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United States Department of Agriculture

Agricultural Research Service

Research Project: SAFEGUARDING WELL-BEING OF FOOD PRODUCING ANIMALS Title: Development of an enzyme-linked immunosorbent assay for detection of chicken osteocalcin and its use in evaluation of perch effects on bone remodeling in caged White Leghorns

Authors
item Jiang, Sha -
item Cheng, Heng Wei
item Hester, Patricia -
item Hou, Jiaying -

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 2013
Publication Date: May 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/57072
Citation: Jiang, S., Cheng, H., Hester, P.Y., Hou, J.F. 2013. Development of an enzyme-linked immunosorbent assay for detection of chicken osteocalcin and its use in evaluation of perch effects on bone remodeling in caged White Leghorns. Poultry Science. 92:1951-1961.

Interpretive Summary: Osteocalcin is a sensitive biochemical marker for evaluating bone turnover in mammals. The role of osteocalcin in chickens is less clear because of a need for a chicken assay. A chicken osteocalcin assay was developed in this study. The intra- and inter-assay differences were smaller than 7% and 12%, respectively. The sensitivity of the developed osteocalcin assay was higher than a commercial rat-mid osteocalcin assay which reacts with multiple species including chickens. Exercise-associated bone remodeling was detected by using the developed assay. Data showed that at 71 week of age hens with perch access had higher concentrations of osteocalcin than hens without perches during egg laying. The results indicated that the assay is sensitive and accurate with adequate discriminatory power for measuring bone remodeling in chickens. The method may be used by egg producers to monitor chickens’ bone development associated with managements for improving chicken health.

Technical Abstract: Osteocalcin (OC) is a sensitive biochemical marker for evaluating bone turnover in mammals. The role of avian OC is less clear because of a need for a chicken assay. Our objectives were to develop an assay using indirect competitive ELISA for detecting chicken serum OC and use the assay to examine the effects of perches on bone remodeling in caged hens. Anti-chicken OC polyclonal antibody was produced by immunization of rabbits with a recombinant OC from Escherichia coli. Chicken OC extracted from bone was used as a coated protein, and purified chicken OC was used for calibration. The limit of detection of the developed OC ELISA was 0.13 ng/mL. The intra- and inter-assay CV were < 7% and < 12%, respectively. The sensitivity of the developed OC ELISA was compared with a commercial Rat-Mid OC ELISA in laying hens housed in conventional cages with or without perches. Serum samples were collected from 71-wk-old White Leghorn hens subjected to 4 treatments. Treatment 1 was control chickens that never had access to perches during their life cycle. Treatment 2 chickens had perches during the pullet phase (0 to 16.9 wk of age); whereas, treatment 3 chickens had perches only during the egg laying phase of the life cycle (17 to 71 wk of age). Treatment 4 chickens always had access to perches (0 to 71wk of age). Correlation between the 2 assays was 0.62 (P < 0.0001). Levels of serum OC using the developed chicken ELISA were higher than that detected using the Rat-Mid ELISA (P < 0.0001). Results from the chicken ELISA assay showed that hens with perch access had higher concentrations of serum OC than hens without perches during egg laying (P = 0.04). Pullet access to perches did not affect serum OC levels in 71-wk-old hens (P = 0.15). In conclusion, a chicken OC ELISA has been validated that is sensitive and accurate with adequate discriminatory power for measuring bone remodeling in chickens.

Last Modified: 12/18/2014
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