Effect of Estrogen on Yolk Deposition and Atresia of Ovarian Follicles in Hypophysectomized Hens.

Nakada, Tadashi; Asato, Liu; Oikawa, Takuro; Koja, Zuiko; Tanaka, Kousaku

doi:10.2141/jpsa.31.162

Cited by 1 publication

(1 citation statement)

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“…In the current study, similar results were obtained: the albumen height and Haugh unit were improved in the groups administered low levels of dietary Cd (7.58 mg/kg) after 3 wk of treatment (P < 0.05) compared with the control group (0.47 mg/kg), and the positive of Cd impact on yolk color and eggshell thickness continued even with long-term Cd treatment (9 wk; Table 3). The reason may be associated with the function of Cd to mimic the effects of estrogen, which could maintain yolk deposition (Nakada et al, 1994) and enhance the synthesis of yolk precursors (Li et al, 2014). There is no explanation for the positive impact on albumen quality and eggshell thickness.…”

Section: Egg Quality and CD Residues In Tissues And Eggsmentioning

confidence: 99%

Dietary cadmium chloride impairs shell biomineralization by disrupting the metabolism of the eggshell gland in laying hens

Zhu

Miao

et al. 2020

Journal of Animal Science

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In this study, we identified cadmium (Cd) as a potential endocrine disruptor that impairs laying performance, egg quality, and eggshell deposition and induces oxidative stress and inflammation in the eggshell glands of laying hens. A total of 480 38-wk-old laying hens were randomly assigned into 5 groups that were fed a basal diet (control) or a basal diet supplemented with Cd (provided as CdCl2·2.5 H2O) at 7.5, 15, 30, and 60 mg Cd per kg feed for 9 wk. The results showed that, when compared with the control group, a low dose of dietary Cd (7.5 mg/kg) had positive effects on egg quality by improving albumen height, Haugh unit, yolk color, and shell thickness at the third or ninth week. However, with the increase in the dose and duration of Cd exposure, the laying performance, egg quality, and activities of eggshell gland antioxidant enzymes (catalase [CAT], glutathione peroxide [GSH-Px]), and ATPase (Na+/K+-ATPase, Ca2+-ATPase, and Mg2+-ATPase) deteriorated, and the activity of total nitric oxide synthase (T-NOS) and the level of malondialdehyde (MDA) increased significantly (P < 0.05). The histopathology and real-time quantitative PCR results showed that Cd induced endometrial epithelial cell proliferation accompanied by upregulation of the mRNA levels of progesterone receptor (PgR) and epidermal growth factor receptor (EGFR), downregulation of the mRNA levels of estrogen receptor α (ERα) and interleukin 6 (IL6), and inflammation of the eggshell gland accompanied by significantly increased expression of complement C3 and pro-inﬂammatory cytokine tumor necrosis factor α (TNFα) (P < 0.05). In addition, the ultrastructure of the eggshell showed that dietary supplementation with 7.5 mg/kg Cd increased the palisade layer and total thickness of the shell, but with the increase in dietary Cd supplementation (30 and 60 mg/kg) the thickness of the palisade layer and mammillary layer decreased significantly (P < 0.05), and the outer surface of the eggshell became rougher. Correspondingly, the expression of calbindin 1 (CALB1), ovocalyxin-32 (OCX-32), ovocalyxin-36 (OCX-36), osteopontin (SPP1), and ovocledidin-17 (OC-17) decreased significantly (P < 0.05) with increasing dietary Cd supplementation. Conclusively, the present study demonstrates that dietary supplementation with Cd negatively affects laying performance, egg quality, and eggshell deposition by disturbing the metabolism of eggshell glands in laying hens but has a positive effect on egg quality at low doses.

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Section: Egg Quality and CD Residues In Tissues And Eggsmentioning

confidence: 99%