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Dietary zinc supplementation affects eggshell quality and ultrastructure in commercial laying ducks by influencing calcium metabolism.

ABSTRACT: This study evaluated dietary Zn supplementation on productive performance, eggshell quality and ultrastructure, and calcium metabolism during eggshell formation in laying ducks. A total of 360 Longyan laying ducks (45-wk) were randomly divided into 5 treatment groups with 6 replicates of 12 birds each and fed for 20 wk. The 6 treatments fed the basal diet supplemented with 0 (control), 20, 40, 80, or 160 mg Zn/kg (ZnSO₄·H₂O). Dietary supplemental level at 80 mg/kg increased egg production (4.3%) and mass (5.7%), and decreased FCR (2.9%) compared to the basal diet, and these indices increased quadratically with increasing Zn supplemental levels (P < 0.05). The shell breaking strength (15.8%) and fracture toughness (10.6%) were higher with the supplementation of Zn at 80 mg/kg than the basal diet, and increased quadratically with Zn supplementation (P < 0.05). Dietary supplementation of Zn at 80 mg/kg improved shell ultrastructure by increasing total (9.0%) and effective thickness (14.2%) and decreasing mammillary thickness (12.0%), and their responses were quadratic with increasing Zn levels (P < 0.05). The supplementation of Zn affected the calcium contents in plasma, tibias and ulna, ulna phosphorus content, and linear and quadratic effects were observed, and higher values were observed with 160 mg/kg Zn supplementation than control (P < 0.05). The supplemental Zn level at 80 mg/kg increased shell effective thickness in growth stage (P < 0.05), and shell calcium and phosphorus content in initial and growth stages (P < 0.05). Dietary Zn supplementation did not affect the gene expression of Ca²⁺ transporters in the eggshell gland, but affected the expression of HCO₃^- exchanger in initial and growth stage (P < 0.05). Overall, dietary Zn supplementation could improve productive performance and shell quality in laying ducks at late phase of production, and calcium metabolism and deposition were modulated by Zn influencing HCO₃^- secretion and thus affecting shell ultrastructure and quality. A supplemental level of 80 mg/kg Zn in the diet with a basal content of 34.0 mg/kg was optimal, and higher level (160 mg/kg) decreased shell calcium deposition by depressing its metabolism.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC8628011 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description: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 Ca2+ transporter and HCO3- 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 HCO3- exchange of aged laying ducks likely contribute to age-induced ultrastructural deterioration of the eggshell.

Project description:Egg quality defects seriously reduce the quality grade and increase egg breakage in egg marketing activities. In this study, the effect of N-carbamylglutamate (NCG) on eggshell quality was investigated by evaluating calcium absorption and calcification in laying hens. A total of 30 newly hatched female Hy-Line chicks were randomly assigned to the control group (basal diet) and treatment group (basal diet supplemented with 1% NCG). At 25 wk, eggs from each group were obtained to assess egg quality parameters. Blood samples were collected for analysis of mineral, hormone, and amino acids levels at 16 h after laying egg. Uterine tissues were removed and fixed in 4% neutral paraformaldehyde solution or kept in liquid nitrogen for mineral determination, quantitative PCR, and Western blot. Results showed that the egg quality (eggshell thickness, strength and percentage, egg specific gravity, and eggshell effective thickness) was significantly increased while effective thickness of mastoid layer, width of mastoid gap, and mammillary knobs were significantly decreased by dietary NCG supplementation (P < 0.05). The levels of minerals (Ca, P, Fe, Mg, Na, K) in eggshell, plasma, and uterus were remarkably elevated (P < 0.05). Meanwhile, the concentrations of calcium metabolism-related hormones (17β-estradiol, parathyroid hormone, and calcitonin) were increased in the NCG group (P < 0.05). Moreover, expression of calbindin 1, carbonic anhydrase 2, ovalbumin, ovotransferrin, ovocleidin-17, ovocleidin-116, and clusterin mRNAs, as well as calbindin 1 and ATP2A1 proteins in uterus, duodenum, and kidney, was all upregulated in hens fed with NCG (P < 0.05). In addition, the number of blood vessels in the uterus, height of uterine mucosal folds, villus length in endometrium, and areas of uterine mucosal folds were significantly increased in the NCG group (P < 0.05). In conclusion, dietary 1% NCG supplementation during 0 to 25 wk can improve eggshell quality through changes in endometrial morphology, expression of calcium metabolism-related genes, and secretion of related hormones to promote eggshell formation in the laying hens.

Project description:Chicken eggshell (ES) waste is a rich source of calcium carbonate (CaCO3); however, the potential of ES as dietary calcium (Ca) in old laying hens has not been explored. This study compared the effects of feeding limestone, cockle shell, oyster shell, fine ES, and coarse ES as the sole Ca source on production performance, egg quality, blood biochemical constituents, and tibia characteristics in old laying hens. A total of 450 ISA-Brown laying hens at 73 wk of age with similar egg production rate (EPR) were randomly assigned to 5 treatment groups (90 hens/group, 9 hens/replicate) for 7 wk. Dietary treatment groups comprised a corn-soybean meal based diet containing different Ca sources: (i) limestone (LS; < 2 mm and 2-4 mm mixed in the ratio of 3:7) as control, (ii) cockle shell (CS; 1-4 mm), (iii) oyster shell (OS; 3-16 mm), (iv) ES fine particles (ESF; < 1 mm), and (v) ES coarse particles (ESC; 3-5 mm). Results indicated that dietary inclusion of coarse ES particles significantly increased average egg weight (P < 0.001) and daily egg mass (P < 0.05), and decreased feed conversion ratio (P < 0.001) as compared with the other treatments. However, no significant differences in EPR, feed intake, cracked egg proportion, and mortality were observed among the dietary treatments (P > 0.05). Notably, the use of ESF led to a lower proportion of cracked eggs than ESC (P < 0.05). ESC fed hens produced the heaviest eggs whereas CS fed hens produced the lightest (P < 0.001); the particle size of ES also affected the egg weight (P < 0.05). The eggs from OS and ESC fed hens showed a greater albumen height in comparison to eggs from CS group (P < 0.05); but no significant difference was observed among the LS, OS, ESF, and ESC groups (P > 0.05). The yolk color was darker in the eggs of group ESF as compared with other dietary groups (P < 0.01). However, no significant effects on Haugh units and shell properties were observed among the treatments (P > 0.05). The blood biochemistry results were not affected by the dietary Ca (P > 0.05) except for lower levels of high-density lipoprotein percentage (HDL %) in OS and ESC fed hens (P < 0.05). The tibia characteristics including weight, length, width, and breaking strength did not differ among the dietary groups (P > 0.05). However, the ESC and OS fed hens showed higher tibia bone mineral density (BMD) than the other groups (P < 0.001). In conclusion, coarse ES as a sole Ca source had beneficial effects on the production performance, egg quality, and tibia BMD in old laying hens.

Project description:BackgroundLower eggshell quality in the late laying period leads to economic loss. It is a major threat to the quality and safety of egg products. Age-related variations in ultrastructure were thought to induce this deterioration. Eggshell formation is a highly complex process under precise regulation of genes and biological pathways in uterus of laying hens. Herein, we evaluated the physical, mechanical and ultrastructure properties of eggshell and conducted RNA sequencing to learn the transcriptomic differences in uterus between laying hens in the peak (young hens) and late phase (aged hens) of production.ResultsThe declined breaking strength and fracture toughness of eggshell were observed in aged hen group compared to those in young hen group, accompanied with ultrastructure variations including the increased thickness of mammillary layer and the decreased incidence of early fusion. During the initial stage of eggshell formation, a total of 183 differentially expressed genes (DEGs; 125 upregulated and 58 downregulated) were identified in uterus of laying hens in the late phase in relative to those at peak production. The DEGs annotated to Gene Ontology terms related to antigen processing and presentation were downregulated in aged hens compared to young hens. The contents of proinflammatory cytokine IL-1β in uterus were higher in aged hens relative to those in young hens. Besides, the genes of some matrix proteins potentially involved in eggshell mineralization, such as ovalbumin, versican and glypican 3, were also differentially expressed between two groups.ConclusionsAltered gene expression of matrix proteins along with the compromised immune function in uterus of laying hens in the late phase of production may conduce to age-related impairments of eggshell ultrastructure and mechanical properties. The current study enhances our understanding of the age-related deteriorations in eggshell ultrastructure and provides potential targets for improvement of eggshell quality in the late laying period.

Project description:This study investigated that circadian zinc (Zn) feeding regime affected laying performance, Zn and calcium (Ca) status, antioxidant capacity and gene expression of circadian clock, and Ca and Zn transporter in laying hens. In total, 162 of 21-wk Hyline Sophie laying hens were assigned randomly into 3 groups including CON group (Control Zn, basal diets supplemented 60 mg/kg Zn), HL group (high-low Zn, basal diets supplemented 120 mg/kg Zn-basal diets), and LH group (low-high Zn, basal diets-basal diets supplemented 120 mg/kg Zn), which were fed at 0,530 h and 1,530 h, respectively. Blood, tibia, duodenum, and eggshell gland samples were collected at 8 h intervals with starting at 0,000 h in 1 d after 10 wk of experiment. Compared with CON group: 1) Feed conversion ratio (FCR) of LH and HL group decreased significantly (P < 0.05); 2) in serum, total antioxidant capacity and CuZn-superoxide dismutase (SOD) at 0,000 h increased significantly, as well as Ca and Zn concentration of tibia at 0,800 h in LH group (P < 0.05); 3) in duodenum, mRNA expression of calbindin-d28k (CaBP) and NCX1 at 1,600 h in HL group upregulated significantly, as well as Per2 and Per3 at 0,000 h, CLOCK, Cry2, Per2, and Per3 at 1,600 h (P < 0.05). But, Zn5 at 0,800 h in HL group downregulated significantly (P < 0.05). 4) In eggshell gland, the mRNA expression of CaBP at 0,000 h and Zn5 at 1,600 h in HL group downregulated significantly (P < 0.05). However, SOD at 1,600 h in HL group upregulated significantly, as well as Cry1 and Per3 at 0,800 h in HL group upregulated significantly (P < 0.05). In conclusion, circadian Zn feeding diet regime was beneficial to improvement of FCR. The regulation of laying hens' circadian rhythms affected Zn and Ca transporter and interrelationship between Ca and Zn metabolism, also altered antioxidant capacity in present study. Therefore, circadian Zn feeding regime can be considered as a new method to improve laying performance in laying hens.

Project description:Calcium (Ca) and phosphorus (P) transporters are responsible for their absorption and transport in small intestine and kidney, contributing to eggshell formation. The light-dark cycle is a primary cue in the reproduction of laying hen. In this study, we investigated the effect of different light-dark programs on eggshell quality and the expression of genes related to Ca and P transportation in laying hens. Seventy-two 56-week-old laying hens were randomly divided into two groups and reared at 16-h light and 8-h dark (control) or 9-h light and 15-h dark regime (long dark phase, LDP). The expressions of calcium transporter calbindin-D28k (CaBP-D28k), plasma membrane Ca ATPase 1b (PMCA1b), and phosphorus transporter NaPi-IIb (NPt2b) and NaPi-IIa (NPt2a) were measured in the small intestine, kidney, and eggshell gland. The results showed that feed intake (P < 0.001) and egg weight (P = 0.05) were decreased by LDP treatment. Compared with control, the eggshell hardness was increased (P = 0.011) by LDP treatment, but the eggshell thickness and the percentage of eggshell were not changed. The Ca and P contents in eggshell were increased by LDP treatment. During the scotophase, LDP-hens showed higher serum Ca (P = 0.0056) and P levels (P = 0.079) but lower alkaline phosphatase (ALP) activity than that of control hens. In the duodenum, the relative higher expression of CaBP-D28k and PMCA1b in scotophase compared to photophase was masked by LDP treatment. The expression of CaBP-D28k and osteopontin (OPN) in the eggshell gland were increased by LDP treatment, compared to control hens. In the jejunum, the protein expression levels of CaBP-D28k and PMCA1b decreased during photophase in LDP-hens. The result indicates that the increased blood Ca and P concentration during scotophase by LPD treatment is beneficial to the deposition of Ca and P in the eggshell. The result offers an alternative strategy for managing laying hens with poor eggshell quality.

Project description: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.

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Dietary zinc supplementation affects eggshell quality and ultrastructure in commercial laying ducks by influencing calcium metabolism.

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