Testosterone manipulation post-castration does not alter cloacal gland growth differences in male quail selected for divergent plasma corticosterone stress response

BUSSO, J. M.; SATTERLEE, D. G.; ROBERTS, M. L.; BUCHANAN, K. L.; EVANS, M. R.; MARIN, R. H.

POULTRY SCIENCE

POULTRY SCIENCE ASSOC INC

Lugar: USA; Año: 2010 p. 2691 - 2698

0032-5791

Japanese quail selected for reduced (low stress, LS) rather than exaggerated (high stress, HS) plasma corticosterone response to brief restraint have consistently shown greater cloacal gland (CG) development, an androgen-dependent trait. In this study, the effects of testosterone (T) implants on levels of plasma T and CG development in castrated LS and HS quail were determined. Stress line males were castrated and randomly allocated to 1 of 3 testosterone treatments: empty T (ET), low T (LT), and high T (HT) implant groups. CG volume (CVOL) was determined at four weekly intervals that represented ranges of from 1-9, 8-17, 15-24 and 22-31 d post-castration and T implantation. Levels of plasma T were also assessed at the end of the study. Development of the CG was affected by quail line (LS > HS), T treatment (HT > LT > ET) and time of measurement (1-9 < 8-17 < 15-24 d = 22-31 d post-castration and T implantation). A significant interaction between T treatment and time of measurement on CVOL was also detected (CVOL generally increasing with time in LT and HT but not ET treated quail). However, even though HT implant treatments induced higher CG development than did LT treatments beyond the first interval of CVOL measurement, and despite the finding of greater CVOLs in LS than HS quail during the last two measurement intervals within each of the LT and HT groups, no interaction was observed between T implant dosages and quail stress line on CVOL. Thus, by the end of the study, regardless of T dose, CVOL was consistently greater in LS quail than in their HS counterparts. Also, while, as expected, T implant treatment significantly altered levels of plasma T (HT > LT > ET), neither quail line nor its interaction with T treatment affected plasma T. The present findings suggest that the often-observed depressed CG development in the HS line may be independent of T effects.