Alleviation of reproductive seasonality in Barki ewes using CIDR-eCG with or without melatonin

Abstract

This study was conducted to evaluate the efficiency of CIDR-eCG protocol with or without melatonin (MEL) on reproductive performance in Barki ewes during non-breeding season. A total of sixty multiparous Barki ewes were divided into two groups, thirty lactating and thirty dry ewes. In each group, animals were allocated randomly into two sub- groups (15 ewes each). In the first sub-group, ewes received a single 18 mg melatonin implant for 42 days followed by controlled internal drug release (CIDR) device for 14 days in conjunction with intramuscular 500 IU equine chorionic gonadotrophin (eCG) at day of CIDR removal. The second sub-group received CIDR combined with eCG in parallel with the first sub group. Melatonin implantation increased (P < 0.05) number of corpora lutea (CLs) and serum glucose concentration, but non-implanted ewes recorded greater (P < 0.05) concentration of estradiol. Regardless of treatment, dry ewes showed lower (P < 0.05) concentration of serum total protein and higher (P < 0.05) concentrations of triiodothyronine (T3) and serum glucose compared to lactating ewes. All ewes exhibited estrus after CIDR removal with greater estrus duration in dry ewes. Prolificacy of melatonin implanted dry ewes was greater (P < 0.05) compared to lactating implanted ewes. In conclusion, Using CIDR-eCG protocol and CIDR-eCG preceded with melatonin successfully induced estrous behavior in anestrus Barki ewes. Melatonin implantation in conjunction with CIDR-eCG protocol enhanced prolificacy in dry ewes during non-breeding season.