted by use of an automated system and manually in the DVC and intestinal samples, respectively. Counts of Fos-LI in the different hindbrain levels and myenteric neurons were compared between the adrenalectomy--and shamtreated groups and between the CCK-8- and saline solution-treated groups. RESULTS: After adrenalectomy, CCK-8-induced Fos-LI was attenuated only in the myenteric neurons of the duodenum. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that the adrenal gland has a role in the activation of myenteric neurons by CCK-8 in rats.     

Thymic granulomatous lesions in pigs

Rare cases of thymic granulomatous lesions were found in pigs. The lesions consisted of epithelioid cells, multinucleated giant cells, and lymphocytes. Such lesions also were observed in the mesenteric lymph nodes, spleen, kidney, and stomach. The cytoplasm of the majority of giant cells and some epithlioid cells was periodic acid-Schiff (PAS) positive. All cells were positive for vimentin, lysozyme, and desmin. Ultrastructurally, the giant cells were rich in organella and attached to adjacent epithelioid cells by membrane interdigitation. The cells included numerous coated vesicles and granules. No etiologic pathogen, including porcine circovirus type 2, was detected in the lesions. This is the rare case of idiopathic thymic granulomatous lesion in pigs.     

Segregation analysis of blood oxygen saturation in broilers suggests a major gene influence on ascites

1. Blood oxygen saturation (SaO) is a potential indicator trait for resistance to ascites in chickens. 2. The objective of the study was to investigate the genetic architecture of SaO in a meat-type chicken line reared in commercial conditions. 3. Data were collected over 15 generations of selection and were divided into two data sets on the basis of a change in recording age from 6 to 5 weeks of age, approximately halfway through the period. The resulting pedigrees comprised in excess of 90,000 birds each and, on average, 12% of these birds had SaO records. 4. Segregation analyses of SaO were carried out assuming a mixed inheritance model that included a major locus segregating in a polygenic background. 5. The analyses suggest that a major gene is involved in the genetic control of SaO in this line. The putative gene acts in a dominant fashion and has an additive effect of around 0.90 sigma(p), equivalent to a predicted difference in SaO between the two homozygous classes of more than 10%. The frequency of the allele that increases SaO changed from 0.53 to 0.65 from the first to the second set of data, consistent with selection on SaO scores. 6. Using estimated genotype probabilities at the putative major locus, we inferred that it acts in an overdominant fashion on body weight and fleshing score. If the low SaO allele leads to susceptibility to ascites, its combined effects are consistent with it being maintained in the population by a balance of natural selection on fitness nad artificial selection on growth and carcase traits. 7. Even with selection on both SaO and growth traits, the combined genotypic effects would make it difficult to remove the unfavourable low-SaO allele by means of traditional selection without the use of genetic markers.