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Shell formation and bone strength in laying hens

effects of age, daidzein and exogenous estrogen

Wistedt, Anna (2013). Shell formation and bone strength in laying hens. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2013:88
ISBN 978-91-576-7914-7
eISBN 978-91-576-7915-4
[Doctoral thesis]

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In Sweden almost 3.8% of all eggs are ruined due to cracked eggshells as shell quality declines with age during the laying period. This is a concern for food safety as well as an economical problem. Parallel with reduced shell quality the bone strength declines to an extent that the animal's welfare is threatened.

Laying hens of Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) were monitored during a complete production period. The first sign of declining shell quality was found in mid-production in both hybrids, and even before, in peak production, decreasing bone strength was detected. An imbalance between estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) in the shell gland and a reduced density of tubular glands are suggested as factors involved in the age-related decline of shell quality. Since the majority of eggshell calcium is absorbed in the duodenum, the dramatic drop in active carbonic anhydrase (CA) seen in duodenum at mid-production, may also contribute. In the shell gland CA is considered a key enzyme in the supply of the carbonate ions needed for shell formation. However, CA in the shell gland did not primarily seem to be involved in declining shell quality, in fact number of capillaries positive for CA activity increased with age. The calcium transporter PMCA was located in shell gland and duodenum but was not altered by age.

Boosting laying hens with a low continuous dose of estradiol at the end of the laying period improved shell quality in both hybrids, while a daidzein supplementation (50mg/kg feed) in the feed did not. Bone strength was unaffected by both treatments. CA activity in the shell gland may be regulated by estrogen and daidzein, possibly by acting via ERβ. However, a difference in sensitivity to daidzein and estradiol was found between the hybrids which complicates the interpretation of results and must be taken into a count when comparing studies from other investigations.

Authors/Creators:Wistedt, Anna
Title:Shell formation and bone strength in laying hens
Subtitle:effects of age, daidzein and exogenous estrogen
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2013
Number of Pages:73
I.Wistedt, A. Ridderstråle, Y. Wall, H. Holm, L. (2012). Effects of phytoestrogen supplementation in the feed on the shell gland of laying hens at the end of the laying period. Animal Reproduction Science 133(2012), 205-213.
II.Wistedt, A. Ridderstråle, Y. Wall, H. Holm, L. Age related changes in the shell gland and duodenum in relation to shell quality and bone strength of laying hens. Submitted to Animal Reproduction Science.
III.Wistedt, A. Ridderstråle, Y. Wall, H. Holm, L. Exogenous estradiol improves shell strength in laying hens at the end of the laying period, possibly through regulation of estrogen receptor ratio and carbonic anhydrase. Submitted to Acta Veterinaria Scandinavica.
Place of Publication:Uppsala
Publisher:Institutionen för anatomi, fysiologi och biokemi, Sveriges lantbruksuniversitet
ISBN for printed version:978-91-576-7914-7
ISBN for electronic version:978-91-576-7915-4
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L02 Animal feeding
L Animal production > L53 Animal physiology - Reproduction
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Agrovoc terms:layer chickens, breeds (animals), eggs, egg shell, strength, quality, phytooestrogens, daidzein, feed supplements, duodenum, carbonate dehydratase, bone diseases, laying performance, age
Keywords:Laying hens, shell gland, shell formation, shell quality, bone strength, duodenum, carbonic anhydrase, estrogen, phytoestrogen, estrogen receptor α, estrogen receptor β, plasma membrane calcium ATP-ase
Permanent URL:
ID Code:10894
Department:(VH) > Dept. of Anatomy, Physiology and Biochemistry
External funders:FORMAS
Deposited By: Anna Wistedt
Deposited On:21 Nov 2013 09:14
Metadata Last Modified:14 Dec 2014 03:15

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