Applying Technology On Cow And Sheep Embryo Transfer And Analysis On The Factors Of Effecting Available Recipient Rate And Pregnancy Rate

Applying embryos transfer technology to introduce new varieties of cows and sheep.The item introduced 3980 embryos of cows and sheep,transferred 3909 recipients in 43 places,given birth to 1931 cows and sheep.Analysis on the factors of effecting the available recipient rate and pregnancy rate of cow or sheep embryos transferred,and estrus synchronization of sheep to establish a highly efficient ET svstem.In the experiment,of the 800 cows selected at random for estrus synchronization.600 served as ET recipients.And 705 sheep were selected for estrus synchromzation followed by transfer of frozen-thawed embryos into 460 recipients.The results of the experiment indicated:The rate of available recipients and pregnancy rate in Simental cross-bred(multipariry cows(1-3 parity)/cows of 2～6 years)was higher than the local cattle cress-bred and Holsteins(nulliparity cows/the recipient cows(≥7 years or＜2 years),but they showed no significant difference(P＞0.05)between groups.The rate of available recipients of 1～3-parity cows was higher(P＜0.05)than that of≥4-parity cows.No significant difference(P＞0.05)in the rate of available recipients and pregnancy rate was observed in the cows of good condition and medium.The rate of available recipients treated for estrus synchronization with CIDR when ovum was in luteal stage was higher(P＜0.01)than that in follicular stage.Whether CIDR was inserted into reciptent vagina or not after ET had no great effect on ET pregnancy rate(P＞0.05).The pregnancy rate of double embryo transferred was higher(P＞0.05)than that of single one. Early blastocvst had the highest pregnancy rate in ET.the second was morula,and the last was blastocyst;no significance(P＞0.05)was observed between groups.The pregnancy rate of embryo transferred into left-side uterus horn was higher(P＜0.05)than that of right-side one.Pregnancy rate of recipient sheep with 2 CLs on single side was higher (P＞0.05)than with 1.No significant difference(P＞0.05)was observed in the pregnancy rate of embryo transferred surgically or by laparoscope and the estrus rate of sheep treated with CIDR or Progestagen Sponge did not differ(P＞0.05).