Effect of adding aqueous extract of Melissa officinalis leaves and some other antioxidants to milk–based extender on post-cooling and post- cryopreservative sperm’s individual motility and live sperm percentage of Holstein bulls

Abstract

This study was conducted to explore the effect of adding aqueous extract of Melissa officinalis leaves (AEMOL), some antioxidants and their combinations to the milk-based extenderfor increase on sperm's cells individual motility percentage on and live sperms percentage semen for Holstein bulls following different preservation periods. The study was executed at the Department of Artificial Insemination, Abu-Ghraib belong to the Directorate of Animal Resource, Ministry of Agriculture, during the period from October 2015 to February 2016 using ten Holstein bulls of 2.5-3 years old. Semen was collected via artificial vagina in one ejaculate per bull per week for the 7-week experimental period. Pooled semen was equally divided into ten groups within one experiment. In this experiment, AEMOL (0.062mg/100 ml; A2), WEMOL (0.031 mM) + 5 mM of vitamin C (A3), AEMOL (0.062mg/100 ml + 0.08 mM of Trolox (A4),AEMOL (0.062mg/100 ml + 100 IU of catalase (A5),100 IU of catalase (A6), 5 mM of vitamin C (A7), 0.08 mM of Trolox (A8), 0.2 mM of vitamin E (A9) and AEMOL (0.062mg/100 ml +0.2 mM of vitamin E (A10). The effect of these additives on semen characteristics of Holstein bulls for different preservation periods (cooling at 5◦C, 48 hrs., 1, 2 and 3 months post cryopreservation, PC) were studied. The A2 group exhibited greater (P≤ 0.01) sperm's cell individual motility, live sperm percentage, as compared with A1 group at all preservation periods. Greater sperm's cells individual motility, live sperm percentage noticed in A4 group in comparison with the A1 group at all preservation time periods. On the other hand, A5 group exhibited greater (P≤ 0.01) sperm's cell individual motility, live sperm percentage, as well as, adding of vitamin E alone (A9) or combined with AEMOL (A10) to milk-based extender had a positive (P≤ 0.01) effect in improving sperm's cell individual motility and live sperm percentage at all preservation time periods. In conclusion, adding of AEMOL as alone or combined with the other synthetic antioxidants to milk-based extenders had a crucial role in improving PC sperm's cell individual motility and live sperm percentage of Holstein bulls. This was reflected positively on increasing pregnancy rates of the inseminated cows.