White Leghorn Chickens Research Articles

Differential expression of ASIP transcripts reveals genetic mechanism underpinning black-tail independence from body plumage in yellow-bodied chickens.

The genetic foundation of chicken body plumage color has been extensively studied. However, little attention has been paid to the inheritance patterns and molecular mechanisms underlying the formation of distal feather colors (tail and wingtip). Differences in these colors are common; for example, the Chinese Huiyang Beard chicken has black tail feathers, but yellow body plumage. Here, the hybrid offspring of Huiyang Beard and White Leghorn chickens were used to study the inheritance patterns of tail-feather color. The expression levels of pigment genes in differently colored feather follicles were analyzed using quantitative real-time PCR. The results showed that genetic regulation of tail-feather color was independent of body-plumage color. The Dominant White locus inhibited eumelanin synthesis in tail feathers without affecting the formation of yellow body plumage, whereas the Silver locus had the opposite effect. The expression of agouti signaling protein (ASIP) gene class 1 transcripts was significantly lower in black tail-feather follicles than in yellow body follicles, whereas tyrosinase-related protein 1 (TYRP1) gene expression was significantly higher in black tail feathers. These differentially expressed genes were confirmed to exert an effect on eumelanin and pheomelanin formation in feathers, thus influencing the regulation of chicken tail-feather color. In conclusion, this study lays the foundation for further research on the genetic mechanisms of regional differences in feather color, contributing to a better understanding of plumage pigmentation in chickens.

Differences in the microbiome of the small intestine of Leghorn lines divergently selected for antibody titer to sheep erythrocytes suggest roles for commensals in host humoral response.

For forty generations, two lines of White Leghorn chickens have been selected for high (HAS) or low (LAS) antibody response to a low dose injection of sheep red blood cells (SRBCs). Their gut is home to billons of microorganisms and the largest number of immune cells in the body; therefore, the objective of this experiment was to gain understanding of the ways the microbiome may influence the differential antibody response observed in these lines. We achieved this by characterizing the small intestinal microbiome of HAS and LAS chickens, determining their functional microbiome profiles, and by using machine learning to identify microbes which best differentiate HAS from LAS and associating the abundance of those microbes with host gene expression. Microbiome sequencing revealed greater diversity in LAS but statistically higher abundance of several strains, particularly those of Lactobacillus, in HAS. Enrichment of microbial metabolites implicated in immune response such as lactic acid, short chain fatty acids, amino acids, and vitamins were different between HAS and LAS. The abundance of several microbial strains corresponds to enriched host gene expression pathways related to immune response. These data provide a compelling argument that the microbiome is both likely affected by host divergent genetic selection and that it exerts influence on host antibody response by various mechanisms.

The effect of zinc on the stiffness of chicken lenses

Aims/Purpose: Aquaporins are specialized water channels. A volume change through permeable aquaporins may be necessary for the lens' ability to change shape during accommodation1. This study aimed to determine the effects of zinc2, an agonist that increases aquaporin 0 (AQP0) permeability in oocytes, on the biomechanics of chicken lenses.Methods: White Leghorn chickens (Gallus gallus domesticus, N = 6) were sacrificed at 14 days of age. Both eyes were enucleated and lenses were dissected in Tyrode's solution (TS). One lens from each bird was treated with zinc chloride (80 μg/mL in TS for 15 min, at room temperature; RT), while the other lens (control lens) was incubated in TS (15 min, RT). Lenses were compressed (CellScale Micro Tester G2) to test their biomechanical integrity. For each lens, force‐compression data were generated by the MicroTester G2 software (ver. 1.0.0.1) and fit to a three‐parameter exponential curve with the equation y = y0 + aebx; the unitless b‐coefficient of the exponential equation was used to assess stiffness as it describes how rapidly the force increases as the compression distance increases. B‐coefficients from each curve were extracted and the effects of zinc treated versus control lenses were analysed using a paired t‐test.Results: The b‐coefficient value for zinc‐treated lenses averaged to 4.2 ± 0.8 while the mean value for control lenses was significantly (p = 0.01) lower at 3.2 ± 0.5, indicating that zinc‐treated lenses were stiffer.Conclusions: The compression data show a zinc‐associated increase in lens stiffness. AQP0 typically plays a role in allowing water to enter, but not exit, the lens, therefore zinc may have led to an increase in water content, resulting in stiffer lenses. However, water permeability was not measured in this study, therefore the AQP0‐associated mechanism of lens stiffening cannot be confirmed. Further study is needed to determine zinc's action on the biomechanics of the lens.

Requirements of metabolisable energy, crude protein and methionine for growing white leghorn chicken under tropical condition

Requirements of metabolisable energy, crude protein and methionine for growing white leghorn chicken under tropical condition

Sperm replacement in sperm-storage tubules causes last-male sperm precedence in chickens

ABSTRACT 1. This study elucidated the last-male sperm precedence (LMSP) mechanism in chickens by examining replacement in storage tubules (SSTs) after multiple artificial inseminations (AI) and the effects of seminal plasma (SP) and male breed on sperm replacement in SSTs. 2. Hens were artificially inseminated with fluorescent dye-labelled spermatozoa from White Leghorn (WL) chickens. Secondary AI was conducted 3 d later with sperm labelled with different nuclear fluorescent dye. Percentage of first and second inseminated sperm in SSTs and their logarithmic odds were calculated. The effect of SP on LMSP was examined using (1) Lake’s solution-washed sperm before second insemination, and (2) SP injected continuously after first insemination. Effect of breed difference on sperm replacement was investigated using Barred Plymouth Rock (BP) sperm. 3. Successive WL-sperm inseminations at three-day intervals caused > 70% stored sperm replacement in SSTs. Although SP removal from sperm from second insemination significantly decreased replacement, its intra-vaginal injection did not affect release. Secondary insemination using BP sperm significantly increased replacement. 4. Sperm replacement is a major factor favouring LMSP in domestic chickens. Two fluorescent staining of sperm, and intra-vaginal multiple AI technique have enabled visualisation, differentiation, and quantification of multiple inseminated sperm stored in the SSTs.

Embryonic development of the chick pineal gland throughout the incubation periods.

Birds have a very different pineal gland structure morphologically and cytologically. The structure of the organ shows significant changes during the incubation periods. This study, which follows the embryological development of the pineal gland and makes histomorphometric measurements of the cellular elements that make up the gland parenchyma, is a current reference for studies in these areas. These brains were taken from 24 Babcock White Leghorn chick embryos on the 10th, 13th, 16th and 21st days of incubation. At 10th embryonic day, the pineal recess was in the structure of an elongated pineal canal. Solid rosette-shaped cell clusters were transforming into round vesicles with a small lumen. These vesicles had developed into larger, oval-shaped follicles with a well-defined central lumen. On 13th day, it was observed that the number and development of follicles increased considerably. The pineal gland showed a follicular-solid structure in 16th day embryos. While the mean follicle diameter was determined as 123.46 ± 13.28 μm on the 10th embryonic day, the highest value was measured as 187.62 ± 7.37 μm on the hatching day (p < 0.05). While the mean follicle area had the lowest value in the 10th day embryos, it was determined that this value gradually increased compared to the advancing embryonic days (p < 0.05). As conclusion, it is thought that this study provides new data to the literature about pineal gland development by monitoring the histological and histomorphometric developments of chick pineal gland in different incubation periods.

Effect of four eggshell repair materials on weight loss during incubation of white leghorn chicken eggs.

Egg weight loss during incubation is a key indicator used to monitor successful egg development and is closely related to hatchability and chick survival. Artificial incubation is one of the most important captive breeding techniques used in conservation efforts to bolster avian populations. To repair damage to the eggshell and ensure embryonic viability during incubation, a variety of repair coverings can be applied. This study tested the impact of four repair materials (nail polish, synthetic glue, medical dressing, and molten wax film) on egg weight loss during incubation. We found no impact on weight loss for coverings smaller than 35% of the eggshell surface, nor did we find any differences between covering types. The average egg weight loss decreased as the coverage area increased, and the weight loss did not differ when blunt versus sharp-end coverings were compared. Given the relative insensitivity of egg weight loss and survival to the type of patch material used, we concluded that the selection of material for the purpose of weight loss management could be based on practical considerations, such as ease of application and availability.

Rayless goldenrod (Isocoma pluriflora) poisoning in chicks (Gallus gallusdomesticus)

Rayless goldenrod (Isocoma spp.) and white snakeroot (Ageratina altissima) poison livestock, wildlife and humans. The suggested toxin for both plants is tremetone, a mixture of benzofuran ketones. However, plant tremetone concentrations often do not correlate with poisoning, and they have not been identified in contaminated milk that poisons nursing neonates. This suggests there may be unidentified metabolites or toxins. Previous studies using various cell culture and large animal models have been inconsistent with varying animal response that often require large doses. The objective of this work is to document the toxicity of rayless goldenrod in California white leghorn chicks, a susceptible small animal model, that would require relatively small amounts of plant material or purified toxins. Four groups of 15 chicks were gavaged with finely ground I. pluriflora at rates of 0, 1%, 2% or 3% of their bodyweight per day for 7 days. After 7 exposure days the chicks were euthanized, necropsied and tissues were collected, fixed and examined microscopically. Myocyte damage was evaluated using clinical signs, weight gain, serum biochemical changes, and histologic lesions and scores. The 3% group had focally extensive myocyte degeneration and necrosis most severely affecting leg muscles (semitendinosus, iliotibialis, peroneus longus and gastrocnemius). This was supported by serum biochemical changes and reduced weight gains. These findings indicate young chicks are a sensitive model of toxicity that may be useful to better identify the rayless goldenrod and white snakeroot toxins, including those unidentified toxins of transmammary poisoning.

Comparative analysis of muscle profiles in silky fowl and white Leghorn Chicken: Insights from multi-omics and experimental approaches

Silky fowl is a highly valued breed of chicken with both culinary and medicinal significance. We conducted a comprehensive and integrated proteomic, transcriptomic, and metabolomic analysis to compare silky fowl meat (SFM) with Leghorn chicken meat (LCM). In SFM, 262 differentially expressed proteins (48 up-regulated, 214 down-regulated), 2577 differentially expressed genes (949 up-regulated, 1628 down-regulated), and 198 differentially abundant metabolites (52 up-regulated, 146 down-regulated) were identified. Our studies underscore the notable involvement of SFM in essential amino acid biosynthesis, accompanied by the up-regulation of genes associated with melanogenesis. Several genes exhibited consistent expression patterns with the results derived from real-time quantitative polymerase chain reaction (RT-qPCR). SFM contained higher levels of flavor-enhancing factors (glutathione, glycine, and serine) relative to LCM. Moreover, it harbored the presence of pharmacologically significant metabolites alongside up-regulated genes related to vitamin E metabolism. These multi-omics differences provide a comprehensive framework that lays the groundwork for future investigations into the biological, nutritional, and pharmacological applications of silky fowl.

Vitamin D Alleviates Cadmium-Induced Inhibition of Chicken Bone Marrow Stromal Cells' Osteogenic Differentiation In Vitro.

Vitamin D is a lipid soluble vitamin that is mostly used to treat bone metabolism-related diseases. In this study, the effect of Cd toxicity in vitro on osteogenic differentiation derived from BMSCs and the alleviating effect of lα, 25-(OH)2D3 were investigated. Cell index in real time was monitored using a Real-time cell analyzer (RTCA) system. The activity of alkaline phosphatase (ALP), and the calcified nodules and the distribution of Runx2 protein were detected using ALP staining, alizarin red staining, and immunofluorescence, respectively. Furthermore, the mitochondrial membrane potential and the apoptotic rate of BMSCs, the mRNA levels of RUNX2 and type Ⅰ collagen alpha2 (COL1A2) genes, and the protein expression of Col1 and Runx2 were detected using flow cytometry, qRT-PCR and western blot, respectively. The proliferation of BMSCs and osteogenic differentiation were enhanced after treatment with different concentrations of lα, 25-(OH)2D3 compared with the control group. However, 5 μmol/L Cd inhibited the proliferation of BMSCs. In addition, 10 nmol/L lα,25-(OH)2D3 attenuated the toxicity and the apoptosis of BMSCs treated by Cd, and also promoted the osteogenic differentiation including the activity of ALP, and the protein expression of Col1 and Runx2. lα, 25-(OH)2D3 can alleviate cadmium-induced osteogenic toxicity in White Leghorn chickens in vitro.

A genome-wide association study for the fatty acid composition of breast meat in an F2 crossbred chicken population.

The composition of fatty acids determines the flavor and quality of meat. Flavor compounds are generated during the cooking process by the decomposition of volatile fatty acids via lipid oxidation. A number of research on candidate genes related to fatty acid content in livestock species have been published. The majority of these studies focused on pigs and cattle; the association between fatty acid composition and meat quality in chickens has rarely been reported. Therefore, this study investigated candidate genes associated with fatty acid composition in chickens. A genome-wide association study (GWAS) was performed on 767 individuals from an F2 crossbred population of Yeonsan Ogye and White Leghorn chickens. The Illumina chicken 60K significant single-nucleotide polymorphism (SNP) genotype data and 30 fatty acids (%) in the breast meat of animals slaughtered at 10 weeks of age were analyzed. SNPs were shown to be significant in 15 traits: C10:0, C14:0, C18:0, C18:1n-7, C18:1n-9, C18:2n-6, C20:0, C20:2, C20:3n-6, C20:4n-6, C20:5n-3, C24:0, C24:1n-9, monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). These SNPs were mostly located on chromosome 10 and around the following genes: ACSS3, BTG1, MCEE, PPARGC1A, ACSL4, ELOVL4, CYB5R4, ME1, and TRPM1. Both oleic acid and arachidonic acid contained the candidate genes: MCEE and TRPM1. These two fatty acids are antagonistic to each other and have been identified as traits that contribute to the production of volatile fatty acids. The results of this study improve our understanding of the genetic mechanisms through which fatty acids in chicken affect the meat flavor.

Fecal microbiota transplantation improves chicken growth performance by balancing jejunal Th17/Treg cells

BackgroundIntestinal inflammation has become a threatening concern in chicken production worldwide and is closely associated with Th17/Treg cell imbalance. Several studies described that gut microbiota is significantly implicated in chicken growth by modulating intestinal immune homeostasis and immune cell differentiation. Whether reshaping gut microbiota by fecal microbiota transplantation (FMT) could improve chicken growth by balancing Th17/Treg cells is an interesting question.ResultsHere, the chickens with significantly different body weight from three different breeds (Turpan cockfighting × White Leghorn chickens, white feather chickens, and yellow feather chickens) were used to compare Th17 and Treg cells. qPCR and IHC staining results indicated that Th17 cell-associated transcriptional factors Stat3 and rorγt and cytokines IL-6, IL-17A, and IL-21 were significantly (P < 0.05) higher in the jejunum of low body weight chickens, while Treg cell-associated transcriptional factor foxp3 and cytokines TGF-β and IL-10 were significantly (P < 0.05) lower in the jejunum of low body weight chickens, indicating imbalanced Th17/Treg cells were closely related to chicken growth performance. Transferring fecal microbiota from the healthy donor with better growth performance and abundant Lactobacillus in feces to 1-day-old chicks markedly increased growth performance (P < 0.001), significantly decreased Th17 cell-associated transcriptional factors and cytokines, and increased Treg cell-associated transcriptional factors and cytokines in the jejunum (P < 0.05). Furthermore, FMT increased the abundance of Lactobacillus (FMT vs Con; 84.98% vs 66.94%). Besides, the metabolites of tryptophan including serotonin, indole, and 5-methoxyindoleacetate were increased as well, which activated their receptor aryl-hydrocarbon-receptor (AhR) and expressed more CYP1A2 and IL-22 to maintain Th17/Treg cell balance and immune homeostasis.ConclusionThese findings suggested that imbalanced Th17/Treg cells decreased chicken growth performance, while FMT-reshaped gut microbiota, i.e., higher Lactobacilli, increased chicken growth performance by balancing Th17/Treg cells.Bkgy_kqRX8WcaCpUPJnFa8Video

Reproduction and production performance of improved chickens, their production constraints, and opportunities under Ethiopian conditions.

Chickens have important roles in human food security and social and cultural values throughout the world. The current review focused on improved chickens' reproduction and production performance, their production constraints, and opportunities under Ethiopian conditions. The review covered nine performance traits, thirteen commercial breeds, and eight crossbreds between commercial breeds, and local chicken. The genotypes affected the age of the first egg, eggs per hen per year, and average egg weight. The three exotic breeds with short ages at first egg were Lohmann Brown, Novo Brown, and Potchefstroom Koekoek at 137, 140, and 142 days, respectively. The three genotypes with the highest egg production were Sasso T44, Bovans Brown, and Isa Browns laying 229, 235, and 276 eggs per hen per year. The three with the highest egg weight were Isa Browns, Bovans Brown, and Sasso T44 with their eggs weighing 58.8, 60.3, and 65.6 g each, respectively. Crossbreeding indigenous chicken with exotic breeds improved the age at first egg-lay, eggs per hen per year, and egg weigh. Crossbreeding indigenous chicken with exotic breeds shortened the age at first egg-lay. Crossbred of indigenous chicken with Fayoumi, Rhode Island Red, and White Leghorn reduced age at first egg-lay to 196.0, 198.3 and 224.3 days, respectively. Crossbreeding Dominant Red Barred with indigenous chicken reduced the age at first egg-lay from 137.3 to 130.7 days. Among the crossbred chicken, crossing between local chicken and Fayoumi, White Leghorn, and Yarkon laid the most eggs per hen per year being 119, 120, and 129 eggs, respectively. The crossbreed between Dominant Red Barred, and Horro ecotype aged 41-44 weeks laid eggs weighing 56.3 g. The management practices affected age at first egg with the smallholder production system tending to delay it and reduced the eggs per hen per year and average egg weight. The age at first egg-lay for Bovans Brown breed ranged from 165.6 to 196.2 days under this system. Potchefstroom Koekoek chicken breed reared under this system laid 130.5 to 187.0 eggs per hen per year. When additional feed was provided, Bovans Brown chicken breed increased their egg production from 133.5 to 235.9 eggs per hen per year. The average egg weight was 43.0, 52.1, and 52.5 g for Fayoumi, White Leghorn, and Rhode Island Red chicken, repectivelly, under this system in northern Ethiopia. Most chicken breeds were reared under inadequate management practices resulting in suboptimal performance. Crossbreeding exotic and indigenous chicken breeds and intensifying the management will improve performance. The existence of suitable market demand for chicken products, readily available commercial feeds, and government and private investor involvement are emerging opportunities for enhanced chicken performance in Ethiopia.

Morphological changes in the adrenal glands of chickens under heat stress

Heat stress as a result of hyperthermia and dehydration of the body due to natural or artificial environmental factors negatively affects the well-being of birds. Heat stress factor can lead to significant economic losses in poultry farms due to a decrease in egg production, egg fertilization, hatching and viability of young animals, morphological indicators of eggs, an increase in bird mortality during maintenance and transportation, the occurrence of immunosuppression and metabolic disorders. Pathomorphological changes in the internal organs of birds under heat stress are classified as degenerative changes, necrosis, circulatory disorders, changes in tissue fluid, growth disorders, and inflammation. The adrenal gland affects the number of functional and metabolic processes in the body of birds, its hormones ensure its resistance to heat stress. In the current global warming climate, the study of the morphology of the adrenal gland of birds due to the action of a thermal stress factor is an urgent problem of poultry farming, since its solution contributes to the scientific justification of technologies for growing, using and treating birds. The aim of the study was to identify morphological changes in the adrenal gland of white leghorn chickens aged 3 months under heat stress. Anatomical, morphometric, microscopic and statistical research methods were used in the course of the study. It was found that the indicators of absolute mass and linear dimensions of the adrenal glands of chickens under heat stress increased relative to such indicators in clinically healthy chickens. Microscopically, circulatory disorders (edema, hyperemia, hemorrhages, congestion, thrombosis) were recorded in the adrenal glands of chickens, which on the 4th day of exposure to the heat stress factor were accompanied by activation of regenerative processes (an increase in the number of fibroblasts under the capsule) and secretory activity of endocrinocytes (an increase in the size of interrenal and suprarenal cells). Intense and prolonged stress of the adrenal glands of chickens caused by heat stress led to the withdrawal of their plastic and energy resources, and as a result caused the development of adrenal deficiency on Day 8, which was observed destructive and dystrophic changes in the interrenal and supraranal cells. The obtained data can be used to develop morphofunctional diagnostic and prognostic criteria for the state of both the adrenal glands and the avian organ as a whole under heat stress. In the future of further research-to study the features of the content and localization of nucleic acids, proteins, carbohydrates, lipids in the adrenal glands of chickens under heat stress.

Domestication and social environment modulate fear responses in young chickens

Domesticated species differ from their wild ancestors in a mosaic of traits. Classical domestication theories agree that reactivity to fear and stress is one of the main traits affected. Domesticated species are expected to be less fear and stress prone to than their wild counterparts. To test this hypothesis, we compared the behavioural responses of White Leghorn (WL) chicks to their wild counterparts, Red Junglefowl (RJF) chicks in risk-taking situations. In order to obtain food, the chicks faced an unknown and potentially harmful object at the presence or absence of a social partner. We found that according to our predictions, RJF were more stressed and fearful of the object than the WL. Still, RJF were more explorative than WL. Additionally, the presence of a social partner reduced the fear response in both, but had a stronger effect on RJF. Finally, WL were more food orientated than the RJF. Our results confirmed classical domestication hypotheses of downregulation of the stress system and importance of the social partner in domesticated farm chicken.

Male Gonads Transplantation from Kadaknath Chicken to Chicken and Duck Surrogates

Transplantation of the gonadal tissue of male and female avian species, such as chicken, onto suitable surrogates and production of live offspring has been successfully demonstrated as a strategy for the conservation and re-constitution of valuable chicken germplasm. The main objective of this study was to establish and develop the male gonadal tissue transplantation technology for the conservation of the indigenous chicken germplasm. The male gonads of the Indian native chicken breed, Kadaknath (KN), were transplanted from a day-old donor to a recipient white leghorn (WL) chicken, and Khaki Campbell (KC) ducks, as surrogates. All the surgical interventions were performed under permitted general anaesthesia, and the chicks, upon recovery, were reared with and without immunosuppressant. The recipient surrogates for the donor KN gonads were housed and reared for 10-14 weeks, and post-sacrifice, developed gonadal tissues were harvested to squeeze out the fluid to perform artificial insemination (AI). The AI-entailed fertility test using the recovered seminal extract from the transplanted KN testes from both surrogate species (KC ducks and WL males), used against KN purebred females, remained very close to the percent fertility realised from purebred KN chickens (controls). These initial results revealed from this trial study suggest definitively that, Kadaknath male gonads were readily accepted and grown inside the intra- and inter-species surrogate host, WL chicken and KC ducks, demonstrating a suitable intra- and inter-species donor-host system. Furthermore, the developed transplanted male gonads of KN chicken into the surrogates were found to have the potential to fertilise the egg and give rise to pure-line KN chicks.

Comparison of Immune-Related Gene Expression in Two Chicken Breeds Following Infectious Bronchitis Virus Vaccination.

This study aims to identify the immune-related genes and the corresponding biological pathways following infectious bronchitis virus vaccination in Taiwan Country and White Leghorn chicken breeds. Transcriptomic analyses of the spleen of these two breeds were conducted by next-generation sequencing. Compared to White Leghorn chicken, Taiwan Country chicken showed a significantly higher level of anti-infectious bronchitis virus (IBV) antibodies at 14 and 21 days pos vaccination. At 7 days post vaccination, in the Taiwan Country chicken, higher expression of mitogen-activated protein kinase 10, Major histocompatibility complex class 1, and V-set pre-B cell surrogate light chain 3 were found. In contrast, the White Leghorn chicken had a high expression of interleukin 4 induced 1, interleukin 6, and interleukin 22 receptor subunit alpha 2. These findings have highlighted the variations in immune induction between chickens with distinct genetic background and provided biological pathways and specific genes involved in immune responses against live attenuated IBV vaccine.

Dumbbell-shaped brains of Polish crested chickens as a model system for the evolution of novel brain morphologies.

The evolutionary history of vertebrates is replete with emergence of novel brain morphologies, including the origin of the human brain. Existing model organisms and toolkits for investigating drivers of neuroanatomical innovations have largely proceeded on mammals. As such, a compelling non-mammalian model system would facilitate our understanding of how unique brain morphologies evolve across vertebrates. Here, we present the domestic chicken breed, white crested Polish chickens, as an avian model for investigating how novel brain morphologies originate. Most notably, these crested chickens exhibit cerebral herniation from anterodorsal displacement of the telencephalon, which results in a prominent protuberance on the dorsal aspect of the skull. We use a high-density geometric morphometric approach on cephalic endocasts to characterize their brain morphology. Compared with standard white Leghorn chickens (WLCs) and modern avian diversity, the results demonstrate that crested chickens possess a highly variable and unique overall brain configuration. Proportional sizes of neuroanatomical regions are within the observed range of extant birds sampled in this study, but Polish chickens differ from WLCs in possessing a relatively larger cerebrum and smaller cerebellum and medulla. Given their accessibility, phylogenetic proximity, and unique neuroanatomy, we propose that crested breeds, combined with standard chickens, form a promising comparative system for investigating the emergence of novel brain morphologies.

Thyroid hormone manipulation influences development of endothermy and hatching in white leghorn chickens (Gallus gallus)

Chickens experience rapid change in their physiology and metabolism during hatching. We propose that thyroid hormones play a major role in regulating the developmental changes associated with attaining endothermy. To better understand the role thyroid hormones play in hatch timing and development of thermogenic capacity and metabolic rate we manipulated plasma thyroid hormone levels in chicken embryos beginning at 80% development (day 17 of a 21-day incubation) with either a single dose of triiodo-L-thyronine (T3) or the thyroperoxidase inhibitor methimazole (MMI). Manipulation of thyroid hormones altered the timing of hatching, accelerating hatching under hyperthyroid conditions, and prolonging hatching with hypothyroid conditions. Effect sizes comparisons of morphological variables between treatment groups revealed larger heart and body masses in hyperthyroid 1-day post hatch animals. Thyroid hormone manipulation influenced the thermal neutral zone for O2 consumption and body temperature during gradual cooling from 35 to 15 °C of externally pipped embryos and 1-day post hatch chicks. Hyperthyroid EP animals had a wider thermal neutral zone during cooling when compared to control animals. At the temperatures tested, the hypothyroid animals did not exhibit a thermal neutral zone. Similar differences between treatments in the breadth of the thermal neutral zone carried through to 1-day post hatch chickens. These findings suggest that thyroid manipulations influence the timing and development of the animal’s thermogenic response to cooling.

The role of intestinal intraepithelial lymphocytes in resistance against coccidiosis in chickens

Abstract Coccidiosis is a critical enteric disease that costs more than $14.5 billion in annual cost to world poultry industry. It is caused by different Eimeriaspecies that invade and replicate within the intestinal epithelium in a site-specific manner. The Eimeriainfection induces local intestinal damage, reduces feed consumption, feed utilization, and growth performance, and increasing mortality rate. With the recent antibiotic ban including anticoccidial drugs in chicken production, the live vaccination become widely used to control coccidiosis. However, the live vaccines are expensive, require time to circulate in the host to induce a protective immunity, and process a high-risk factor for necrotic enteritis caused by clostridium perfringens. Therefore, there is a high demand for development of safe, protective, and inexpensive vaccines against coccidiosis which require better understanding of host immune responses to Eimeria parasites. The aim of this study is to elucidate the protective role of intestinal intraepithelial lymphocytes (IELs) during the Eimeriainfection. At 3 week of age, SPF white-leghorn chicks were divided into 3 groups. Each group (n=50) was orally inoculated with 20,000 oocytes of Eimeria (E) acervuline or E. maxima, or mock-inoculated with PBS. At 2 day post-infection (dpi), 7 dpi and 14 dpi, the frequency and the number of small intestinal IEL populations were determined by a flow cytometry. Eimeriainfection induced the number of TCRγδ +, TCRβ +, TCR neg, TCRβ +CD4 +, TCRβ +CD4 +CD8α +, TCRβ +CD8αβ +, TCRβ +CD8αα +, and iCD8α IELs compared to the control group at 14 dpi. However, there was no difference among groups at 2 and 7 dpi. More experiments are underway to determine the effector and function of each subset of IELs. Startup funding, The OSU