Prolonged scotophase within a 24 hour light regime improves eggshell quality by enhancing calcium deposition in laying hens

TMT-Based quantitative proteomic analysis reveals age-related changes in eggshell matrix proteins and their correlation with eggshell quality in Xinyang blue-shelled laying hens

The decline in eggshell quality with increasing hen age may be related to changes in ultrastructure and chemical composition, with matrix proteins playing key roles in these changes. However, research on blue-shelled eggs remains limited. This study investigated the effects of hen age (35, 55, 75, and 85 weeks) on the physical, mechanical, and chemical properties of eggshells in the Xinyang blue-shelled laying hens, as well as their ultrastructural and nanostructural characteristics. Subsequently, a comparative proteomic analysis was performed to elucidate the differential protein profiles in eggshells from hens at 35 and 85 weeks of age. Results showed that egg weight, eggshell weight, and eggshell surface area increased with hen age, whereas eggshell stiffness decreased (p < 0.05). As the age advanced, the eggshell organic matter content declined (p < 0.05). The effective layer ratio, mammillae density, as well as the porosity and total pore area in the mammillary layer also decreased with age, whereas the ratio of the mammillary layer increased (p < 0.05). Compared to eggshells collected from 35-week-old hens, those from 85-week-old hens showed increases in egg weight, eggshell weight, surface area, and both the ratio and thickness of the mammillary layer (p < 0.05). However, significant decreases were observed in eggshell stiffness, organic matter content, phosphorus content, effective layer ratio, mammillae density, as well as the porosity and total pore area in the mammillary layer (p < 0.05). Additionally, eggshell stiffness, phosphorus content, and organic matter content were significantly correlated with each other (p < 0.05). Proteomic analysis identified 37 downregulated and 68 upregulated differentially expressed proteins (DEPs, FC > 1.2 or < 0.83, with a p-value < 0.05) in eggshells from 85-week-old hens compared to those from 35-week-old hens. These DEPs are associated with functions such as biomineralization, calcium transport, immunity, and proteases and protease inhibitors. Mantel and Pearson correlations suggest that these functions may be involved in regulating eggshell stiffness, phosphorus content, and organic matter content. Overall, the eggshell stiffness decreased from 35 to 85 weeks of age, which may be attributed to the reductions in eggshell organic matter and phosphorus contents, as well as the deteriorations in eggshell ultrastructure. The proteins associated with biomineralization, calcium transport, immunity, and proteases and protease inhibitors may contribute to these changes.

Responses of laying performance, eggshell quality, calcium, and phosphorus metabolism to feeding patterns and dietary available phosphorus levels in aged laying hens

This study aimed to determine the effects of feeding patterns and dietary available phosphorus levels on laying performance, eggshell quality, calcium, and phosphorus metabolism in aged laying hens. The experiment followed a 3 × 2 factorial arrangement of three feeding patterns (feeding twice a day, 1/2 daily feeding at 8:00, and 1/2 daily feeding at 14:00; disequilibrium feeding twice a day, 1/3 daily feeding at 8:00, and 2/3 daily feeding at 14:00; feeding thrice a day, 1/3 daily feeding at 8:00, 1/3 daily feeding at 14:00, and 1/3 daily feeding at 18:00) and two available phosphorus levels (0.32 %, 0.27 %) was carried out with a total of 528 Hy-Line Brown laying hens aged 62-74 weeks. Each group had 8 replicates of 11 hens. The results revealed that feeding patterns and phosphorus levels significantly interacted with egg production ratios, soft shell and broken egg ratios in weeks 9-12 (P < 0.05). Feeding thrice a day and disequilibrium feeding twice a day significantly improved the equatorial and average eggshell thickness (P < 0.05), and had a trend of increasing eggshell strength at week 12 (P= 0.068). They also significantly increased the effective layer thickness and the calcified layer thickness of the eggshell (P < 0.05). Additionally, feeding thrice a day significantly increased serum calcium content compared with feeding twice a day (P < 0.05), and feeding thrice a day significantly increased the calcium content of the eggshell, mRNA expression level of CaBP-D28k in the uterine compared with the other two feeding patterns (P < 0.05). While disequilibrium feeding twice a day resulted in higher phosphorus content in the excreta compared with the other two feeding patterns (P < 0.05). These results indicated that feeding hens thrice a day with 0.27 % dietary available phosphorus level might improve in laying performance and eggshell quality of aged laying hens.

An innovative protocol to increase egg production of chicken layers

This study investigated the effects of different doses of limestone, light durations, light intensities, and vitamins on both the productive performance and egg quality. The study utilized two rearing houses (control and treatment), each accommodating 75000 Lohmann Brown Classic chicks reared in open-sided rearing cages from one day old until they reached 89 weeks of age. Throughout the laying period, the hens were subjected to a specific light regimen (light = 14 h; dark = 10 h a day). At the end of experiment, the treatment group displayed significant (p<0.05) differences compared to the control group across various parameters. Notably, the treatment group exhibited lower daily feed intake (treatment: 112 g/bird vs control: 115 g/bird), 9.6% higher egg production (treatment: 78.5% vs control: 68.9%), lower body weight (treatment: 2057 g vs control: 2073 g), lower feed conversion ratio (FCR)/egg (treatment: 1.44 vs control: 1.69), higher egg weight (treatment: 69.4 g vs control: 68.5 g), greater egg mass (treatment: 56.14 vs control: 48.76), greater shell thickness (treatment: 3.52 mm vs control: 3.44 mm), and greater shell weight (treatment: 9.3 g vs control: 8.79 g). However, the albumin weight, yolk weight, yolk diameter, shape index, and Haugh units (HU) were not significantly (p˃0.05) affected after 75 weeks of treatment when compared with those of the control group. Therefore, this study is the first of its kind to demonstrate that different ratios of limestone, different durations and intensities of light, and different vitamin supplementation doses in the treatment group (subjected to the novel rearing recommendations described in this study) may yield a profit of 180,541 USD, exceeding the baseline profit of the control group (subjected to conventional rearing methods).

Genetic patterns and genome-wide association analysis of eggshell quality traits of egg-type chicken across an extended laying period

The industry of egg-type chicken has shown a trend of extending the rearing period, with the goal of breeding chicken breeds capable of producing 500 qualified eggs by 700 d of age. However, the rapid decline in eggshell quality during the late laying period is one of the major challenges. In this study, a total of 3,261 Rhode Island Red chickens were used to measure eggshell quality traits including eggshell strength (ESS), eggshell thickness (EST), eggshell color (ESC) and eggshell gloss (ESG) at seven age points ranging from 36 to 90 wk of age. Phenotypic variations increased with the aging process, especially during the late laying period (> 55 wk), and the heritability during this period decreased by 22.7 to 81.4% compared to the initial and peak laying periods. Then we performed genome-wide association study (GWAS) to identify the genomic variants that associated with eggshell quality, with a custom Illumina 50K BeadChip, named PhenoixChip-I. The results indicated that 2 genomic regions on GGA1(23.24-25.15Mb; 175.95-176.05 Mb) were significantly (P < 4.48E-06) or suggestively (P < 8.97E-05) associated with ESS, which can explain 9.59% and 0.48% of the phenotypic variations of ESS46 and ESS36, respectively. Three genes, FRY, PCNX2, and ENSGALG00000052468, were considered to be the candidate genes for ESS. For other traits, the genome-wide suggestive SNPs were identified at each age point, exhibiting a certain trend with aging process. Additionally, SNP enrichment analysis and functional annotation of cross-tissue regulatory elements to ESS36 revealed a high concentration of enhancer elements specific to shell gland and kidney tissues. This study, deepened our knowledge of eggshells and laying a valued scientific foundation for chicken molecular breeding.

Effects of feeding strategies on eggshell quality of laying hens during late laying period

Insufficient calcium supply during the dark period is an important reason for deteriorated eggshell quality in laying hens. In the present study, the feeding time of hens was altered in order to investigate whether the changes in feeding time and feed consumption could influence the laying performance and eggshell quality of hens. A total of 192, 60-wk-old Hy-line Brown hens with similar body weight and laying rate were obtained. The hens were randomly divided into 4 groups and subjected to the following feeding strategies: feeding 3 times a day (control group, CON), or feeding once a day in the morning at 08:00 (MF), in the noon at 12:00 (NF), or in the afternoon at 16:00 (AF), respectively. The feeding strategies had no significant effect (P > 0.05) on laying rate, egg weight, and egg mass. Although the feed intake did not differ among treatments, the time phase of feed consumption was changed. From 15:00 to 21:00 h, hens consumed 49.7%, 42.4%, 49.1%, and 70.8% of daily feed intake in the CON, MF, NF, and AF groups, respectively. Feeding strategy had no detectable influence (P > 0.05) on egg shape index, eggshell strength, and eggshell percentage. Compared to CON, AF hens tended to have a higher eggshell thickness (P = 0.053). In MF and NF treatments, plasma calcium (Ca), phosphorus (P) levels, and alkaline phosphatase (ALP) activity did not differ (P > 0.05) compared with CON. In contrast, AF-hens had lower Ca and P levels, but a higher ALP activity than CON (P < 0.01). The AF hens had higher uterine fluid Ca than MF and NF hens (P < 0.05). Compared to CON, the expression level of CaBP-D28K was increased in the shell gland mucosa of MF-hens. Also, MF-, NF-, and AF-hens had higher Osteopontin (OPN) expression level (P < 0.05), whereas NF had a higher expression of OC-116 (P < 0.01). In conclusion, the results indicated that feeding in the afternoon changed the pattern of feed consumption and exerted a positive influence on eggshell thickness.

Insulin-like growth factor-1 is involved in the deteriorated performance of aged laying hens

The underlying mechanism behind the deteriorated laying performance of aged laying hens remains unclear. In the present study, the laying performance and gene expression along the hypothalamus-pituitary-gonad axis were determined. A total of 300 healthy 90-wk-old ISA hens with similar body weights were classified into three groups according to their laying rate between 90 and 94 wk of age. The experimental groups were the low laying rate (<60%, LLR), high laying rate (>85%, HLR), and intermediate laying rate (60% < laying rate < 85%, MLR) hens. At the end of 94 wk of age, eight hens were randomly selected from each group for tissue collection. The gene expression of hormones and their receptors were determined in the hypothalamus, pituitary, and follicles. The results showed that the serum 17-β-estradiol had no significant difference among the three groups. However, the level of insulin-like growth factor 1 (IGF1) in LLR hens was significantly decreased in the serum, small white follicles (SWF), and dominant follicles (DF, P < 0.05). Within the hypothalamus and small yellow follicles (SYF), the mRNA expression level of estrogen receptor was higher in the MLR group (P < 0.05). Compared with HLR hens, the steroid hormone-synthesis key gene, CYP19A1 was significantly decreased in the SWF of MLR-hens and DF of MLR- and LLR-hens (P < 0.05). The mRNA expression level of IGF1 receptor was higher in the hypothalamus, pituitary, SWF, large white follicles (LWF), SYF, and DF of LLR hens, compared to the HLR hens (P < 0.05). These results suggest that decreased IGF1 in serum and follicles was associated with the decreased egg production of aged laying hens. The present study provides novel insights into the endocrine changes in aged hens having different egg production.

Detecting Ultra- and Circadian Activity Rhythms of Dairy Cows in Automatic Milking Systems Using the Degree of Functional Coupling—A Pilot Study

Ultra- and circadian activity rhythms of animals can provide important insights into animal welfare. The consistency of behavioral patterns is characteristic of healthy organisms, while changes in the regularity of behavioral rhythms may indicate health and stress-related challenges. This pilot study aimed to examine whether dairy cows in free-stall barns with an automatic milking system (AMS) and free cow traffic can develop ultra- and circadian activity rhythms. On 4 dairy farms, pedometers recorded the activity of 10 cows each over 28 days. Based on time series calculation, the Degree of Functional Coupling (DFC) was used to determine the cows' activity rhythms. The DFC identified significant rhythmic patterns in sliding 7-day periods and indicated the percentage of activity (0–100%) that was synchronized with the 24-h day-night rhythm. As light is the main factor influencing the sleep-wake cycle of organisms, light intensity was recorded in the AMS, at the feed alley and in the barn of each farm. In addition, feeding and milking management were considered as part of the environmental context. Saliva samples of each cow were taken every 3 h for 1 day to determine the melatonin concentration. The DFC approach was successfully used to detect activity rhythms of dairy cows in commercial housing systems. However, large inter- and intra-individual variations were observed. Due to a high frequency of 0 and 100%, a median split was used to dichotomize into “low” (&lt;72.34%) and “high” (≥72.34%) DFC. Forty percent of the sliding 7-day periods corresponded to a low DFC and 50% to a high DFC. No DFC could be calculated for 10% of the periods, as the cows' activity was not synchronized to 24 h. A generalized linear mixed-effects model revealed that the DFC levels were positively associated with a longer milking interval and a higher amount of daytime activity and negatively associated with higher number of lactations. The DFC is a novel approach to animal behavior monitoring. Due to its automation capability, it represents a promising tool in its further development for the purpose of longitudinal monitoring of animal welfare.