Gene knockout is when the BLG gene would be removed from the DNA and replaced with a non-functional version of the gene, meaning that the messenger RNA of the gene would not be produced. This could be dangerous for the cow as the messenger RNA of many different genes work together for different functions. If the mRNA of the BLG gene is taken out, the effect that it has on the expression of other genes is unknown.
However, by using gene knockdown, the BLG gene still produces the messenger RNA (but it is inactivated by siRNA, so the BLG protein is not produced) which means that there is no effect on the expression of other genes. This is why gene knockdown is used instead of gene knockout.

To silence the BGL gene, (and prevent the protein from being synthesized) dsRNA would be inserted into the DNA of an udder cell of a cow. The BLG protein is produced in the udder cells of a cow. To produce milk from the cow without the BLG protein in it, the technique of gene knockdown is used. During gene knockdown, two processes called transcription and translation occur.

Transcription occurs in the nucleus, and it is when the BLG gene’s sequence of DNA is …show more content…
The blastocyst is left to develop for a few days in conditions that mimic the uterus of a cow, and then the blastocyst is implanted into the cow who is chosen to carry the developing embryo. The pregnancy is then treated as normal, and after the gestation period of 283 days, a calf is born that is an exact copy, or clone, of the cow that the udder cell came from. It is an exact copy of the cow that the udder cell came from, and not an exact copy of the egg donor cow. This is because during the process of SCNT, the DNA of the egg cell is removed, and replaced with the DNA of the udder cell, therefore all of the DNA is from the udder cell donor, resulting in the embryo being almost genetically identical to the udder cell