Yes, there are many bad aspects about genetically engineered animals, but there are even more better aspects about it. If the FDA approves and regulates genetically engineering animals, then it should be alright. There is no sense in fighting something that will ultimately start being the new normal. If it is cheaper, more efficient, and doesn't hurt the animals, than obviously major GE companies will do it. There is not really anything people can do to fight it. Everyone should accept it even if they don't like it.
The benefits of genetically engineering cows is that they produce more milk, for salmon it's that they grow much faster. These components completely outweigh the drawbacks of eggs dying before birth, or any other small defects. If the egg is not really alive yet, then there should be no issues. Also, it seems that it would be better for the environment, for example, cows can be genetically engineered to release less matter out of there bowels. That would be really good if all cows did that, because the methane coming out of cows is really bad for the environment. Some people just need to get over there ethical issues with GE animals, and accept the new generation of genetical engineering.