Photoperiodic-dependent Morpho-biometric changes in the Excurrent Duct System of Sexually Mature Helmeted Guinea Fowl (Numida meleagris)

Abstract

Photoperiod is considered to be one of the most effective environmental factors controlling the reproductive cycle and gonadal maturation in some  mammalian species. However, very limited information is available on its effects on reproductive biology of the helmeted guinea fowl (Numida  meleagris). Thus, we investigated the effects of varying photoperiods on morphobiometry of the excurrent duct system of Numida meleagris. Sexually-  mature male helmeted guinea fowls (n=21), were randomly assigned into three (3) photoperiodic regimes of seven birds per group (n=7); viz [Group I:  Short daylight (SD) with; 8 Hour of light (HL), Group II: Moderate daylight (MD; 12 HL) and Group III: Long daylight (LD; 16 HL)]. After 8 weeks, the  excurrent ducts were excised and freed of all adhering connective tissues for gross-morphological and morphometric evaluations. It was found that  compared to the other treatments, the weight and diameter of the epididymis and ductus deferens were significantly increased (P< 0.05) in the fowls  exposed to 16 HL However, no significant (P> 0.05) difference was observed in body weight and length of the excurrent ducts regardless of photoperiod.  Overall, the observed changes in weight and diameter of the epididymis and ductus deferens of sexually- mature helmeted guinea fowl (Numida  meleagris), are thus, a consequence of the photo-stimulatory effects of long photoperiod (16HL) exposure on reproductive activity. These findings could  be useful in designing programs to improve the reproductive efficiency of Numida meleagris.