Project description:Odour is one of the main environmental concerns in the laying hen industry and may also influence animal health and production performance. Previous studies showed that odours from the laying hen body are primarily produced from the microbial fermentation (breakdown) of organic materials in the caecum, and different laying hen species may have different odour production potentials. This study was conducted to evaluate the emissions of two primary odorous gases, ammonia (NH<sub>3</sub>) and hydrogen sulphide (H<sub>2</sub>S), from six different laying hen species (Hyline, Lohmann, Nongda, Jingfen, Xinghua and Zhusi). An in vitro fermentation technique was adopted in this study, which has been reported to be an appropriate method for simulating gas production from the microbial fermentation of organic materials in the caecum. The results of this study show that Jingfen produced the greatest volume of gas after 12 h of fermentation (<i>p</i> < 0.05). Hyline had the highest, while Lohmann had the lowest, total NH<sub>3</sub> emissions (<i>p</i> < 0.05). The total H<sub>2</sub>S emissions of Zhusi and Hyline were higher than those of Lohmann, Jingfen and Xinghua (<i>p</i> < 0.05), while Xinghua exhibited the lowest total H<sub>2</sub>S emissions (<i>p</i> < 0.05). Of the six laying hen species, Xinghua was identified as the best species because it produced the lowest total amount of NH<sub>3</sub> + H<sub>2</sub>S (39.94 µg). The results for the biochemical indicators showed that the concentration of volatile fatty acids (VFAs) from Zhusi was higher than that for the other five species, while the pH in Zhusi was lower (<i>p</i> < 0.01), and the concentrations of ammonium nitrogen (NH<sup>4+</sup>), uric acid and urea in Xinghua were lower than those in the other species (<i>p</i> < 0.01). Hyline had the highest change in SO<sub>4</sub><sup>2-</sup> concentration during the fermentation processes (<i>p</i> < 0.05). In addition, the results of the correlation analysis suggested that NH<sub>3</sub> emission is positively related to urease activities but is not significantly related to the ureC gene number. Furthermore, H<sub>2</sub>S emission was observed to be significantly related to the reduction of SO<sub>4</sub><sup>2-</sup> but showed no connection with the aprA gene number. Overall, our findings provide a reference for future feeding programmes attempting to reduce odour pollution in the laying hen industry.
Project description:The objective of this study was to identify candidate genes associated with sexual maturity and ovary development of chicken. Gene expression profiling sequencing analysis was employed using pre-laying (P-F-O1, L-F-O1) and laying ovaries (P-F-O2, L-F-O2) from two sub-breeds of Ningdu Yellow chicken. RNA-seq data and qPCR showed that HEP21 significantly differential expressed between the pre-pubertal ovary and pubertal ovary. A total of 23 variations were detected on HEP21. Association analysis between SNP in HEP21 and chicken reproductive traits showed that rs315156783 was significantly related to chicken comb height at 84 and 91 days. Overall design: Examination of mRNA profiles in 32-day-old early sexual maturity pre-laying-hen (P-F-O1), 103-day-old early sexual maturity laying-hen (P-F-O2), 32-day-old late sexual maturity pre-laying-hen (L-F-O1), and 153-day-old late sexual maturity pre-laying-hen (L-F-O2).