Question on possible holdbacks? DUW

I am still so new to the world of breeding my feeder rodents and with talk of genetic issues I figured I would ask some more knowledgeable than myself.
Here are several that I would like to hold back. Parents are all very healthy, friendly and yes part of it is how they look. However, I know that some color/patterns have more issues than others. Colors are as close to actual as I could get.

https://ball-pythons.net/gallery/fil...5/Dscn2109.jpg

https://ball-pythons.net/gallery/fil...5/Dscn2101.jpg

https://ball-pythons.net/gallery/fil...5/Dscn2099.jpg

https://ball-pythons.net/gallery/fil...5/Dscn2081.jpg

https://ball-pythons.net/gallery/fil...5/Dscn2074.jpg

https://ball-pythons.net/gallery/fil...5/Dscn2066.jpg

Don't hold back the rats with headspots, blazes, etc. I wouldn't hold back american blues either, they tend to have weaker immune systems(IME).

The selves, hoodeds, berkshires, irishes(spot on chest or belly), barebacks(no headspots) are ok to use for breeding.

So, the rats in pictures 1,2,3,4, and 6, I wouldn't hold back. I would recommend getting breeders that are solid colored or hooded, so you don't have to worry about possible genetic disorders and temperment problems(blues tend to be neurotic and not good parents, along with the bad immune system).

Just some food for thought.

Of course, all my favorites. #3 looks just like her mom and has her personality. Her mom is my favorite rattie, is the most friendly of all my rats. I guess I will start looking at the solid black and agouti's to hold back instead. Hopefully at some point blues will be bred with better health and temperments, they are by far my favorite.

My blue self is a great mom, with no issues, but she's a steel blue (or I believe a Russian blue).

At one point I had three blue hoodeds like the one in your first picture. One never got to breeding weight and I was at the vet 2 x a week getting it treated for a RI and an inner ear infection. She lost her battle, sadly.

The second one died while in labor with her second litter and the third had her second litter and looked miserable while giving birth and wasn't removing the placentas from the babies. I got the babies all cleaned up myself and fostered them off, as she showed no interest in them (this was her second litter, she was a great mom to her first litter)

She's now a companion female for my resting females and hold back females when she doesn't have resting females with her, as I don't think she was a "bad" mother, she just isn't fit for breeding . I won't ever breed blue hoodeds again.

I had only one of the very light blue rats, a male, who was not only infertile he was mean as could be and almost killed another of my male rats. Needless to say he made a quick exit from the colony. I have a blue self male now but he's the dark, steel blue rather than that lighter almost powder blue.

Most of my rats are american blue or blue carriers and I have had none of those issues. They have been outcrossed several times to non-blues from other bloodlines which may have helped.

I haven't actually bred any blue to blue yet, it's always been blue carriers (hets) producing blues and when the blues are bred they are usually bred to non-blues.

I dont think that mega colon is directly linked to american blue. It is said that the Blues in america are healthier than the ones in britian. Also, the reason most blues are nuerotic are ususally from excessive inbreeding. (from what i've heard)

Mega colon can only be eliminated by that very same excessive in/line breeding. But when those rats are outcrossed with another rat, the mega colon will return once again. There is alot of controversy in the fancy as to the white spotting gene, "s/s" If the effects are dominant or recessive. Some people claim that if it were dominant, that nature would take care of itself. This is highly disputed, since it is still around and doesnt appear in every generation.

Roan/husky is created by the spotting gene, that is also where you will see the blazes most commonly. A poor roan/husky will look like a berkshire, but berkshire is created by at least two different alleles and their modifiers.

Any head spots and variegated are also linked to it, as it's a "sorta modified" spotting gene. Also, the chinchilla color is almost always accompanied by the blaze and is in part created by the white spotting gene. (Don't worry, chinchilla is pretty rare to find because of that fact)

[All that I mentioned is still under scrutiny in the fancy, but that is what I have absorbed when it comes to marked rats.]

What I'm trying to say is, most of your rats carry some sign of the white spotting gene. If any of those rats have any occurance of megacolon, I would not breed their parents again, or rather, I would absolutely not hold back any of their offspring under any circumstances. If you feed off at the weanling mark, you may get away with a few more litters for feeding purposes only.