III. Embryo In Vitro Production Technology In vitro production of embryos is related to the production of embryos in superovulation. It refers to the fertilization of oocytes and the fertilization of fertilized spermatozoa and their development to morula or blastocyst stage (5~ 7 days) techniques including oocyte in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC). In vitro production of embryos referred to as IVF embryos, currently more than 20 kinds of mammals in vitro fertilization success, including rabbits, rats, humans, cattle, mice, goats, sheep and pigs have produced normal offspring. In vitro fertilization can make great use of the eggs in the ovaries, provide more low-cost embryos, and IVF embryos can be cryopreserved. This technology has broad application prospects in the beef industry. However, the current IVF embryo pregnancy rate is still relatively low, especially after the frozen embryo transfer pregnancy rate is lower, limiting its large-scale application in production.
Antibiotic durg
1.mainly treat for diarrhea, scouring. Especially for yellow ,white or red scour of piglets, paratyphoid fever, bacteroidal scour, infectious gastroenteritis, epidemic diarrhea, dydropsy for the piglets druing ablactation period.
2.Treat for poultry nerotic enteritis,Fowl cholera,Fowl typhoid,paratyphoid,pullorum disease,omphalitis.
3.treat for genital tract infection, such as endometritis, mastitis, breast red and swollen, thermalgia, cotton-like breast milk with blood, too much lochia.
Neomycin Sulfate Powder,Neomycin Sulfate,Neomycin Powder,Neomycin Sulphate Powder Hebei Kexing Pharmaceutical Co., Ltd. , http://www.kexingpharma.com
4. Semen Separation Techniques Semen of livestock contains X and Y spermatozoa, and X spermatozoa has a larger volume and weight than Y spermatozoa. The X and Y chromosome areas of cattle have been determined to be 7.85 square microns and 3.47 square microns, respectively. The DNA content ranged from 2.4% to 4.5%. Therefore, X and Y sperm can be separated based on X, Y sperm DNA content, charge, volume, weight or specific gravity. The main methods are precipitation, density gradient centrifugation, electrophoresis, column chromatography, flow cytometry Separator and HY antigen method.
5. Embryo Gender Identification Techniques Embryonic sex identification refers to the use of certain methods to identify the sex of early embryos (5 to 7 days after fertilization), and then select and transplant embryos of a certain sex as needed.
The main methods of embryo identification are:
1. The cytological method is chromosome karyotyping. The chromosomes of the middle mitosis can be found by fixing, staining and banding analysis, and X or Y chromosomes can be found. The accuracy of this method is almost 100% but it is too time-consuming and the experimental conditions require higher.
2. Immunological methods that use H-Y antigen for embryo sex identification, there are two ways:
(1) Cytotoxicity assay Embryos were cultured on a medium of H-Y antiserum, and embryonic cells with H-Y antigen were lysed and judged as male. This method is actually the execution of male embryos, leaving only female embryos to be transplanted or developed.
(2) Immunological cost analysis The embryos were reacted with H-Y antibody for 30 minutes, then reacted with LgM antibodies labeled with a fluorescent substance, and examined under a fluorescence microscope. Those with fluorescence were judged as male. This method does not require the killing of embryos and can be determined only by taking live tissue from the embryo.
3. PCR method: It is a new method developed in the 1980s. This method first needs to synthesize a pair of primers specific to bovine y-chromosome and then remove a small number of embryonic cells (3 to 5 cells) from the embryo. The PC method was used to amplify bovine male-specific fragments in vitro and observe whether there were specific amplification bands under the UV lamp. If the result was negative, the embryo was judged as male, and if it was negative, it was judged as male.
Six, artificial induced twins technology cattle is a single fetal animal, in the natural state, the cattle's twin rate was 0.5% to 4.5%, such as black and white cows twin rate was 2.4% to 3.4%, Simmental cattle was 5.2 %, Charolais was 6.6%. The use of embryo transfer to induce twins can double the reproductive capacity of a cow, increase the efficiency of cow calving, and reduce the cost per calf, which is of great significance for the development of the beef industry.
Artificially induced cow twins are:
1. Heritability of genetic traits with genetic twins was very low (0.0430.012). Increasing the twinning rate through genetic selection is not only slow but also very difficult. Attempts to increase twinning rates through seed selection have not yet been successful.
2. The induction of exogenous hormones is the use of exogenous gonadotropin to stimulate the follicles of the cow ovaries to produce good and mature ovulation and fertilization. The commonly used gonadotropins are pregnant horse serum gonadotropin (PMSG) and follicle stimulating hormone (FSH). At present, domestic use of inhibin antiserum to immunize cows.
The problem with the use of hormones to achieve twin births is that, under the same low-dose hormones, the ovulatory response of cows varies greatly from one individual to the next, often with one or more embryos in one uterine horn. The side of the cow's uterus is clearly antagonistic to maintaining more than one embryo, while cattle embryos rarely migrate from one uterine horn to the other. In this situation, problems such as miscarriage, dystocia, embryonic death and affecting postpartum lactation levels may occur. So when an ovary sheds two eggs, it can only produce one lice in most cases. Therefore, this method of obtaining twins cannot be used on a large scale in production until a method of controlling each egg in each ovary is found.
3. Embryo Transfer
(1) Artificial insemination combined with embryo transfer means that a cane embryo is transplanted in the opposite uterine horn of the corpus luteum at the time of cow estrus mating to achieve the purpose of twinning.
(2) Transplanting two sticks of embryos means that one cane embryo is transplanted into the two uterine horns of cows 6 to 7 days after estrus. This is the best way to obtain twins. When each uterine horn was transplanted with a fertilized egg, 72% of the cows were conceived, and 73% of them produced twins. The fertility rate and the natural fertility rate were the same, but the calves were nearly 73% more likely than the natural fertilization. This greatly increases the productivity of the cows.