Cloacal gland and testicular endocrine differences in male Japanese quail with similar adrenocortical activity during short days

DOMINCHIN MF; BUSSO JM; PALME R; MARIN RH

Nantes

Congreso; XVIIIth Congress of the World Veterinary Poultry Association; 2013

World Veterinary Poultry Association

Photoperiod is one of the most powerful environmental cues for synchronizing physiological states in birds. There is a wide variety of artificial lighting regimes in poultry breeding, often birds are reared under nearly continuous lighting. Some reports indicate that reducing photoperiod could even improve welfare issues. However, because reproduction is strongly controlled by photoperiod length, shorter light exposure can alter breeding physiology and affect performance. Interestingly, in Japanese quail not all birds regress reproductive functions when exposed to short days and therefore, they can be classified as either non-responsive or responsive to lighting manipulation offering an interesting tool to assess reproductive physiology. This study determines the temporal variation pattern of testicular and adrenocortical activity in male quail non-responsive and responsive to short days and in comparison to counterparts maintained under long days. Until full reproductive development, birds were reared under long stimulatory photoperiod (14L:10D). At 11 weeks of age, birds were either assigned to short days (8L:16D) or remained under long days (Controls). After 5 weeks of short days, males were classified as either Non-responsive or Responsive, considering whether the cloacal gland volume was above or below 1000 mm3 (and with or without foam production), respectively. Weekly measurements of cloacal gland volume, foam production, and fecal androgen and corticosterone metabolites (by enzyme immunoassays) were made from 10 to 30 weeks of age, thus ranging from pre- to post- photoperiod manipulation. Repeated measure ANOVAs showed no measurement differences before photoperiod manipulation. After classification, cloacal gland profiles were similar in Non-responsive and Control quail, but significantly greater (P<0.001) than in their Responsive counterparts. Androgen metabolites concentrations were found to be lower in the Responsive than in the Non-responsive males, and both groups showed lower concentrations than Controls (P<0.001 in all cases). Corticosterone metabolites concentrations were also significantly affected (P<0.001) by photoperiod. Interestingly, differences between Non-responsive and Responsive quail were only found between 2-5 weeks post- photoperiod reduction. Results show unparalleled changes in adrenal and testicular endocrine activity that could be acting as modulators of reproductive physiology allowing Non-responders males to overcome quickly the environmental challenge of photoperiod reduction