What often annoys me about animal experiments

I've just read a study about conversion of ALA to DHA via the liver on rats. The results were that it appeared they easily made enough. Now how does that correlate to humans...well it doesn't! You'd have to repeat a version of the experiment on humans to see if it has any validity, therefore the animal experiment is essentially useless as a predictor as there are way too many variables. The sad thing is there are already people who do not eat DHA at all & so you could very easily insure an adequate ALA source & measure the rates of DHA directly in humans, therefore proving your theory. Studies like these on animals are a total waste of cash, sure it would cost more to do a study on humans, but all this study proves is that rats can convert enough ALA into DHA...NOTHING ELSE!
We need as many studies as possible that can be done on humans to be done on humans. Especially one's like this where there are already populations living the lifestyle the researchers are trying to mimic, it's crazy not to make use of these populations & see what the results are!
It's so annoying

I read a bunch of stuff on whether or not all the decades of experiments having rats inhale fumes/aerosols was of any use and it seemed like people just really didn't want to admit it had been huge waste of time and money.

I've heard that the primary goal of animal testing is to provide legal defense to drug and cosmetic companies if they are ever facing charges for harm their products do.
"We tested our product extensively on animals, and they were not harmed..."

of course animals could not complain if anything wrong happens during experimentation. Its difficult to take the consent of humans for any experiment even if they are already using that product.