Improved in vitro development of OPU-derived bovine (Bos taurus) embryos by group culture with agarose-embedded helper embryos

Abstract

The average number of oocytes collected by ovum pick up (OPU) from Bos taurus cattle is <8 per live donor The objective was to determine whether development of small numbers of cattle embryos (produced by OPU and IVF) was enhanced by including 'helper embryos, produced from abbatoir-derived oocytes and embedded in agarose Oocytes were from abbatoir-derived ovaries (Experiments 1 and 2) or OPU of elite donors (Experiment 3) In Experiment 1 cleaved embryos (2-8 cells), were randomly allocated Controls were groups of 1, 3, 5, 10, and 20 cleaved embryos cultured in 50 mu L serum-free SOF, whereas treatments were groups of 1, 3, and 5 embryos freely cultured along with helpers in groups of either 9, 7 or 5 embedded in agarose per droplet Therefore, there were 10 cleaved embryos per droplet in combinations of 1 + 9, 3 + 7 or 5 + 5 (free + helper), respectively There was an increase in the progression to blastocyst for 1-5 embryos per droplet, compared to 10 and 20 (6 6-24 2% vs 39 2-43 3% P < 0 05) For the tested free embryos those cultured with helpers had increased blastocyst development over their control counterparts (39 3-49 5% vs 6 6-24 2%, P < 0 05) When the number of embryos per droplet was 10 or 20 blastocyst percentage was similar (39 2-49 5%, P > 0 05) In Experiment 2 addition of an agarose chip to the culture medium did not significantly affect development to the blastocyst stage In Experiment 3 after fertilizing OPU oocytes with sorted X sperm, a group of three cleaved embryos were cultured in a droplet with either seven helpers (3 + 7) or alone (3 + 0) Blastocyst development of OPU oocytes in the 3 + 7 group was 37 1%, higher than that in the 3 + 0 group (11 8% P < 0 05) In conclusion, limited numbers of OPU/IVF oocytes had competent development when cultured with helpers (embedded in agarose to provide physical separation) (C) 2010 Elsevier Inc All rights reserved