Erin M. Brannick

Layer hens (egg-laying chickens) and broiler breeders (breeding stock for meat-producing chickens) are crucial to the world's food supply as a reliable source of protein. They are also an emerging animal model for the study of human reproductive disease. As the field of poultry research develops, the health and function of the layer hen and broiler breeder ovary will be an important point of study for both agricultural and biomedical researchers. One of the challenges presented by this emerging interest is the need for replicable techniques that all researchers can employ in ovarian specimen collection. In particular, a detailed visual process must be established to define the proper separation of the specialized granulosa and theca cell layers from hen follicles to achieve agreement and consistency among researchers. This study describes the extraction of preovulatory follicles and ovary tissue in white leghorn hens of prime reproductive age. The separation of these follicles is performed under cold, liquid conditions to congeal the yolk for easier manipulation and to prevent the follicle's own weight from tearing apart cell layers during the separation process. Once the separation is complete, the desired cell layers can be further digested for tissue culture approaches or can be cryopreserved for genomic and proteomic analyses.

Layer hens (egg-laying chickens) and broiler breeders (breeding stock for meat-producing chickens) are crucial to the world's food supply as a reliable source of protein. They are also an emerging animal model for the study of human reproductive disease. As the field of poultry research develops, the health and function of the layer hen and broiler breeder ovary will be an important point of study for both agricultural and biomedical researchers. One of the challenges presented by this emerging interest is the need for replicable techniques that all researchers can employ in ovarian specimen collection. In particular, a detailed visual process must be established to define the proper separation of the specialized granulosa and theca cell layers from hen follicles to achieve agreement and consistency among researchers. This study describes the extraction of preovulatory follicles and ovary tissue in white leghorn hens of prime reproductive age. The separation of these follicles is performed under cold, liquid conditions to congeal the yolk for easier manipulation and to prevent the follicle's own weight from tearing apart cell layers during the separation process. Once the separation is complete, the desired cell layers can be further digested for tissue culture approaches or can be cryopreserved for genomic and proteomic analyses.

Current diagnostic methods for wooden breast and white striping, common breast muscle myopathies of modern commercial broiler chickens, rely on subjective examinations of the pectoralis major muscle, time-consuming microscopy, or expensive imaging technologies. Further research on these disorders would benefit from more quantitative and objective measures of disease severity that can be used in live birds. To this end, we utilized untargeted metabolomics alongside two statistical approaches to evaluate plasma metabolites associated with wooden breast and white striping in 250 male commercial broiler chickens. First, mixed linear modeling was employed to identify metabolites with a significant association with these muscle disorders and found 98 metabolites associated with wooden breast and 44 metabolites associated with white striping (q-value < 0.05). Second, a support vector machine was constructed using stepwise feature selection to determine the smallest subset of metabolites with the highest categorization accuracy for wooden breast. The final support vector machine achieved 94% accuracy using only 6 metabolites. The metabolite 3-methylhistidine, which is often used as an index of myofibrillar breakdown in skeletal muscle, was the top metabolite for both wooden breast and white striping in our mixed linear model and was also the metabolite with highest marginal prediction accuracy (82%) for wooden breast in our support vector machine. Overall, this study identified a candidate set of metabolites for an objective measure of wooden breast or white striping severity in live birds and expanded our understanding of these muscle disorders.

Wooden breast syndrome is a widespread and economically important myopathy and vasculopathy of fast growing, commercial broiler chickens, primarily affecting birds with high feed efficiency and large breast muscle yield. To investigate potential systemic physiological differences between birds affected and unaffected by wooden breast, a total of 103 market-age Cobb 500 broilers were sampled for 13 blood parameters and the relative weights of the pectoralis major muscle, pectoralis minor muscle, external oblique muscle, wing, heart, lungs, liver, and spleen. Blood analysis was performed on samples taken from the brachial vein of live birds and revealed significant differences in venous blood gases between affected and unaffected chickens. Chickens with wooden breast exhibited significantly higher potassium (K⁺) and lower partial pressure of oxygen (pO₂), oxygen saturation (sO2), and pH. Additionally, affected males had significantly higher partial pressure of carbon dioxide (pCO₂) and total carbon dioxide (TCO₂) than unaffected males. Wooden breast affected broilers also possessed a significantly heavier pectoralis major muscle and whole feathered wing compared to unaffected broilers. Blood gas disturbances characterized by high pCO₂ and low pH are indicative of insufficient respiratory gas exchange, suggesting that wooden breast affected broilers have an elevated metabolic rate that may also be inadequately compensated due to cardiovascular deficiencies such as poor venous return or respiratory insufficiency. Lung tissues from 12 birds with extreme sO₂ values were subsequently examined to assess whether lung pathology contributed to the observed blood gas disturbance. Comparison of lung morphology between affected and unaffected birds revealed no apparent differences that could contribute to decreased parabronchial gas exchange. However, an interesting finding was the detection of pulmonary phlebitis in one of the wooden breast-affected samples consistent with vascular changes observed in pectoralis major muscle exhibiting the wooden breast phenotype. Our results suggest that the effects of wooden breast are not limited to the pectoralis major muscle and further indicate the importance of research into metabolic changes associated with the myopathy.

Zika virus (ZIKV) is a mosquito-borne flavivirus associated with microcephaly and other neurological disorders in infants born to infected mothers. Despite being declared an international emergency by the World Health Organization, very little is known about the mechanisms of ZIKV pathogenesis or the long-term consequences of maternal ZIKV infection in the affected offspring, largely due to the lack of appropriate rodent models. To address this issue, our lab has developed a working model of prenatal ZIKV infection in rats. In this study, we infected immune competent pregnant female rats with 10⁵–10⁷ PFU of ZIKV (PRVABC59, Puerto Rico/Human/Dec 2015) in order to examine its pathogenesis in the dams and pups. We examined the febrile response and sickness behavior in the dams, in addition to neonatal mortality, microglia morphology, cortical organization, apoptosis, and brain region-specific volumes in the offspring. Here, we demonstrate that pregnant and non-pregnant female rats have a distinct febrile response to ZIKV infection. Moreover, prenatal ZIKV infection increased cell death and reduced tissue volume in the hippocampus and cortex in the neonatal offspring. For the first time, we demonstrate the efficacy and validity of an immunocompetent rat model for maternal ZIKV infection that results in significant brain malformations in the neonatal offspring.

Wooden Breast Disease (WBD), a myopathy in commercial broiler chickens characterized by abnormally firm consistency of the pectoral muscle, impacts the poultry industry negatively due to severe reduction in meat quality traits. To unravel the molecular profile associated with the onset and early development of WBD in broiler chickens, we compared time-series gene expression profiles of Pectoralis (P.) major muscles between unaffected and affected birds from a high-breast-muscle-yield, purebred broiler line. P. major biopsy samples were collected from the cranial and caudal aspects of the muscle belly in birds that were raised up to 7 weeks of age (i.e. market age). Three subsets of biopsy samples comprising 6 unaffected (U) and 10 affected (A) from week 2 (cranial) and 4 (caudal), and 4U and 11A from week 3 (cranial) were processed for RNA-sequencing analysis. Sequence reads generated were processed using a suite of bioinformatics programs producing differentially expressed (DE) genes for each dataset at fold-change (A/U or U/A) >1.3 and False Discovery Ratio (FDR) <0.05 (week 2: 41 genes; week 3: 618 genes and week 4: 39 genes). Functional analysis of DE genes using literature mining, BioDBnet and IPA revealed several biological processes and pathways associated with onset and progress of WBD. Top among them were dysregulation of energy metabolism, response to inflammation, vascular disease and remodeling of extracellular matrix. This study reveals that presence of molecular perturbations involving the vasculature, extracellular matrix and metabolism are pertinent to the onset and early pathogenesis of WBD in commercial meat-type chickens.

Wooden Breast Disease (WBD), a myopathy that frequently affects modern broiler chickens, is a disorder that has been associated with significant economic losses in the poultry industry. To examine tissue changes associated with the onset and early pathogenesis of this disorder, a time-series experiment was conducted using chickens from a high-breast-muscle-yield, purebred commercial broiler line. Birds were raised for up to seven weeks, with a subset of birds sampled weekly. Breast muscle tissues were extracted at necropsy and processed for analysis by light microscopy and transmission electron microscopy. Histologic presentation indicated localized phlebitis with lipogranulomas in Week 1, focal single-myofibril degeneration in Week 2 preceding an inflammatory response that started in Week 3. Lesions in Week 4 were characterized by multifocal to diffuse muscle fibre degeneration, necrosis, interstitial oedema accompanied by increased lipid and inflammatory cell infiltration. Lesions in Weeks 5–7 revealed diffuse muscle degeneration, necrosis, fibrosis and fatty infiltration with lipogranulomas. Ultrastructural examination showed myofibrillar splitting and degeneration, irregular, displaced and degenerated Z-lines, mitochondrial degeneration and interstitial fibrosis with dense regular collagen fibres. This study, therefore, demonstrates that WBD exhibits an earlier onset in modern broilers than when detectable by clinical examination. Further, this study shows that the disease assumes a progressive course with acute vasculitis, lipid deposition and myodegeneration occurring in the earlier stages, followed by a chronic fibrotic phase.

SUMMARY The efficacy of commercially available recombinant herpesvirus of turkeys-infectious bursal disease (rHVT-IBD) virus vaccines was studied in broiler chickens derived from an IBDV-vaccinated breeder flock at 30 wk of age (Trial 1) and 60 wk of age (Trial 2). In parallel, specific-pathogen-free (SPF) white leghorn chickens were used to evaluate vaccine efficacy to control for the effects of maternally derived antibodies (MDA) associated with the broiler chickens. Broilers and SPF leghorns were vaccinated subcutaneously in the neck at 1 day of age with Vaxxitek® HVT+IBD or Vectormune® HVT-IBD vaccines and were placed in isolators. On 10, 14, 18, 22, and 26 days postvaccination (DPV), vaccinated and nonvaccinated broilers and SPF leghorns were bled prior to challenge via the oral-nasal route with infectious bursal disease (IBD) reference strains ST-C, Delaware variant E (Del E), or contemporary field isolates DMV/5038/07 or FF6. Microscopic lesion assessment of the bursa was useful for assessing IBDV ... RESUMEN Eficacia de vacunas recombinantes contra el virus de la enfermedad infecciosa de la bolsa con base en un hespesvirus de los pavos como vector (HVT-IBD) y administradas en pollos de engorde provenientes de una sola parvada de reproductores a las 30 y 60 semanas de edad. Se estudió la eficacia de una vacuna contra la enfermedad infecciosa de la bolsa con un herpesvirus de los pavos recombinante, que está disponible en el mercado (rHVT-IBD) al ser administrada en pollos de engorde provenientes de un lote de reproductoras a las 30 semanas de edad (Ensayo 1) y a las 60 semanas de edad (Trial 2). La parvada de reproductoras estaba vacunada contra la enfermedad de Gumboro. De forma paralela, se utilizaron aves blancas tipo Leghorn libres de patógenos específicos (con las siglas en inglés SPF) para evaluar la eficacia de la vacuna ante el efecto de los anticuerpos maternales (MDA) en los pollos de engorde. Los pollos de engorde y las aves Leghorn libres de patógenos específicos se vacunaron por vía subcut...