(2) At present, from the abattoir waste ovaries, each ovary can collect an average of about 10 usable oocytes, after in vitro culture maturation and fertilization of about 4 usable embryos, after the transplantation to the recipient cow, you can ultimately get 1 to 2 calves.
(3) Sperm from cattle, sheep and other domestic animals are often chemically fertilized.
(4) In vitro embryo culture is done to the blastocyst stage and then transferred to the mother.
The answers are:
(1) ③ Sexual? Rapid mass breeding of good breed of cattle to improve economic efficiency?
(2) 10?1 to 2?
(3) Chemistry
(4) Fertilized egg, cleavage stage, mulberry embryo stage, blastocyst stage