The rapid-growth phase demands a great amount of Ca from blood and occurs during the night in laying hens. The next 12 hours make up the rapid-growth phase with linear deposition of eggshell and the terminal phase, just 2 hours before oviposition, is characterized by the arrest of calcification and the deposition of the cuticle. The first 10 hours after ovulation make up the initial phase, with the slow secretion of CaCO 3 to the uterine lumen. p.813-59.), and can be divided into 3 distinct phases. Mechanisms and hormonal regulation of shell formation: supply of ionic and organic precursors, shell mineralization. This process occurs in the lumen of the uterus, is based in a large amount of daily calcium and bicarbonate secretion ( Nys et al., 2021 Nys Y, Gautron J, Rodriguez-Navarro AB, Hincke M. World's Poultry Science Journal 2012 68:71-82.).Īvian eggshell formation is one of the most rapid biomineralization processes know in nature. Concepts and methods for understanding bone metabolism in laying hens. Kim et al., 2012 Kim WK, Bloomfield SA, Sugiyama T, Ricke SC. Metabolic Bone Disease and Related Research 1984 5:191-3. Changes in activity of chicken medullary bone cell populations in relation to the egg-laying cycle. In this sense, female birds develop an integrated metabolism among bones, intestine, kidneys, and hormones to maintain blood calcium levels during the daily egg formation cycle ( Van De Velde et al., 1984 Van De Velde JP, Vermeiden JPW, Touw JJA, Veldhuijzen JP. Overview of bone biology in the egg-laying hen. The calcified eggshell with a great amount of calcium is secreted by uterus mucosa during the hours of eggshell formation ( Whitehead, 2004 Whitehead CC. The morphological description of genital organs in quail is also general and does not explore the differences during functional phases.ĭaily egg-cycle in avian females in the active reproduction period lasts around 24-25 hours, including ovulation of the oocyte in the ovary and production and secretion of the egg part in the oviduct ( Nys et al., 2021 Nys Y, Gautron J, Rodriguez-Navarro AB, Hincke M. Comparative Biochemistry & Physiology (Part A Molecular and Integrative Physiology 2009 152(4) 447-9.). Calcium transport in strongly calcifying laying birds: mechanism and regulation. Disrupted carbonic anhydrase distribution in the avian shell gland following in ovo exposure to estrogen. The general metabolism of egg formation in quails is similar to laying hens, but with ovulation and oviposition in the afternoon, and most calcification of the shell period during the day ( Holm et al., 2001 Holm L, Berg C, Brunström B, Ridderståle Y, Brandt I. Quails are taken to be comparable to laying hens in reproductive physiology, but their egg-laying period places them at a different physiological moment. In conclusion, eggshell secretion in light periods, high magnum activity and medullary bone Ca deposition during midday and afternoon, as well as the ovulation/oviposition in the afternoon, are the main characteristics of the distinct physiological aspects of the egg cycle in quails.Ĭalcium bone strength femur medullar bone eggshell Analysis of the eggshell using scanning electron microscopy evidenced that palisade layer formation starts during the night (8-14 hrs POV), and most parts are secreted during the day period. Egg-cycle period affected the Ca% of the medullar bone of the femur and tibiotarsus, with the lowest mean at 14 hrs POV (06h00), and the highest mean after oviposition (0 hr POV), showing the recovery of Ca stores in long bones for the next egg cycle. Serum albumin and total Ca had the highest value in the 2 hrs group, and the lowest in 8 and 14 hrs groups. The magnum had higher relative weight before the next ovulation (20 and 0 hr POV), and its tubular glands showed functional variation through periods: abundant eosinophilic, PAS+, and negative Alcian blue secretion at 0 and 2 hrs, empty glands aspect at 4 hrs, and filled again at 20 hrs POV. Sixty quails (18-wk) were distributed in 6 groups according to hours post-oviposition (POV): 0 hr POV (16h00), 2 hrs POV (egg in magnum), and 4, 8, 14, and 20 hrs POV (egg in uterus). This study described changes in the serum biochemistry, morphology of genital organs, long bone, and eggshell during the daily egg formation cycle in Japanese quails.
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