Effect of partial oocyte maturation before ovum pick up on developmental competence of buffalo oocytes

• Amjad Riaz Department of Theriogenology. Pakistán
• Muhammad K. Ashraf Department of Theriogenology. Parkistán
• Talha Ashraf Department of Theriogenology. Pakistán
• Ali Husnain Department of Theriogenology. Pakistán
• Muhammad Yaseen Department of Theriogenology. Pakistán
• Muhammad H. Mushtaq Department of Epidemiology & Public Health, University of Veterinary and Animal Sciences, Lahore, Pakistan.
• Burhan E. Azam Livestock Experimental Station Bhunikey, Buffalo Research Institute, Pattoki, Pakistan

DOI: https://doi.org/10.52973/rcfcv-wbc120

Keywords: buffalo, ovum pick up, in vivo maturation, hCG, cleavage

Abstract

Compared with in vivo matured oocytes, in vitro maturation produces half the number of blastocysts in cattle. We hypothesized that partial maturation of oocytes in vivo improves blastocyst formation in buffalo. Therefore, we aimed to investigate the effect of partial in vivo maturation on in vitro embryo production (IVEP). The estrous cycle of buffalo was synchronized by double shot prostaglandin (PGF2α, Fatro, Ozzano Emilia, Italy) with 11-day intervals. On the last PGF2α, dominant follicle ablation and supplementation of progesterone by inserting intra- vaginal controlled internal drug release was performed to synchronize the follicle wave emergence and considered as Day 0 of the experiment. Starting on Day 2 of the experiment, the ovaries of buffalo were super- stimulated with six equally divided doses of 33.3 mg per dose of porcine follicle stimulating hormone (Vetoquinol, Magny-Vernois, France) i.m., for three days with 12 h interval. The experiment was randomized, with a complete block design. On Day 5 of the experiment, buffaloes were blocked by parity, and within the block, they were assigned randomly to receive 1500 IU of human chorionic gonadotropin i.m., (hCG, LG Chem, Seoul, South Korea; n = 6) or to remain untreated control (CON; n = 4). Oocytes were aspirated six hours after treatment implementations using ultrasound-guided Ovum Pick Up (OPU). The data was analyzed by using mixed effect models in SAS statistical software. Treatment with hCG did not affect the number of small, medium, and large follicles at the time of OPU. However, hCG treatment increased (p< 0.01) cleaved oocytes compared with CON (84.0 vs. 40.5 ± 7.2%). Similarly, oocytes treated with hCG had greater (p = 0.04) development from cultured oocytes to Day 7 embryo (52.5 vs. 18.1 ± 10.3%). Treatment with hCG did not affect the development of cleaved oocytes to Day 7 embryo. In conclusion, our results indicated that partial oocyte maturation improved the in vitro embryo production. However, the impact was pronounced at the cleavage rate rather than in the later stages of embryo development.