Effects of zeitgeber shifts on gonadal function in male domestic fowls.

ABSTRACT

Effects of shifting light dark (LD) schedule of 8 hr/week on comb height and gonadal development were investigated in male domestic fowls. Three-day-old birds were exposed to repeated delay (westward shift) or repeated advancement (eastward shift) of the LD schedule at weekly intervals till they attained the age of 20 weeks. Control birds were held in fixed LD 1212 hr light/dark schedule. Comb height was monitored at weekly intervals beginning at the age of 7 weeks. At 12th, 16th and 20th week 5 birds from each schedule were sacrificed and gonadal volume was recorded. Results indicate that comb and gonadal growth were significantly higher in advance-schedule birds when compared with control and delay-schedule birds. Histologically, testes of advance-schedule birds were more active when compared with those of control and delay-schedule birds. It appears that the eastward shifts of the synchronizer schedule may exert stimulatory influence on gonads.