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Discussion Starter · #1 ·
In our litter there were two black Irish marked, a blue Irish marked and five of these mystery colors (three Berkshire, one Irish, one self). They are agouti but beyond that are they blue agouti or maybe cinnamon? All have black eyes.
 

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possibly blue agouti or blue cinnamon. It won't be really obvious until they get there adult coat through as it's all fluff right now and that doesn't really show the colour well.
 

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Discussion Starter · #3 ·
Another color related question. In this litter are two black Irish marked boys. One is very black even his tail is slightly darker and the other seems faded, but the interesting thing is the darker one even developed his color earlier for quite a while I thought the lighter black boy was going to be dark grey or something. My question is since all other things are equal what would cause two black rats from the same litter to be slightly different colors?
 

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Discussion Starter · #6 ·
I've noticed in looking at photos on line there can be a big difference in rats who are gentically the same color, maybe due to carrying dilute genes? It's been a long time since I raised a litter but I used to have a small caviary, and guinea pigs certainly come in a lot of colors but they tend to express pretty consistently! Golden agouti is the same no matter what they carry! Only exception I have seen is in the reds and creams, which I didn't breed but saw in shows, had many shades from nearly white to a deep red. Rat genetics seems very complicated in comparison!
 

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Shades on babies can be caused by a number of things, some is developement e.g. if a rat is slightly behind in terms of growing up (kind of like a runt, but not always a true runt, just not as strong as the others) then there colour lags behind the other rats, often by up to 2 or 3 days. Another is recessives, these are genes that they are carrying but not expressing. A good example of this is the red eyed dilute gene, when you have 2 copies of it the rat looks either buff (beige) or topaz (fawn) or some variation of the colour, however if you've only got one copy it actually slightly lightens the shade, so a black rat will be a paler black than one not carrying the gene, the agoutis are also warmer and brighter (some agouti breeders add it in as RED carrying agoutis often show better). This is a fairly extreme reaction for a carried recessive (it was so obvious in one of my litters that i managed to predict which agoutis carried RED and which didnt from a few days after birth) but other recessives do lighten the colours as well. I remember meeting some black essexes that carried so many hidden recessives that they were closer to a blue rat than true black.

You aslo get other genetic factors, these arent as easy to define or track, its why selective breeding works, the genetic relationship isnt simple but if you select for blacker rats then over years you will get gradually darker black rats.

Then theres dietry factors, diet, especially things like protien and copper, really affects how the coat produces its colour. It doesnt affect nursking kittens so much (unless mums under nourished) but it can hit them later on in life. Some rats fed an inappropriate diet loose loads of colour, there owner thinks they've discovered a rare variety such as chimera, feeds them well and a month later there rat is actually mink or agouti or similar.
 
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