Incidence and avoidance of zona fracture in cryopreserved bovine ova and embryos

Authors: Mohanan M, Subramaniam A, Devarajan KP
Publication: New Zealand Veterinary Journal, Volume 38, Issue 4, pp 156-157, Dec 1990
Publisher: Taylor and Francis

Animal type: Livestock
Subject Terms: Reproduction - female, Reproduction, Reproduction - assisted/embryo transfer, Embryo/fetus, Disease/defect
Article class: Scientific Article

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Abstract: Ova (n=62), which were collected from slaughterhouse bovine ovaries, and embryos (n=26), which were non-surgically recovered from 11 superovulated crossbred donor cows, were frozen. The frozen ova and embryos were then thawed using two conventional thawing protocols, i.e. at 37°C for 30 seconds in a water bath and at 25°C for 2 minutes in air. Some 64.5% of the ova and 53.8% of the embryos thawed in the water bath and 16.1% of the ova and 7.7% of the embryos thawed in ambient air exhibited fractured zonae pellucidae. The slow thawing protocol had a lower incidence of zona damage in cryopreserved oval and embryos than the fast thawing protocol. A low pregnancy rate (12.5%) was recorded for embryos transferred with zona fracture while embryos transferred with intact zonae had a rate of 35.3%) indicating that embryos with zona damage are less viable.

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