Delivery of desired cattle genetics:
Vitrification methods for Bovine in‐vitro produced
embryos to enable direct transfer after warming
Mingyan Yu 1, Bridgit Syombua 2, Charity Muteti 1, Moses Ogugo 1, Steve Kemp 1, Mwai Okeyo 1
1: Animal Biosciences, ILRI; 2: Central Veterinary Laboratories, Department of Veterinary Services
Embryo cryopreservation is important technology that
enables dissemination of desired superior genetics and
the conservation of germplasm.
Unlike the conventional slow freezing method, vitrification
has gained popularity due to the advantages: i)
convenience, ii) low cost and iii) better recovery results.
However, recovery of vitrified embryos normally requires
gradual cryoprotectant dilution in a laboratory setting
before embryo transfer (ET), which significantly restricts
the field application of ET with cryopreserved embryos.
Pictures
This document is licensed for use under a Creative Commons Attribution –Non commercial‐Share Alike 3.0
Unported License June 2012
July 2015
2. In‐straw Dilution (ISD) and Direct Embryo Transfer 1. Solid Surface Vitrification (SSV) and 1‐Step Embryo Transfer
Cumulus–
Oocytes‐Complex
Sperm
IVF 24 hrs
Culture 7 days
Expanded blastocysts
Day 7.5
In‐vitro Fertilization
Vitrification & Recovery
Methods
Two vitrification methods are proposed for bovine in‐vitro produced
embryos which would enable direct embryo transfer after recovery
without use of a microscope or other laboratory equipment. These
methods would therefore simplify the ET procedure to almost that of
artificial insemination with frozen‐thawed semen, thereby enabling
application of ET in remote areas.
The methods will therefore greatly enhance the efficiency of delivery
of desired or improved cattle genetics to the farmers in rural areas
and improve the livestock productivity at scale.
Load embryos Vitrify on solid surface
Insert into
sleeve & Seal
Store
Cut the straw
Preload
the straw
Insert into the
straw
Dilution Medium Vitrification Medium
Embryos
Pre‐load straw
Insert Embryos Seal straw Equilibrate in
LN2 vapour Store
Recover the straw in RT
water Shake to mix Embryos diluted
in straw
Results
Introduction
Methods
Results
ET ET
Method
No. of
Blastocysts
Re‐expansion
Rate (24 hr)
Hatch Rate
(48 hr)
Solid Surface
Vitrification (SSV)
28 (G1) 23 (82%) 16 (57%)
40 (G2) 30 (75%) 16 (40%)
In‐Straw Dilution
(ISD)
21 (G1) 13 (62%) 7 (33%)
54 (G2) 39 (72%) 16 (30%)
Embryos
Advantages
• No need of lab equipment for embryo recovery
• Direct embryo transfer after straw warming
• No contamination through LN2 contact
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