Cryosurvival and pregnancy rates: One‐step protocol for freezing–thawing Shangri‐la Yak (Bos grunniens) Embryos

Abstract

The yak is one of the most important and economically useful animals for highlanders. The decline in the yak population requires effective measures for the conservation and multiplication of elite germplasm. A standardized protocol will simplify the freezing and warming of yak embryos in straw and facilitate embryo transfer. In this work, we investigated a one-step protocol that uses a stable basal medium, which comprised a warming medium (1.08 M sucrose) and a freezing medium (EFS40). We also assessed the effects of the new transfer method on embryo survival. A total of 145 yak frozen embryos were thawed in a standard medium system. The one-step protocol led to a high recovery percentage (84.93) of yak embryos that survived vitrification and warming. The in vitro survival rates of these embryos significantly different from those of embryos frozen-thawed via the conventional method. The 95 embryos frozen-thawed via our one-step protocol were then implanted in selected recipients. Thirty-six singleton pregnancies were established. In conclusion, the proposed one-step method is a simple, safe, and standardized freezing-thawing protocol that ensures embryo survival and quality under field conditions. This study establishes new possibilities for the widespread use of embryo transfer in yaks.

Comparison of Gut Microbiota of Yaks From Different Geographical Regions

“…The temperature here is markedly different between the day and nigh, and the day is long. Yaks also live in regions with hypoxia and sparse vegetation ( Jia et al, 2018 ). Yushu (Qinghai Province) is located in the eastern part of the Qinghai-Tibet Plateau, where yaks live in areas with low oxygen partial pressure, large temperature differences between the day and night, intense radiation, and short grass growing period ( Qin et al, 2019 ).…”