Polymorphisms in the ovoinhibitor gene (OIH) and their association with egg quality of Xinhua E-strain chickens

Macleaya cordata extract improves egg quality by altering gut health and microbiota in laying hens

This study investigated the effect of Macleaya cordata extract (MCE) on the performance, gut health, and microbiota of laying hens. A total of 192 thirty-wk-old Hyline brown laying hens were randomly divided into 4 treatment groups. The CON group received a basal diet, while the low (MCE250), medium (MCE350), and high (MCE450) dose groups were supplemented with 250, 350, and 450 mg/kg MCE, respectively. The egg weight and Haugh unit demonstrated a linear and quadratic increase with the MCE dose during the initial 4-wk period of the experiment (P < 0.05). Furthermore, the dietary supplementation of MCE led to a significant enhancement in eggshell thickness and Haugh unit at wk 8 and the data showed a statistically significant linear and quadratic increase (P < 0.05). Serum cytokine assay showed that dietary supplementation of MCE led to linear and quadratic increases in IL-4 and IL-10 level (P < 0.05). Dietary supplementation of 350 and 450 mg/kg MCE was observed to result in linear and quadratic increase in serum lysozyme levels (P < 0.05). The addition of MCE to the diet resulted in a linear and quadratic increase in the levels of sIgA in the jejunum and ileum (P < 0.05). In terms of gene expression, the addition of MCE to the diet resulted in linear and quadratic increases in the expression of IL-10, IgA, Serpinb14, Serpinb14B, and OIH (P < 0.05). The expression of jejunal genes pIgR and IL-4 was observed to increase in a linear and quadratic manner, respectively, following the dietary addition of 350 mg/kg MCE and IL-1β decreased in a linear manner (P < 0.05). Moreover, these favorable effects were maximized at medium dosage (350 mg/kg) of MCE addition, and intestinal microbial composition in the control and MCE350 groups was assessed. 350 mg/kg MCE increased the relative abundance of Bryobacter and Parasutterella and decreased the relative abundance of Erysipelatoclostridium in the cecum (P < 0.05). Spearman correlation analysis revealed that Bryobacter, Parasutterella, Skermanella, and Erysipelatoclostridium were associated with nonspecific immune functions (P < 0.05). In conclusion, 350 mg/kg MCE supplementation elevated the immune response, and upregulated the expression of genes related to protein production in eggs, thereby improving egg quality. These effects may be associated with changes in the microbiota, specifically Bryobacter, Parasutterella, and Erysipelatoclostridium.

Endocrine and genetic factors affecting egg laying performance in chickens: a review

1. Egg-laying performance reflects the overall reproductive performance of breeding hens. The genetic traits for egg-laying performance have low or medium heritability, and, depending on the period involved, usually ranges from 0.16 to 0.64. Egg-laying in chickens is regulated by a combination of environmental, endocrine and genetic factors. 2. The main endocrine factors that regulate egg-laying are gonadotropin-releasing hormone (GnRH), prolactin (PRL), follicle-stimulating hormone (FSH) and luteinising hormone (LH). 3. In the last three decades, many studies have explored this aspect at a molecular genetic level. Recent studies identified 31 reproductive hormone-based candidate genes that were significantly associated with egg-laying performance. With the development of genome-sequencing technology, 64 new candidate genes and 108 single nucleotide polymorphisms (SNPs) related to egg-laying performance have been found using genome-wide association studies (GWAS), providing novel insights into the molecular genetic mechanisms governing egg production. At the same time, microRNAs that regulate genes responsible for egg-laying in chickens were reviewed. 4. Research on endocrinological and genetic factors affecting egg-laying performance will greatly improve the reproductive performance of chickens and promote the protection, development, and utilisation of poultry. This review summarises studies on the endocrine and genetic factors of egg-laying performance in chickens from 1972 to 2019.