Master of Science (MS)
Animal Science (Animal, Dairy, and Poultry Sciences)
Unstressed and stressed quail hens selected for exaggerated (HS, high stress) rather than reduced (LS, low stress) plasma corticosterone (B) response to brief restraint deposit more B into their eggs than do their LS hen counterparts. HS hens implanted with B also show reduced egg lay when compared to LS- and HS-control and LS-B-implanted hens. Herein, the effects of stress line on length of egg incubation (LEI) and chick body weight at emergence (BWTE) (Exp. 1) and the interactive influences of line with maternal B-treatment (sub-Q control, CON-, or B-implants) on LEI (Exp. 2) and on egg fertility (FERT), total (TOTHATCH) and fertile (FRTHATCH) egg hatchability, and the percentages of early (ED) and late (LD) dead embryos and pipped (PIP) eggs (Exp. 3) were determined. In Exps. 1 (P < 0.0003) and 2 (P < 0.0001), mean LEI was shorter for eggs laid by HS than LS hens, while chick BWTE was unaffected by line (Exp. 1). In Exp. 2, B-implanted hen eggs also hatched sooner (P < 0.0001) than did CON eggs and line*hen B-implant treatment affected (P < 0.05) the LEI as follows: LS-CON > LS-B > HS-CON > HS-B. In Exp. 3, FERT and TOTHATCH were dramatically reduced (P < 0.0001; both cases) in eggs of HS compared to LS hens and in eggs of B-implant compared to CON hens (P < 0.0001 and P < 0.0002, respectively). Line*implant treatment FERT and TOTHATCH means differed (P < 0.05) as follows: LS-B = LS-CON > HS-CON > HS-B and LS-CON = LS-B = HS-CON > HS-B, respectively. Although FRTHATCH and ED was unaffected by the main treatments, HS-B-implanted hen eggs had more (P < 0.05) EDs. LD embryo and PIP egg percentages were unaffected. The stress line*maternal B findings are important to avian geneticists as they further emphasize the benefits that selection for reduced adrenocortical responsiveness has on hen reproductive performance and they warn poultry producers that stress in the laying barn may abbreviate egg incubation periods and negatively affect egg FERT, TOTHATCH, and ED embryos, particularly in hens genetically predisposed towards high stress responses.
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Schmidt, Jason Berante', "Influences of maternal corticosterone on incubation length and hatchability of eggs laid by quail hens selected for divergent adrenocortical stress responsiveness" (2008). LSU Master's Theses. 3836.