UNPARALLELED CHANGES IN CORTICOSTERONE AND TESTOSTERONE EXCRETION IN JAPANESE MALE QUAIL UNDER SHORT PHOTOPERIOD MAY UNDERLIE INTERINDIVIDUAL REPRODUCTIVE VARIATION

DOMINCHIN MF; BUSSO JM; PALME RUPERT; MARIN RH

Cusco

Congreso; IX Congreso de Ornitología Neotroppical; 2011

Neotropical Ornithological Society & Unión de Ornitólogos de Perú

In many birds, it has been postulated that populations of a given species may differ in their responsiveness to photoperiod, but the details of hormone activity underlying reproductive physiological process remain unspecified. At present, increasing day-length (photoperiod) is positively correlated with adrenal and gonadal functions in quail. The objective was to noninvasively determine whether differences in the cloacal gland responses in quail during short days are related to different levels of adrenocortical and/or testicular activity. At 8 weeks of age, a group of 51 individually male Japanese quail was exposed to a short photoperiod stimulation (16 hs dark: 8 hs light) and water ad libitum, and under controlled temperature. After 5 weeks, they were classified as high or low photo-sensitive (HPS and LPS, respectively) according to whether or not they showed a reduction in cloacal gland volume (menor 1000 mm3) and stop producing cloacal foam. Another group of 29 birds was kept as a control under long photoperiod (8D:16L) and termed non-classified (NC). To evaluate the gonadal and adrenal endocrine activity, a cortisone EIA measuring corticosterone metabolites with a 3,11-dione structure, and an epiandrosterone EIA measuring 17-oxoandrogen metabolites were used. Interestingly, under short photoperiod, while corticosterone metabolites in excreta were different between HPS and LPS males, and both groups exhibited lower hormone values than their NC males counterparts (NC mayor LPS mayor HPS; P menor 0,0001), the excretion of androgen metabolites showed a different pattern. That is, LPS males exhibited similar high hormone values NC males and higher than HPS males (NC=LPS mayor HPS; P menor 0,0001). The results suggest that unparalleled changes in adrenal and gonadal endocrine activity would be acting as modulators of physiological photoperiodic reproductive processes allowing a subpopulation of males (the LPS ones) to quickly overcome the environmental light constraints.