Age-related changes in eggshell physical properties, ultrastructure, calcium metabolism-related serum indices, and gene expression in eggshell gland during eggshell formation in commercial laying ducks

Supplemental effect of Pediococcus acidilactici CNCM I-4622 probiotic on the laying characteristics and calcium and phosphorus metabolism in laying hens

The close link between intestinal microbiota and bone health ('gut-bone' axis) has recently been revealed: the modulation of the amount and nature of bacteria present in the intestinal tract has an impact on bone health and calcium (Ca) metabolism. Probiotics are known to favorably impact the intestinal microbiota. The objective of this study was to investigate the effect of Pediococcus acidilactici CNCM I-4622 (PA) on laying performance, egg/eggshell quality, Ca metabolism and bone mineralization and resistance in relatively old layers (50 wks old at the beginning of the experiment) during 14 weeks. 480 Hy Line brown layers were divided into 2 groups (CON and PA: 3 layers/rep, 80 rep/group) and fed with a diet formulated to be suboptimal in calcium (Ca) and phosphorus (P) (- 10% of the requirements). The total egg weight was improved by 1.1% overall with PA, related to an improvement of the weight of marketable eggs (+ 0.9%). PA induced a decreased % of downgraded eggs, mainly broken eggs (- 0.4 pts) and FCR improvement (- 0.8% for all eggs, - 0.9% for marketable eggs). PA also led to higher Haugh units (HU: + 7.4%). PA tended to decrease crypt depth after the 14 weeks of supplementation period in the jejunum (- 25.2%) and ileum (- 17.6%). As a consequence, the VH/CD ratio appeared increased by PA at the end of the trial in the jejunum (+ 63.0%) and ileum (+ 48.0%). Ca and P retention were increased by 4 pts following PA supplementation, translating into increased bone hardness (+ 19%), bone cohesiveness (+ 43%) and bone Ca & P (+ 1 pt) for PA-supplemented layers. Blood Ca and P were respectively improved by 5% and 12% with PA. In addition, blood calcitriol and osteocalcin concentrations were respectively improved by + 83% and + 3% in PA group at the end of the trial, compared to CON group. There was no difference between the 2 groups for ALP (alkaline phosphatase) and PTH (parathyroid hormone). PA significantly decreased the expression of the following genes: occludin in the small intestine, calbindin 1 in the ovarian tissue and actin B in the bone. PA therefore improved zootechnical performance of these relatively old layers, and egg quality. The parallel increase in Ca and P in the blood and in the bone following PA supplementation suggests an improvement of the mineral supply for eggshell formation without impacting bone integrity, and even increasing bone resistance.

The ionome and proteome landscape of aging in laying hens and relation to egg white quality

The ionome is essential for maintaining body function and health status by participating in diverse key biological processes. Nevertheless, the distribution and utilization of ionome among different organs and how aging impacts the ionome leading to a decline in egg white quality remain unknown. Thus, we used inductively coupled plasma mass spectrometry (ICP-MS) to analyze 35 elements and their isotopic contents in eight organs of laying hens at 35, 72, and 100 weeks. Moreover, the magnum proteome, amino acids in egg white, and egg white quality were analyzed in laying hens at three different ages using 4D proteomics techniques, an amino acid analyzer, and an egg quality analyzer. Across the organs, we identified varying distribution patterns among macroelements (Mg24, Ca43/44, K39, and P31), transition metals (Zn64/66, Cu63/65, Fe56/57, and Mn55), and toxic elements (Pb208, Ba137, and Sr86). We observed an organ-specific aging pattern characterized by the accumulation of toxic elements (Pb208, Ba137, and Sr86) and calcification in the small intestine. Additionally, a decrease in the utilization of essential trace elements selenium (Se78/82) and manganese (Mn55) was noted in the oviduct. By analyzing ionome in tandem with egg quality, egg white amino acids, and proteome, we unveiled that the reduction of selenium and manganese concentrations in the magnum during the aging process affected amino acid metabolism, particularly tryptophan metabolism, thereby inhibiting the amino acid synthesis in the magnum. Furthermore, it accelerated the senescence of magnum cells through necroptosis activation, leading to a decline in the albumen secretion function of the magnum and subsequently reducing egg white quality. Overall, this study provides insights into the evolution of 35 elements and their isotopes across 8 organs of laying hens with age. It also reveals the elemental composition, interactions, and utilization patterns of these organs, as well as their correlation with egg white quality. The present study highlights the significance of ionome and offers a comprehensive perspective on the selection of ionome for regulating the aging of laying hens.

A Method to Reduce the Occurrence of Egg Translucency and Its Effect on Bacterial Invasion

Translucent egg consumption is low due to consumer acceptance and quality concerns, which is a problem that egg producers need to address. This study was performed to evaluate the reasons for the high occurrence of egg translucency in summer, as well as whether the addition of mono-dicalcium phosphate (MDCP) to the diet can relieve eggshell translucency and whether eggshell translucency is associated with the risk of bacterial invasion. A total of 72 laying hens that were 36 weeks old were randomly divided into control (CON) and MDCP groups and fed in the same environment. Results showed that the number of translucent eggs increases in July and August as the temperature and humidity increase. Compared with the CON group, in July, August, and October, the translucent egg grade (TEG) of the MDCP group was lower than that of the CON group (p < 0.05). TEG was correlated with mastoid space height (MSH), width (MSW), and area (MSA) (correlation coefficients 0.63, 0.59, and 0.68, respectively, p ≤ 0.05). There was no significant difference in the invasion rate of E. coli between translucent and non-translucent egg groups (47.2% vs. 39.33%), and translucent area and non-translucent area (13.49% vs. 15.08%). In conclusion, our results show that dietary MDCP may alleviate eggshell translucency and that eggshell translucency would not increase the probability of E. coli cross-shell penetration rate.

Production performance, egg quality, and uterine gene expression for layers as affected by N-Carbamylglutamate supplementation

Introduction

Supplementation of exogenous additives is a strategy to improve laying performance of layers by regulating uterine function. N-Carbamylglutamate (NCG) as an activator for endogenous arginine synthesis has the potential to regulate the laying performance of layers, but its effects have not been fully understood.

Methods

This study investigated the effects of dietary supplementation of NCG on production performance, egg quality, and uterine gene expression in layers. A total of 360 45-week-old layers with a genetic line of Jinghong No. 1 were used in this study. The experimental period was 14 weeks. All birds were divided into 4 treatments with 6 replicates per treatment and 15 birds per replicate. Dietary treatments were based on a basal diet and supplemented with 0, 0.08, 0.12, or 0.16% NCG to form C, N1, N2, and N3 groups.

Results and discussion

We found that layers in group N1 had higher egg production rate than those in group C. Egg weight was significantly reduced, while eggshell thickness was significantly improved, by treatment. However, the albumen height and Haugh unit were the lowest in group N3. Based on the above results, groups C and N1 were selected for further transcriptomics analysis of uterine tissue by RNA-seq. More than 7.4 Gb clean reads and 19,882 tentative genes were obtained using the Gallus gallus genome as a reference. Transcriptomics analysis in uterus tissue revealed that 95 differentially expressed genes (DEGs) were upregulated and 127 DEGs were downregulated. Functional annotation and pathway enrichment analysis showed that DEGs in uterine tissue were mainly enriched in glutathione metabolism, cholesterol metabolism, and glycerolipid metabolism, etc. Vitamin A metabolism-related gene, RBP1, nutrient transport-related gene, ALB, protein synthesis-related gene, METTL21C, and calcium transport-related gene, RYR2, CACNB2, RAMP3, and STAC, were significantly regulated by 0.08% NCG supplementation. Therefore, we concluded that NCG supplementation at a dose of 0.08% improved production performance and egg quality of layers by regulating uterus function.

The age of the geese from the parent flock and the laying period affect the features of the eggs

The study aimed to assess the goose hatching egg features in four reproductive seasons from 3 stages of laying. Three hundred sixty eggs were used in the study from geese in the first, second, third, and fourth laying season. From each group, 90 eggs were analyzed (30 eggs from the beginning, the peak, and the end of the laying cycle). The structure of the egg and morphological and physical features of the yolk, albumen, and eggshell were analyzed. It was shown that the weight and structure of eggs increased, but the shape index was lower in 2-yr-old geese, as well Haugh's units decreased. The yolk share was lower in the first year, but albumen and eggshell were higher than in other groups. The eggshell whiteness was higher in the first year than in the second, and third. The pores’ quantity was higher in the first year in the blunt and equatorial parts, but the total number in the egg was the highest in the fourth year. The yolk, albumen, and eggshell' density increased with the age. Changes in laying periods were inversely proportional to the changes shown depending on the layers’ age. Geese's age and laying period impact the eggs’ features. Based on the egg quality features, the incubation conditions could be adapted, as well as it can be treated as an indicator of the effectiveness of hatching and goslings quality. Research has shown that the biological value of hatching eggs changes with the age of the geese and the laying period.