Photoperiod-Induced Changes in Cloacal Gland development in male Japanese quail classified at 11 days of age according to their preference to remain in close proximity to conspecifics.

MF DOMINCHIN, DA GUZMÁN, RH MARÍN, JM BUSSO

Campos do Jordao

Congreso; 25th International Ornithological Congress; 2010

In birds, seasonal changes in daylength syncronize breeding activity. On short days they fall out of reproductive condition, however not all do. This study evaluates the relationship between early social responses and photo-induced reproductive changes and the timing of photorefractoriness. Male birds were classified considering two criteria i) at 11 days of age, according to whether they were found in close proximity to a high (12 chicks, HD) or low (3 chicks, LD) density of confined conspecifics; ii) at 16 weeks of age according to their reproductive performance following 5 weeks of photoinhibition: birds that showed a reduction in the cloacal gland volume (CG) to < 1000mm3 and no foam production (FP) were termed high photo-sensitive (HPS); the remaining males were termed low photo-sensitive (LPS). Quail were photostimulated (long days;16L:8D) from 4 to 11 and 23 to 28 weeks of age and photoinhibited (short days; 8L:16D) from 12 to 22 weeks of age. CG and FP were measured weekly. As expected, CG development and FP increased significantly from 4 to 11 weeks of age. According to the photo-response classification criteria, highly significant differences in CG measurements were detected between HPS and LPS quail after 2 weeks of photo-inhibition. Both HD and LD categorized groups presented a similar number of individuals with either HPS or LPS CG response patterns. However, while LPS-HD and LPS-LD quail showed similar and higher CG volumes, the HPS-LD males compared to their HPS-HD counterparts showed an accelerated (5 weeks advanced) CG volumen spontaneous recovery. After 4 weeks of relighting, all groups showed similar maximum CG developments. The results indicate that gonadal photorefractorines in short daylength season interact with the quail´s early social grouping strategy.