Growth and innate immunity are not limited by selection for high egg testosterone content in Japanese quail

Abstract

SUMMARYThe effects of maternal androgens on fitness-related traits of offspring are generally assumed to be epigenetic adaptations to the environment that may be encountered by the next generation. Possible constraints of high yolk androgen transfer are still not understood, although a suppressed immune response in offspring is frequently considered. The aim of our study was to examine the innate immune defence in high (HET) and low egg testosterone (LET) lines of Japanese quail, which differ in the hormonal milieu of their eggs, thus providing a good physiological model for the study of androgen-mediated maternal effects. Acute phase response was induced by a lipopolysaccharide injection in 12-day-old quail and plasma corticosterone and the heterophil:lymphocyte ratio were measured at 1 and 3h post-treatment. Basal levels of non-specific antibodies (IgY) were determined in the circulation. We found that HET quail were heavier than LET quail from the second week of age, indicating enhanced post-hatching growth. At 1h post-lipopolysaccharide challenge, plasma corticosterone concentrations increased in the HET but not in the LET line. The heterophil:lymphocyte ratio rose in both lines at 3h post-immune challenge, with a more pronounced response in HET quail. Moreover, HET chicks displayed higher IgY levels than LET chicks, suggesting either enhanced passive immunoprotection or stimulated endogenous antibody production. In conclusion, our data demonstrate that the genetic selection for high egg testosterone content positively influences growth and, simultaneously, does not limit the acute phase response in young quail.

Selection for High Egg Testosterone and Immune Response of Young Japanese Quail under Mild Food Restriction

“…Differences in body mass in favour of HET as compared to LET quail were discernible at the end of the second week after hatching and were similar to the growth rates that we recorded in our previous studies (Okuliarova et al, 2011a;Kankova et al, 2012). The data also indicate that the different growth rate between lines persists under mild food shortage and is not present only under optimal food conditions.…”

“…Dried blood smears were fixated and stained with May-Grünwald and Giemsa-Romanowsky solutions (Kankova et al, 2012). Final differential count of white blood cells (WBC) was determined as percentages of heterophils (He), lymphocytes (Ly), eosinophils, monocytes and basophils per 200 leukocytes on each slide.…”

“…Plasma corticosterone concentrations were measured by radioimmunoassay using a corticosterone rat/mouse 125 I-labelled RIA kit (DRG Instruments GmbH, Marburg, Germany) that was validated for the measurement of quail plasma samples in our laboratory (Kankova et al, 2012). All samples were run in a single assay with an intra-assay variation coefficient of 0.5%.…”

“…Studies performed in precocial birds under controlled conditions, have not shown any significant detrimental effects of mT on the immune system (Andersson et al, 2004;Kankova et al, 2012). However, experiments in Coturnix chinensis showed that mT negatively influenced cell mediated immune response in chicks with fast body growth (Andersson et al, 2004).…”

Genetic differences in yolk testosterone levels influence maternal hormone deposition in the second laying cycle in Japanese quails

“…In precocial birds, experimental in ovo injection of T resulted in significant effects on physiology (Cucco et al, 2008) and on the behavioural phenotype of young chicks (Daisley et al, 2005;Okuliarova et al, 2007;Bertin et al, 2008). Moreover, our previous experiments showed that the selection for high egg T content positively affected post-hatching growth (Okuliarova et al, 2011b), whereas elevated growth rate was not compromised by a weaker innate immune response in the HET as compared with the LET quail chicks (Kankova et al, 2012). Therefore, the increase of yolk T concentrations in the second laying cycle in the HET females may reflect an improvement of their breeding value between cycles that together with the better prospects of experienced females to cope with a stable environment can increase their reproductive success.…”