Characterization of dorsal recumbency syndrome associated with woody breast in broiler flocks from Ontario, Canada.

A dorsal recumbency syndrome (DRS) has been recently described in market-age broiler chickens. Affected broilers fall onto their backs, and are unable to right themselves, and eventually die of cardiopulmonary insufficiency. These broilers are referred to as turtle chickens. A previous report and anecdotal evidence suggest that breast myopathies, such as woody breast (WB), may be associated with DRS due to impaired contractility of the pectoral muscles. In this study, we aimed to provide additional evidence to document DRS in broilers, and its possible association with breast myopathies. A total of 64 broilers (Ross 708), 33 DRS-affected and 31 controls, were culled between 42 and 48 d of age from 3 different commercial farms over 4 visits. All broilers underwent postmortem analysis; breast muscles were scored grossly and/or histologically to determine the presence and severity of myopathies, and sera were used to determine the level of aspartate aminotransferase (AST) and creatine kinase (CK). A gross diagnosis of WB was moderately associated with DRS broilers, and DRS broilers displayed a greater microscopic severity of lesions (P < 0.001) in the Pectoralis major, as typically observed with WB. Levels of AST and CK were greater (P < 0.001) in the sera of DRS-affected compared to control broilers, consistent with muscular damage. The frequency of cardiac changes, such as mild hydropericardium and right ventricular dilation, or severity of microscopic pulmonary lesions, such as edema, were not significantly different between the 2 groups. The odds of DRS increased with the histology score of the P. major (OR = 1.37, 95% CI 1.02-1.85). The data presented in this study support an association between DRS and muscular damage of the P. major, suggesting that WB may predispose broilers to DRS. DRS might be a cause of broiler death, and this syndrome could be responsible for significant financial loss to the farmers and to the whole poultry industry.

Risk factors associated with the colonization of Ontario layer chicken flocks with Brachyspira species.

Brachyspira species are frequent colonizers of the gastrointestinal tract in a variety of domestic animals, including birds. In chickens, Brachyspira species are associated with a clinical condition known as avian intestinal spirochetosis (AIS), a disease characterized by chronic diarrhoea, weight loss, low egg production, and faecal-stained eggs. The purpose of this study was to identify risk factors associated with the presence of Brachyspira species in Ontario layer chicken flocks. Pooled faecal samples were collected from 89 flocks from 58 farms between August 2010 and February 2011; 52 flocks were classified as dirty flocks (history of downgrades for dirty eggs) and 37 were classified as clean flocks (no history of downgrades for dirty eggs). A questionnaire related to management, biosecurity practices, and antimicrobial use was administered prior to sample collection. Using real-time polymerase chain reaction; 63.5% of the dirty flocks and 24.3% of the clean flocks were positive for Brachyspira species. A logistic regression model with a random effect for farm showed that the odds of Brachyspira species for flocks ≥ 60 weeks of age were higher than for flocks ≤ 34 weeks (OR=9.3; P=0.014). The odds of Brachyspira species in flocks housed in A-frame cages with manure curtains (OR=20.0; P=0.002) and flocks from multi-age farms (OR=8.5; P=0.001) were higher than for flocks in cage-stacked houses and from single-age farms, respectively. The odds of Brachyspira species for flocks housed in barns ≥ 30 years old was lower than for flocks housed in barns ≤ 14 years old (OR=0.1; P=0.002). The calculated intra-class correlation coefficient was 5.6 × 10(-14); the notably low proportion of variation among farms after the fixed effects were included in the model suggests that the farm-level variable (multi-age farm) included in the final model accounted for most of the farm-to-farm variation in Brachyspira presence. Therefore, it is recommended that strict biosecurity, and between-flock decontamination efforts to reduce the infection pressure, be followed on farms with multiple flocks of different ages to avoid transmission of the bacteria between flocks.

Specific Heats of Oxygen at Coexistence.

Specific heats of saturated liquid, along the coexistence path, are useful for computing thermodynamic properties throughout the compressed liquid phase. We report 86 experimental heat capacities of oxygen for the two-phase system, liquid plus vapor, from the triple-point to near the critical-point and corresponding derived values for the liquid phase. These results are represented by a formula which can be integrated for heat absorbed and for entropy. The changes in value of internal energy, enthalpy, and entropy of the saturated liquid are tabulated from the triple-point to the critical-point.

Specific Heats Cv of Fluid Oxygen from the Triple Point to 300 K at Pressures to 350 Atmospheres.

Experimental specific heats at constant volume for oxygen in single phase domains are reported from the triple point to 300 K at pressures to 350 atmospheres. An empirical equation with seven constants describes these specific heats over the entire domain of ρ-T coordinates to within the experimental accuracy of 1 to 2 percent. Values for the terminal slopes of PVT isochores at the coexistence boundary, (∂P/∂T) υ , are derived for the liquid.