Acta Veterinaria et Zootechnica Sinica ›› 2025, Vol. 56 ›› Issue (12): 6180-6190.doi: 10.11843/j.issn.0366-6964.2025.12.021

• ANIMAL BIOTECHNOLOGY AND REPRODUCTION • Previous Articles     Next Articles

Optimization of in Vivo Porcine Embryo Vitrification Protocol for Rongchang Pigs

ZHANG Liang1, XU Jiehuan2, ZHANG Fengming1, TU Zhi1, WANG Qing3, ZHANG Lidan3, ZHANG Keqin3, HUANG Cong3, DAI Jianjun2*, PAN Hongmei1*   

  1. 1. Chongqing Academy of Animal Sciences, Chongqing 402460, China;
    2. Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Institute of Animal Husbandry and Veterinary Science, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China;
    3. National Center of Technology for Pigs, Chongqing 402460, China
  • Received:2025-05-07 Published:2025-12-24

Abstract: This study aimed to optimize the in vivo embryo cryopreservation method for Rongchang pigs to improve the hatching rate of blastocysts after embryo freezing. The experiment used 50 Rongchang pigs to obtain in vivo embryos through synchronized estrus, artificial insemination, and surgical flushing. The effects of different cryo-carriers (SOPS and Cryotop), different vitrification cryoprotectants (Medium-199, NCSU23 and TL-PVA), lipid centrifugal polarization in pre-cryopreserved morula and zona pellucida (ZP) digestion of vitrified-warmed (V-W) embryos were compared, and the survival rate, continued development ability and blastocyst cell number of V-W embryos were determined to screen the optimal embryo V-W method in Rongchang pig. An average of 9.22 blastocysts per donator were obtained after embryo flushing, that raised to 12.16 blastocysts per donator combining with in vitro culture. The survival and development rate of V-W embryos using Cryotop were significantly higher than those of SOPS (P<0.05). V-W embryos of NCSU23 group gained the highest survival rate (85.91%±3.27%) and development rate (80.61%±10.06%) comparing to Medium-199 and TL-PVA groups. The abilities of embryonic cell division were NCSU23>Medium-199>TL-PVA. This study proofed that NCSU23 was the most suitable cryoprotectant for Rongchang pig embryos. Lipids in morula were polarized by centrifugation before vitrification, while post-V-W embryonic development was not observed. The time cost of ZP digestion was prolonged after V-W, ZP hardening affected the expansion and hatching of V-W embryo, while ZP digestion offset this disadvantage and promoted the expansion of V-W embryo. In vivo embryo production combining with in vitro culture raised the efficiency to 12.16 blastocysts per donator. V-W embryos using Cryotop and NCSU23 reached the highest survival rate (85.91%±3.27%) and expansion and hatching blastocyst rate (80.61%±10.06%) and the highest level of embryonic cell division. The ZP digestion promoted V-W embryo expansion after warming.

Key words: in vivo embryo production, embryo freezing, Rongchang pig, cryoprotectant, zona pellucida hardening

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