Application of RNA-sequencing to identify biomarkers in broiler chickens prophylactic administered with antimicrobial agents

Omics technologies in poultry health and productivity - part 2: future applications in the poultry industry

The increasing global demand for poultry products, together with the growing consumer concerns related to bird health and welfare, pose a significant challenge to the poultry industry. Therefore, the poultry industry is increasingly implementing novel technologies to optimize and enhance bird welfare and productivity. This second part of a bipartite review on omics technologies in poultry health and productivity highlights the implementation of specific diagnostic biomarkers based on omics-research in the poultry industry, as well as the potential integration of multi-omics in future poultry production. A general discussion of the use of multiple omics technologies in poultry research is provided in part 1. To date, approaches focusing on one or more omics type are widely used in poultry research, but the implementation of these omics techniques in poultry production is not expected in the near future. However, great potential lays in the development of diagnostic tests based on disease- or gut health-specific biomarkers, which are identified through omics research. As the cost of omics technologies is rapidly decreasing, implementation of multi-omics measurements in routine poultry monitoring systems might be feasible in the more distant future. Therefore, the opportunities, challenges and requirements to enable the integration of multi-omics-based monitoring of bird health and productivity in future poultry production are discussed.

Assessment of Antimicrobial Effects on Broiler Gut Barrier Through Histopathology and Immunohistochemistry of Tight-Junction Proteins

In recent years, antimicrobial (AM) use in poultry farming has been attracting attention worldwide mainly due to AM resistance spreading. The role of AM prophylaxis in the modulation of gut microbiota, as well as of gut health, is still not clearly understood. Therefore, this study aimed to investigate the role of different prophylaxis protocols in the modulation of the gut barrier in broilers by applying a histopathological approach. Intestinal tissue samples were collected from a total of 240 male broilers (Ross 306), reared and treated with different AM protocols. Haematoxylin and Eosin (HE) staining and a multiple scoring system were used to evaluate the presence of lesions in ileum, cecum and colon of treated broilers. Moreover, immunohistochemistry (IHC) was performed to assess the expression of claudin-3 and ZO-1 proteins in intestinal tissues. The application of a semi-quantitative scoring system was used in IHC stained samples. HE results revealed that intestinal tissues were mainly characterized by epithelial detachment and fusion of the intestinal villi, but also by the presence of lymphocytic infiltrate in the mucosa and submucosa of AM-treated broilers. However, the IHC approach for the evaluation of claudin-3 and ZO-1 proteins showed that their expression was not affected by the different AM treatments. Nevertheless, the presence of intestinal lesions highlighted by histopathology suggests that AM treatments could harm the gut health of broilers, inducing an inflammatory response and consequent epithelial lesions. In order to clarify the role of AM treatments in the modulation of gut barrier in broilers, further studies are needed.

Feather pulp: a novel substrate useful for proton nuclear magnetic resonance spectroscopy metabolomics and biomarker discovery

Noninvasive biomarkers of stress that are predictive of poultry health are needed. Feather pulp is highly vascularized and represents a potential source of biomarkers that has not been extensively explored. We investigated the feasibility and use of feather pulp for novel biomarker discovery using ¹H-Nuclear Magnetic Resonance Spectroscopy (NMR)-based metabolomics. To this end, high quality NMR metabolomic spectra were obtained from chicken feather pulp extracted using either ultrafiltration (UF) or Bligh-Dyer methanol-chloroform (BD) methods. In total, 121 and 160 metabolites were identified using the UF and BD extraction methods, respectively, with 71 of these common to both methods. The metabolome of feather pulp differed in broiler breeders that were 1-, 23-, and 45-wk-of-age. Moreover, feather pulp was more difficult to obtain from older birds, indicating that age must be considered when targeting feather pulp as a source of biomarkers. The metabolomic profile of feather pulp obtained from 12-day-old broilers administered corticosterone differed from control birds, indicating that the metabolome of feather pulp was sensitive to induced physiological stress. A comparative examination of feather pulp and serum in broilers revealed that the feather pulp metabolome differed from that of serum but provided more information. The study findings show that metabolite biomarkers in chicken feather pulp may allow producers to effectively monitor stress, and to objectively develop and evaluate on-farm mitigations, including practices that reduce stress and enhance bird health.

16S rRNA Sequencing Analysis of the Gut Microbiota in Broiler Chickens Prophylactically Administered with Antimicrobial Agents

In poultry production, gut microbiota (GM) plays a pivotal role and influences different host functions related to the efficiency of production performances. Antimicrobial (AM) use is one of the main factors affecting GM composition and functions. Although several studies have focused their attention on the role of AMs as growth promoters in the modulation of GM in broilers, the consequences of higher AM concentrations administered during prophylactic treatments need to be better elucidated. For this purpose, 16S rRNA gene sequencing was performed to evaluate the impact of different prophylactic AM protocols on the composition and diversity of the broiler GM. Diversity analysis has shown that AM treatment significantly affects alpha diversity in ileum and beta diversity in both ileum and caecum. In ileal samples, the Enterobacteriaceae family has been shown to be particularly affected by AM treatments. AMs have been demonstrated to affect GM composition in broiler. These findings indicate that withdrawal periods were not enough for the restoral of the original GM. Further studies are needed for a better elucidation of the negative effects caused by an altered GM in broilers.