Effects of exogenous melatonin on sperm cellular parameters of sexually-matured helmeted guinea fowl (Numida meleagris) subjected to varying photoperiods.

Introduction: Photoperiodic treatments have been of practical interest in controlling seasonality of reproduction in poultry. Melatonin is responsible for transmission of important photoperiodic signals that regulate reproduction. However, there are limited research on the effect of photic (artificial light) stimulation and melatonin on the sperm cellular characteristics in avian reproduction. Therefore, the present study was conducted to determine, the effect of combined influence of varying photoperiodic treatments and exogenous melatonin (Mel) administration on sperm parameters in helmeted guinea fowl (Numida meleagris). Method: A total of forty-two (42) sexually-matured helmeted guinea fowls were randomly assigned into six (6) photoperiodic regimes; [Group I: short daylight (SD; 8 HL (hour of light (HL) Group II: SD+1mg/kg Mel; 8 HL+ Mel), Group III: regular daylight (RD; 12 HL), Group IV: (RD+1mg/kg; 12 HL+ Mel), Group V: long daylight (LD; 16 HL) and Group VI: (LD+1mg/kg; 16 HL+Mel)] of seven birds (n=7) per group. After 60 days of experimentation, assessment of spermatozoa morphology, motility, concentration and sperm cell live-dead ratio was done. Results: Microscopic evidence revealed that percentage sperm abnormalities were significantly reduced in 16HL +Mel group, compared to other treatment groups. Conversely, the spermatozoa concentration, motility and live-dead ratio were significantly higher (p <0.05) in guinea fowl exposed to 16 HL and exogenously treated with Mel, compared to other groups. Significance: The findings of this study has shown that long photoperiod (16HL) and exogenous melatonin administration remarkably influence the sperm parameters in the exposed helmeted guinea fowl. Hence, guinea fowl breeders could optimize the semen output by the approach regardless of the season. [ABSTRACT FROM AUTHOR]