The objective of this study was to evaluate the effects of storage temperature and time on the quality parameters of eggs from laying hens at peak production. A total of 576 eggs were obtained from Lohmann Light-Brown hens, which were collected 3 times when the hens were 26, 27, and 28 weeks old. The fresh eggs were collected and measured within 2 h of being laid. Samples of 48 eggs each were stored in chambers for 2, 5, or 10 d inside a refrigerator (5°C), at room temperature (21°C), and at a high temperature (29°C). As the storage temperature and time increased, egg weight, percentage of albumen, Haugh unit (HU), and yolk color significantly (p<0.001) decreased. In addition, egg shell weight, shell percentage, and albumen weight significantly (p<0.001) decreased with storage time. Yolk weight, yolk percentage, and albumen pH significantly (p<0.001) increased with increasing storage temperature, and yolk pH significantly (p<0.001) increased with increasing storage time. When the storage temperature was increased to 29°C, egg weight loss dramatically increased from 1.74 to 3.67% at 5 and 10 d of storage time, respectively. With the exception of the 5°C storage temperature, HU dramatically decreased according to storage time and temperature, decreasing from 91.3 to 72.63 at 21°C and from 87.62 to 60.92 at 29°C during 10 d of storage; however, this decline was not found at 5°C. A rapid increase in albumen alkalinity was observed even after just 2 d of storage regardless of the storage temperature. Interactions between storage time and temperature were significant (p<0.001) with respect to egg weight loss, egg shell weight and percentage, albumen weight and percentage, yolk weight and percentage, albumen and yolk pH, HU, and yolk color. The results of the current study indicated that eggs from laying hens at peak production had significant deterioration of internal quality with increasing storage temperature and time. The results suggest that egg weight loss, albumen pH, and HU are parameters that are greatly influenced by the storage temperature and time of eggs from hens at peak laying.

This study evaluated the changes in eggshell mechanical properties, ultrastructure, calcium metabolism-related serum indices, and gene expression in eggshell gland during eggshell formation between laying ducks in the peak (young duck) and late phase (aged duck) of production. A total of 84 healthy young (31 wk of age) and 84 healthy aged (65 wk of age) Longyan laying ducks were each divided into 6 replicates of 14 birds, and caged individually. All the ducks were fed in one house with the same corn-soybean meal-based diet for 5 wk. The eggshell mechanical properties (shell proportion, thickness, breaking strength, and fracture toughness) and chemical components (matrix proteins, calcium, phosphorus, and magnesium) decreased in aged laying ducks ( P < 0.05). Shell structural indices: total thickness, effective thickness and its proportion decreased, whereas mammillary knob width and its proportion increased ( P < 0.05). The regulation values of early fusion, cuffing, caps, and total score of mammillary knobs were higher in aged laying ducks relative to the young ducks ( P < 0.05). During the initial, growth and terminal stages of eggshell formation, shell thickness and breaking strength (terminal), shell weight, and its proportion (terminal) decreased in aged laying ducks ( P < 0.05). Ultrastructural changes during shell formation indicated that the mammillary-knob density and effective thickness decreased ( P < 0.05). Decreases occurred in serum content of phosphorus (growth), and estradiol and calcium contents (terminal) ( P < 0.05). Relative expression of Ca 2+ transporter and HCO 3 − exchanger, and matrix proteins genes decreased in aged laying ducks ( P < 0.05) at all stages of eggshell formation. Collectively, the decreased incidence of early fusion and caps, increased thickness and width of mammillary knobs, and decreased effective thickness are the crucial differences leading to the compromised mechanical properties of eggshell in the late laying period. A disturbed regulation of calcium metabolism and uterine expression of ion transporters, especially for HCO 3 − exchange of aged laying ducks likely contribute to age-induced ultrastructural deterioration of the eggshell.

The present study was conducted to investigate the effects of heat stress on microbial community in the duodenum of yellow-feather broiler chickens based on 16S rRNA sequencing. A total of 40 female Chinese indigenous yellow-feather broilers (56-day-old, average initial body weight of 840.75 ± 20.79 g) were randomly allocated to two groups, including the normal treatment group (NT group, 21.3 ± 1.2 C, 24 h/day) and the heat stress group (HS group, 32.5 ± 1.4 C, 10 h/day), and the relative humidity (RH) of both two groups was maintained at 65 ± 5%. The experiment conforms to a completely randomised trial design. Broilers in both of two groups were fed basal diet, each group consisted of five replicates, and four broilers in each replicate. The feeding trail lasted 4 weeks. The results showed that although the broilers in the HS group had lower abundance-based coverage estimators (ACE) and Chao1 richness estimator (Chao1) index of duodenal microbial, there were no significant differences in duodenal microbial alpha diversity index between NT and HS groups, including ACE, Chao1, Shannon and Simpson index (p > .05). Regarding the microbial composition and abundance, at the phylum level, heat stress exposure significantly decreased the relative abundance of Bacteroidetes in duodenum compared with NT group (p < .05). At the genus level, compared with the NT group, heat stress exposure significantly reduced the relative abundance of Cupriavidus, Leptothrix, Janthinobacterium, Pseudomonas, Stenotrophomonas, Desulfovibrio, Oscillospira and Dorea in the duodenum (p < .05). In conclusion, heat stress affected the duodenal microbial community in indigenous yellow-feather broilers. HIGHLIGHTSHeat stress had adverse effects on duodenal microbial composition of Chinese indigenous yellow-feather broilers. Strategies that improve the duodenal microbial balance may promote the gut health and reduce the economic losses caused by heat stress in broiler production.

Objectives:The broiler chickens are susceptible to heat stress (HS), including the indigenous broilers raised in tropical and subtropical regions. HS caused intestinal dysfunction and disrupted the gut microbiota. However, the researches about the effects of HS on ileal microbiome of indigenous broilers are limited. Therefore, this experiment used 16S rRNA sequencing to analyse the ileal microbial community in indigenous yellow-feather broilers under HS. Material and methods:The single factor completely random design was used in the present study, and forty 8-week-old Chinese indigenous yellow-feather broilers (Huaixiang chickens) were randomly divided into two treatments: normal temperature (NT) group and HS group. There are five replications with four broilers per replicate in each group. The broilers in NT group were raised at 21.3 ± 1.2 • C during the whole experimental period, the broilers in HS group were exposed to 32.5 ± 1.4 • C for 8 h/day from 9:00 am to 17:00 pm and the temperature of rest time is consistent with NT group.The experiment lasted for 4 weeks. Results:The results showed that HS exposure had no significant effects on the alpha diversity index of ileal microflora of broilers, including the Shannon, Simpson, Chao1 and ACE indexes (p > 0.05). At the genus level, HS significantly reduced the relative abundance of Campylobacter (p < 0.05), and increased the abundance of Delftia (p < 0.05). In addition, prediction of microbial community function indicated that HS significantly enhanced the abundance of the microflora related to lipid metabolism, carbohydrate metabolism and xenobiotics biodegradation and metabolism and reduced the abundance of the microflora related to nucleotide metabolism and amino acid metabolism. Conclusions:Taken together, the present study revealed that chronic HS (4 weeks) exposure changes the abundance of the ileal microflora of broilers. These findingsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.