Rat Growth – One to Two Weeks Old

This post tracks the growth Blink and Otter’s 13 babies during their second week (you can read about their first week here).

The babies have grown quite a bit more hair in just 24 hours and now have super shiny, velvety coats. They also have fingernails! I’m pretty confident there are 4 boys (2 hoods, a black berkshire, and a dilute) and 9 girls (5 black berkshires, 2 hoods, and 2 dilutes) in the litter.

It’s getting easy to tell the babies apart. The berkshires have slightly different amounts of white on the tips of their tails and their ‘socks’ reach different points on their legs. The dilutes are changing colour, one is a hood one of the others is a darker berksire (possibly mink?) and the other is quite light (dove?). The hods of course are easy as they all have different patches down their backs. One little boy even has a teeny tiny head spot!

The babies have been getting more and more mobile throughout their second week. They don’t pull themselves around on their tummies now, instead they ‘walk’ slowly and haltingly like little zombies. They have also started claening themselves which is super cute to see.

Some of the little ones have started venturing out of the next in their cage but are very quickly put back by their mother. They are starting to look much more like little rats now, their eyes are less bulgy, their ears are not so stuck down to their heads, and they have lots of fur.

Today is the day the babies ear canals drained allowing them to hear. They are moving around a lot when I get them out and will crawl to wherever I put my hands and squish themselves up against them. Their mother no longer frets when I get them out and sometimes comes out with the other girls when they are out of their cage. She’s excited, and a little bit pushy with them, but I think when the babies are grown there will be no problem moving her back in with her friends.

One of the babies has one eye open! They are all getting quite quick at crawling around and are starting to hop and jump a bit too. They wear themselves out quickly though and after scurrying round for a few minutes they quickly find some friends to pile up and sleep with.

All the babies now have their eyes open. Their fur is less like velvet and more like normal rat fur, although they don’t have guard hairs yet. It’s easy to see the different markings on the berkshires tummies and I’m confident that there are 4 boys and 9 girls in the litter.

Marking Genetics

I’ve found it quite hard to find information on rat genetics that’s relevant to New Zealand. We have a very limited number of colours and markings compared to other countries due to import laws so often the information online is confusing as it talks about genes that we don’t have here. The genetics of the three most common marking types – self, berkshire, and hooded – is straight forward though.

A self rat (HH) has no distinct white markings. Often their undersides are a lighter shade than their backs but they are basically all one colour. Berkshire rats (Hh) have white paws, white makings on their undersides, and they usually have white tail tips. Hooded rats (hh) have a coloured head and shoulders and a coloured stripe or blotches down their spine but the rest of their body is white. If a self is breed to a self they should produce get 100% self babies. Similarly, two hooded rats together should produce a whole litter of hooded babies. Two berkshire parents however should produce 25% self, 25% hood, and 50% berkshire. Punnett squares for these three crosses look like this:

There are three other pairings possible: hooded and berkshire, hooded and self, and self and berkshire. A hooded rat paired with a berkshire should produce 50% berkshire and 50% hooded babies,  a hood and a self should produce a full litter of berkshires, and a berkshire and a self should produce 50% self and 50% berkshire babies. The Punnett squares look like this:

 

It’s not really that simple, and more in depth research suggests that the genetics denoting markings are not as pure as as they would seem from the Punnett squares, but they serve as a good estimate for what will come out of a pairing.

 

 

Rat Growth – Newborn to One Week Old

This post will track the growth Blink and Otter’s 13 babies during their first week (you can read about their second week here). They were born on the 9th of February, one day after their due date, after an uneventful pregnancy. All were born alive and of similar size and weight, although one of the berkshires is very slightly smaller than the others.

The babies were born during the day on the 9th of February. Here they are just a few hours old (sorry for the gross bedding). They are completely colourless and hairless except for the tiniest whiskers. Their ears are just flaps of skin stuck down to their heads and their paws are webbed nubs. They can squeak quite loudly and do so wherever their mother comes to feed them.

At two days old some of the babies already have pigment. The this stage it looks like there are 4 black hoods, 5 black berkshire, and 4 that could be mink as they haven’t developed any colouring. This is a happy surprise as, while I knew the mother was carrying mink, I didn’t think the father was. Assuming the lighter babies are mink, both parents must be dilute carriers (aaMm).

At three days old the babies have darkened up a bit more and it’s looking like the little one is also a black berkshire, not a dilute like I first thought, it just took a little while for the pigment to come in. The babies have limited movement though they can pull themselves along and roll over if they get flipped onto their backs. Blink has moved them from her nest in the corner to the rody house.

Apart from a bit of weight gain, there wasn’t much change between the day 3 babies and the day 4 ones. They are still hairless, blind, and deaf. The skin on their undersides is slightly translucent and you can see the milk inside them after they have had a feed. Blink leaves them uncovered on the plastic base of the igloo and uses the bedding to stuff the entrance hole, but not to cover the babies.

The black babies have darkened up lots over the last 24 hours but it’s still impossible to tell what colour the lighter ones are going to be. Their whiskers have grown longer and then have a very very fine coat of tiny hairs. Their weight has also more than doubled – from about 3 grams when they were a day old to more than 7 grams for the chubbiest ones. The little one black berkshire seems to be about a day behind the others in terms of growth and is still quite a lot paler and has just hit 6 grams.

The babies seem a lot more mobile today. They get handled two or three times per day (for less than 5 minutes) and sometimes they don’t even wake up. Today though, a couple of the bigger ones pulled themselves  around on their tummies quite speedily and I had to to scoop one up in a hurry as it was about to scoot off the bed! Their mother is eating A LOT, more than my other 3 girls combined, and the babies are growing well.

The babies are a week old. They now have a very fine velvety coat and are all quite mobile. They squeak a lot whenever Blink goes to feed them and sound a little bit like baby birds. Blink seems to be keeping up with feeding a big litter well and is still slightly heavier then her pre-pregnancy weight.