Search Results (5)

Antibiotic residues in poultry pose health and resistance risks, necessitating breed-specific WDTs. In this study, the residue elimination patterns of seven antibiotics in Taihang chicken tissues under free-range conditions were studied and the appropriate WDT was formulated. A total of 240 healthy Taihang chickens aged 100 days were randomly divided into 8 groups, each comprising 30 chickens. Chickens in groups 1 to 7 were administered oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin, respectively. Regarding the administration method, we adopted the highest dose and maximum course of treatment recommended by the Veterinary Pharmacopoeia of the People’s Republic of China. Group 8 served as the control group. Muscle, sebum, liver, and kidney samples were collected at 4 h, 1 d, 2 d, 3 d, 5 d, 7 d, 10 d, 13 d, and 16 d after drug withdrawal. Our results demonstrated that the drug residues after drug withdrawal gradually decreased with the increase in drug withdrawal days, and the elimination rate in the early stage of drug withdrawal was significantly faster than that in the later stage. At 4 h after drug withdrawal, the drug residues in various tissues reached their highest values. In most cases, the drug concentrations in the kidney and liver were higher than those in the muscles and sebum; however, some drugs also exhibited concentration peaks in the sebum. On the first day of drug withdrawal, the amount of residues in various tissues decreased rapidly. In general, the elimination rate of various drugs in the muscles, liver, and kidneys is faster but slower in the sebum. Based on the WDT calculation software WT1.4, the recommended WDTs for oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin chickens are 4 d, 5 d, 11 d, 8 d, 13 d, 13 d, and 7 d, respectively. These findings support food safety and industry development. Full article

The development and selection of ovarian follicles are essential for continuous egg production in chickens. Non-coding RNAs, particularly circular RNAs (circRNAs), play a critical regulatory role in follicle selection, a process heavily involving granulosa cells (GCs). In this study, we analyzed circRNA expression profiles in small yellow follicles (SYFs) and large yellow follicles (LYFs) of Taihang chickens using RNA sequencing. We identified 14,586 circRNAs, with 57 showing differential expression (DE-circRNAs) between SYFs and LYFs. Functional enrichment analysis revealed that these DE-circRNAs are involved in key biological processes, including signal transduction, cell membrane formation, and nuclear enzymatic regulation. We focused on circGRB14, a circRNA derived from the growth factor receptor-bound protein 14 (GRB14) gene, as a potential regulator of follicle selection. Using qPCR, CCK-8 proliferation assays, and Annexin V/PI apoptosis analysis, we demonstrated that circGRB14 inhibits GC proliferation and promotes apoptosis. In contrast, miR-12264-3p and miR-6660-3p, validated as direct targets of circGRB14 via Dual-Luciferase Reporter assays, exhibited opposing effects by promoting GC proliferation and inhibiting apoptosis. These findings highlight the circGRB14-miR-12264-3p/miR-6660-3p axis as a key regulatory mechanism in GC dynamics during follicle selection. This study provides novel insights into the functional interplay between circRNAs and miRNAs in avian follicle development, offering potential targets for improving egg production in poultry. Full article

The objective of this study was to examine the residue elimination patterns of seven antibiotics in the eggs of Taihang chickens under free-range conditions and develop suitable withdrawal times (WDTs). A total of 240 healthy Taihang chickens, aged 180 days, were randomly divided into eight groups of 30 birds each. The first seven groups were administered oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin, respectively, in accordance with the maximum dosages and longest durations of treatment recommended by the Veterinary Pharmacopoeia of the People’s Republic of China. Group 8 served as the control group, and the test period continued until no drug residue could be detected. The results demonstrate that the residues of oxytetracycline, chlortetracycline, tylosin, tylvalosin, and tiamulin throughout the test period were below the maximum residue limits (MRLs) outlined in GB 31650-2019, “National food safety standard-Maximum residue limits for veterinary drugs in foods”. The egg yolk was identified as the target tissue for estimating the withdrawal time periods (WDTs) of these seven drugs. It was thus concluded that the recommended withdrawal time for tiamulin should be 0 days. However, the WDTs of oxytetracycline, chlortetracycline, tylosin, tylvalosin, were 2.8, 0.3, 2.4, and 7.4, respectively, when the upper limit of the 95% confidence interval was found to be lower than the MRLs. It was thus determined that the recommended WDTs for oxytetracycline, chlortetracycline, tylosin, and tylvalosin should be 3, 1, 3, and 8 days, respectively. In contrast, erythromycin and lincomycin exhibited concentrations below the permitted MRLs on days 7 and 8, respectively. However, the upper limits of the 95% confidence intervals for erythromycin and lincomycin were found to be below the MRLs when the WDTs were 11 and 8.9, respectively. This suggests that the recommended WDTs for these two antibiotics should be 11 days and 9 days. Full article

Improving the efficiency of hens and extending the egg-laying cycle require maintaining high egg production in the later stages. The ovarian follicles, as the primary functional units for ovarian development and oocyte maturation, play a crucial role in regulating the continuous ovulation of hens. The egg production rate of laying hens is mostly affected by proper follicle growth and ovulation in the ovaries. The objective of this study was to identify the key genes and signaling pathways involved in the development of ovarian follicles in Taihang hens through transcriptome screening. In this study, RNA sequencing was used to compare and analyze the transcriptomes of ovarian follicles at four developmental stages: small white follicles (SWF), small yellow follicles (SYF), F5 follicles, and F2 follicles, from two groups: the high continual production group (H-Group) and the low continual production group (L-Group). A total of 24 cDNA libraries were constructed, and significant differential expression of 96, 199, 591, and 314 mRNAs was detected in the SWF, SYF, F5, and F2 follicles of the H and L groups, respectively. Based on the results of GO and KEGG enrichment analyses, each stage of follicle growth possesses distinct molecular genetic features, which have important effects on follicle development and significantly promote the formation of continuous production traits through the biosynthesis of steroid hormones, cytokine–cytokine receptor interaction, and neuroactive ligand–receptor interaction. Additionally, through STEM analysis, we identified 59 DEGs, including ZP4, KCNH1, IGFs, HMGA2, and CDH1, potentially associated with follicular development within four significant modules. This study represents the first transcriptome investigation of follicles in hens with high and low egg-producing characteristics at four crucial developmental stages. These findings provide important molecular evidence for understanding the regulation of follicular development and its variations. Full article

The duodenum is an important digestive organ for poultry and houses a variety of microbes that help chickens to enhance nutrient absorption and improve production. To evaluate the characteristic of gut microbiome, duodenum content samples from 42-week-old native Taihang chickens with high (H) and low (L) egg-yielding were collected for 16S rRNA amplicon sequencing analysis. Consequently, 1,361,341 sequences were clustered into 2055 OTUs, with percentages of affiliation of 96.50 and 57.30% at phylum and genus levels. Firmicutes, Proteobacteria, Cyanobacteria and Bacteroidetes were the dominant phylum, with a lower ratio of Firmicutes/Bacteroidetes in H group than in L group (p < 0.05). At genus level, overrepresentation of Bacteroides, Faecalibacterim, and Enterococcus and underrepresentation of Romboutsia were found in H group. No significant difference in overall diversity of microbiota was observed between two groups. LEFSe analysis revealed Enterococcus was significantly enriched in H group. Importantly, Enterococcus and Lactobacillus were negatively correlated. Functional prediction analysis showed the proportion of microbiota involved in the metabolism process was the highest and enriched in H group. Differences in microbiota composition between the two groups, which may be related to intestinal function difference, also provide promising biomarkers for improving laying hen production. Full article