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Campylobacter hepaticus, the causative agent of Spotty Liver Disease (SLD) is an important disease in cage-free egg producing chickens causing mortality and production drops. C. hepaticus is a slow growing Campylobacter easily overgrown by fecal bacteria. It is currently only reliably isolatable from bile samples. A selective media for isolation from feces or environment would assist diagnosis and impact assessment. Growth of five Australian C. hepaticus isolates was studied using Horse blood agar (HBA), sheep blood agar (SBA), Bolton, Preston and Brain Heart Infusion (BHI) base media. Blood and/or bile were added to Bolton, Preston and BHI medias. C. jejuni was used as a positive control. Plates were incubated in duplicate under microaerophilic conditions at 42°C for 10 days and examined at days 3–5 and 7–10 of incubation. Each isolate was examined for sensitivity to 14 antimicrobials using HBA sensitivity plates. Growth was inhibited by BHI and by added bile, while blood improved growth. Further replicates using SBA, HBA, Bolton and Preston media showed best growth on Bolton agar with blood. All five C. hepaticus isolates were resistant to trimethoprim and vancomycin, while four were also resistant to rifampicin and bacitracin. Media based upon Bolton plus blood supplemented with vancomycin and trimethoprim might be used as the most appropriate media for selective growth of C. hepaticus. The addition of bile to media for C. hepaticus isolation and growth will inhibit growth and is not advised. [ABSTRACT FROM AUTHOR]

The genetic complexity of polygenic traits represents a captivating and intricate facet of biological inheritance. Unlike Mendelian traits controlled by a single gene, polygenic traits are influenced by multiple genetic loci, each exerting a modest effect on the trait. This cumulative impact of numerous genes, interactions among them, environmental factors, and epigenetic modifications results in a multifaceted architecture of genetic contributions to complex traits. Given the well-characterized genome, diverse traits, and range of genetic resources, chicken (Gallus gallus) was employed as a model organism to dissect the intricate genetic makeup of a previously identified major Quantitative Trait Loci (QTL) for body weight on chromosome 1. A multigenerational advanced intercross line (AIL) of 3215 chickens whose genomes had been sequenced to an average of 0.4x was analyzed using genome-wide association study (GWAS) and variance-heterogeneity GWAS (vGWAS) to identify markers associated with 8-week body weight. Additionally, epistatic interactions were studied using the natural and orthogonal interaction (NOIA) model. Six genetic modules, two from GWAS and four from vGWAS, were strongly associated with the studied trait. We found evidence of both additive- and non-additive interactions between these modules and constructed a putative local epistasis network for the region. Our screens for functional alleles revealed a missense variant in the gene ribonuclease H2 subunit B (RNASEH2B), which has previously been associated with growth-related traits in chickens and Darwin's finches. In addition, one of the most strongly associated SNPs identified is located in a non-coding region upstream of the long non-coding RNA, ENSGALG00000053256, previously suggested as a candidate gene for regulating chicken body weight. By studying large numbers of individuals from a family material using approaches to capture both additive and non-additive effects, this study advances our understanding of genetic complexities in a highly polygenic trait and has practical implications for poultry breeding and agriculture. [ABSTRACT FROM AUTHOR]

Marek's disease (MD) is an important neoplastic disease caused by serotype 1 Marek's disease virus (MDV-1), which results in severe economic losses worldwide. Despite vaccination practices that have controlled the MD epidemic, current increasing MD-suspected cases indicate the persistent viral infections circulating among vaccinated chicken farms in many countries. However, the lack of available information about phylogeny and molecular characterization of circulating MDV-1 field strains in Taiwan reveals a potential risk in MD outbreaks. This study investigated the genetic characteristics of 18 MDV-1 strains obtained from 17 vaccinated chicken flocks in Taiwan between 2018 and 2020. Based on the sequences of the meq oncogene, the phylogenetic analysis demonstrated that the circulating Taiwanese MDV-1 field strains were predominantly in a single cluster that showed high similarity with strains from countries of the East Asian region. Because the strains were obtained from CVI988/Rispens vaccinated chicken flocks and the molecular characteristics of the Meq oncoprotein showed features like vvMDV and vv+MDV strains, the circulating Taiwanese MDV-1 field strains may have higher virulence compared with vvMDV pathotype. In conclusion, the data presented demonstrates the circulation of hypervirulent MDV-1 strains in Taiwan and highlights the importance of routine surveillance and precaution strategies in response to the emergence of enhanced virulent MDV-1. [ABSTRACT FROM AUTHOR]

In commercial laying hens, keel bone damage (KBD) is a severe health and welfare problem leading to pain, reduced mobility and decreased laying performance. Flocks of all production systems and hybrid lines can be affected. KBD is a multifactorial welfare issue and, among other factors, associated with a high laying performance which negatively affects the calcium deposit in the medullary bones. Therefore, mature hens of local breeds with much lower egg production than commercial hybrids may be expected to show less or even no keel bone damage. This study evaluates (i) the prevalence of KBD in local breeds, (ii) the difference in type and level of damages, and (iii) if roosters and pullets are also affected. In total, we palpated 343 mature hens, 40 pullets, and 18 roosters of 13 different local breeds and one commercial hybrid. The animals were kept on eight different farms in free-range or floor-housing systems. Our results showed that on average 44.2% of mature hens per local breed were affected by KBD (range: 11.1%-84.7%). We found deviation of less than 1 cm in 26.9%, deviations of more than 1 cm in 6.4% and palpable fractures in 23.8% of the mature hens of local breeds. The tip was damaged in 23.6% of the mature hens. Also, pullets and roosters were affected by KBD. Finally, we found that KBD also occurs in local breeds. Therefore, we conclude that even the low laying performance of local breeds does not prevent them from the occurrence of KBD.KBD in local breeds may rather be associated with genetics (breed) as well as management and housing. Thus, breeders of local breeds should include bone health as a selection trait. Owners of local breeds should also pay attention to the condition of the keel and ought to be trained about preventive measures. [ABSTRACT FROM AUTHOR]