Effect of melatonin administration on conception rate and biochemical properties of the epididymis in West African Dwarf (WAD) ewes and rams, respectively in dry season

Abstract

The effect of melatonin administration on conception rate and biochemical properties of the epididymis in West African Dwarf (WAD) ewes and ram respectively were investigated in an experiment with twenty-four sheep (16 ewes and 8 rams) aged, 12 - 18 months, with average weight of 16.5 ± 2kg. Animals were randomly allotted to four treatment groups, each group consisting of six animals and varied doses of melatonin were administered for 30 days. Melatonin was administered at 0mg (T1, control), 5mg (T2), 10mg (T3) and 15mg(T4) to each group, which contained 4 ewes and 2 rams for 30 consecutive days. Twenty-five percent (25%) and fifty percent (50%) conception rate were observed in ewes that received 10 mg and 15 mg of melatonin, respectively. One fetus was obtained from a single ewe in those administered 10mg melatonin, while two fetuses from two ewes , were obtained from those on 15 mg melatonin. Lactate dehydrogenase, was significantly (P<0.05) higher in rams administered 15mg (917.50iu/L) than those on 0mg, 5mg and 10mg melatonin respectively. Lactate dehydrogenase of rams on 5mg, and 10mg (435.50iu/L and 655.50iu/L, respectively) melatonin treatment were significantly (P<0.05) higher than those in control group (375.50iu/L). Total cholesterol was significantly (P<0.05) higher in rams receiving 0mg, 5mg and 10mg melatonin than those that received 15mg melatonin treatment. Glucose was significantly (P<0.05) higher on animals that received 10mg (17.00mg/dL) melatonin compared to those on 0mg (12.00mg/dL), 5mg(12.50mg/dL) and 15mg(11.65mg/dL). Zinc was significantly (P<0.05) higher in animals administered 10mg and 15mg melatonin, however both were significantly different from animals on 0mg, and 5mg melatonin. The paired epididymis, sperm reserves of rams on 15mg (21.50 X 10⁶ cell/mL) melatonin treatment was significantly (P<0.05) higher than those on 0mg (11.20±1.36), 5mg (6.47±1.36), and 10mg (0.90±1.36). No Significant difference was observed in Total Protein, Sodium, Potassium, Chloride, Magnesium and calcium in all the treatment groups. In conclusion exogenous melatonin influenced the conception rate of ewes and improved the quality of epididymal sperm cells of the rams in the dry season.

Keywords: Melatonin; epididymal biochemical properties; sperm reserves; West African Dwarf sheep; Dry season