Age-related changes in the shell gland and duodenum in relation to shell quality and bone strength in commercial laying hen hybrids

Abstract

BackgroundDuring the production period of laying hens, the number of cracked eggshells increases and the skeleton becomes brittle. Both these problems are related to ageing of the hen and cause economic problems for egg producers and impaired animal welfare. This study investigated key factors in the shell gland and duodenum related to eggshell quality and bone strength in laying hens during the production period. Five Lohmann Selected Leghorn (LSL) and five Lohmann Brown (LB), common hybrids in commercial egg production, were euthanized at 21, 29, 49 and 70 weeks (wk) of age. Blood samples for analysis of total calcium were taken at euthanization. Right femur and humerus were used for bone strength measurements and tissue samples from shell gland and duodenum were processed for morphology, immunohistochemical localisation of oestrogen receptors (ERα, ERβ), plasma membrane calcium ATPase (PMCA) and histochemical localisation of carbonic anhydrases (CA). Eggs were collected for shell quality measurements.ResultsAt age 49 week, shell and bone strength had both deteriorated, but the hens were then able to maintain the level until 70 week of age and femur bone strength even improved. The main physiological findings associated with the effects seen at 49 week were reduced gland density and a shift in balance between ERα and ERβ in the shell gland, which coincided with a reduction in CA activity in the duodenum. Somewhat surprisingly, capillary density and capillaries with CA activity both increased in the shell gland over time, the latter possibly mediated via ERβ. These findings were independent of hybrid. PMCA was found in both shell gland and duodenum, but appeared unrelated to the age-related changes in shell and bone quality.ConclusionsIn hens around half-way through the production period, both shell quality and bone strength had deteriorated. Decreased gland density and a shift in the balance between ERα and ERβ in the shell gland, co-occurring with a dramatic drop in duodenal CA activity, are suggested as possible factors involved in age-related changes in shell and bone quality.Electronic supplementary materialThe online version of this article (10.1186/s13028-019-0449-1) contains supplementary material, which is available to authorized users.

Integument, mortality, and skeletal strength in extended production cycles for laying hens – effects of genotype and dietary zinc source

“…However, it is possible that some regeneration of structural bone occurred in the latter part of the production period, when egg production declined and days out of lay became more frequent. An improvement in tibial bone breaking strength during the production cycle has been observed in other studies (Leyendecker et al, 2005;Wistedt et al, 2019). 2004) concluded that the length of time that birds are in a continuously reproductive state is likely to be significant for degree of osteoporosis, and that short periods out of lay may allow regeneration of structural bone.…”

Transcriptome analysis and identification of age-associated fertility decreased genes in hen uterovaginal junction

“…For female birds, such as layers, broilers, quails, and turkeys, the oviduct plays a more specific role in the breeding process. For example, the quality of the albumen and egg shell is mainly related to the function of magnum and uterine tissues, respectively ( Herrera et al., 2018 ; Wistedt et al., 2019 ). The decreasing efficiency of SSTs in UVJs caused by aging is regarded as another main factor affecting the decline of fertility rate in both breeders of layers and broilers ( Beaumont et al., 1992 ; Fasenko et al., 1992 ; Gumulka and Kapkowska, 2005 ).…”

Transcriptome analysis revealed the effect of selenium yeast on improving eggshell quality in aged laying hens

“…The carbonate ion required for eggshell synthesis is catalyzed by carbonic anhydrases (CA), and uterine glandular cells possess the carbonic anhydrase activity sites. Growing evidence has demonstrated that high level of CA2 expression play a pivotal role for conversion of intracellular CO 2 to HCO 3 − in chicken [53,54]. As a member of the otopetrin gene family, OTOP2 gene may have similar functions to OTOP1, which regarded as modulator of cellular calcium in ux [55], to transport calcium across the uterine epithelium for eggshell calci cation [56].…”