Those barns and houses are all prefab and if the animals died shortly after they arrived why would they need to build barns anyway?

Like Sulu and Kelowitz found, the barns were designed and built just for storage. Which would indicate that the animals were already dead or dying before the buildings were begun. Prefab or not, that's pretty hard to swallow that the people would still be alive and well enough to plan and build and complete all the barns etc, before themselves dying. And why would they have PREFAB building stuff for buildings NOT housing animals, if they didn't know about Berthold rays yet?

Well it depends on how many colonist were send down and how many have died by Berthold rays.

From what Spock said, the colonists would have begun dying after about a week. And it's not that I'm talking about that they did survive, etc. My original point was that nobody expressed any surprise about all the completed buildings and fences and all the rest, when they first beamed down, when it was evidently known that the colonists wouldn't have survived much longer than ONE WEEK. We know/find out what really happened, because of the spores. But at the start, I found it odd that Kirk et al didn't seem to think there was anything odd about finding all those buildings etc.

Of course the "real reason" was they were using a set that had been built for something else.

Well if you already knew the answer why did you ask the question?

But the "real reason" is exactly why there should have been some mention of its oddness.

Like I said many times before don't focus too much on the science and credibility but on the stories

The blonde could be Jeannie Malone. Apparently she was a stand in for Grace Lee Whitney but appeared as background characters through all 3 seasons. She can be seen climbing in to the transporter after the “this is mutiny, mister” scene but she is in the back shadows there too.

@Rudd-12 said:

The blonde could be Jeannie Malone. Apparently she was a stand in for Grace Lee Whitney but appeared as background characters through all 3 seasons. She can be seen climbing in to the transporter after the “this is mutiny, mister” scene but she is in the back shadows there too.

There are pictures of her at Memory-Alpha.

yeah, there is just not a very clear shot of her face in this episode and she was made up heavily and with very different hairstyles throughout episodes.

That is usually the case with these background extras.I am surprised that you actually was able to find out who she was.

It's incredible that she was an extra (uncredited) in 37 episodes and a stand-in in 66 episodes.

Last known appearance was in "Greencastle (2012)".

Is she still around?

According IMDB she is still around

IMDB doesn't provide any biographical information. The last update is from 2012.

Well they haven't mentioned she had died on any other outlet so we must assume she is probably still around.