an overview of my current breeding strategy and objectives

Background
I established the Zephyr line of rats over the course of a number of years, starting in 2004 with rats from several other lines, and I then incorporated additional outcrosses in 2009. After initially planning to breed for powder blue, I became very attached to american mink and cinnamon after it popped up in my early litters, and since then I have focused on conserving and developing varieties which are based on this gene, while maintaining the now distinctive 'Zephyr temperament' - confident friendly affectionate people centred rats with an intelligent curiosity and playful cheeky streak. Since the outcrosses in 2009, I have seen a general improvement in the common health issues of benign mammary tumours in the girls and hind limb degeneration in the boys, which both tended to occur at around 2 years, and lifespan has increased slightly, now often being closer to 2 1/2 than to 2. This improvement is possibly also reflected in a slower rate of development as kittens, so eyes open a few days later, and the moult happens a couple of weeks later, therefore I now home close to 8 weeks old rather than my original 6. These improvements are most likely also helped by an improved diet and more challenging housing resulting in leaner fitter rats.

Strategy
In the past I generally mated does at around 6 months, but there is a possibility that late fertility is connected with longer lifespan, so selecting the offspring of does that can be relied upon to breed older is one way to try to extend expected lifespan. It also enables breeding decisions to be made at an older age so that more health information is available. I began working towards breeding at an older age by testing (when appropriate) whether the does could manage a second litter at 9 - 12 months. Health is generally good in my lines, but I keep a constant eye out for any trends that indicate cause for concern, and rely on owners of Zephyrs to keep me up to date regarding their rats. Occasionally a particular litter will do badly when compared with other litters, and in these cases I don't breed on from them.

Breeding at around 8 - 10 months for a first litter has generally been successful so I am beginning to switch to an 8 month generation gap in most cases. There may be additional litters where necessary for test matings or if it is going to be advantageous for a doe to have a second litter, and there are always times when plans don't necessarily work out and a doe may be mated earlier or later.

I shall be 'tidying' up my lines as much as possible, separating them in terms of the genes they are expressing so that each litter has more of the varieties that I am needing for that line, and this should give me greater choice of which kittens to keep. My standard plan is to breed two or three litters in each generation for each line, with generations spaced every 8 - 12 months, plus additional test or development litters when needed.

Lines
I maintain a core line of rats expressing or carrying the american mink gene. These rats can be crossed into any of my side lines.

I formed my first side line when platinum (red eyed, pale icy coloured coat) and quicksilver (a ruby eyed variety with a bluer coat) reappeared in a litter in 2010, and my long term goal is to unravel the genetic differences between the two varieties. The platinum variety is not yet fully understood, and although my platinums definitely require american mink and pale british blue (caused by the same gene as the show standard british blue but probably with modifiers), quicksilvers do too, so it seems that platinum is constructed from particular versions of these genes and/or one or more modifiers. I shall keep some blue based carriers in this line to protect fertility, so will also have pale british blue and british blue agouti.

My second side line for havana and havana agouti emerged when an 'orange' gene turned up unexpectedly in Spring 2013, later confirmed to be red eye dilute, aka RED (denoted 'r' and responsible for buff and topaz). The show standard for havana was written many years ago and it's not known what the genetics of the rat it was based on were, however my chocolate american minks who are carrying 'r' match the standard well. Havana agouti is also a very attractive variety and I hope that both these varieties will become more widely bred.

In order to protect my progress with these lines, in the future I will aim to keep two strands within each line as separate from each other as possible. This means that if a problem crops up in one strand I can either drop that strand completely if it is serious enough, or use the stronger strand to bolster the weaker one.

I have a third side line for silvermanes begun in 2016 following an import from Canada, and as this is still a new line I will be exploring various options over the first few generations before settling on which varieties seem to work best with it. At the moment I am liking agouti, chocolate, and chocolate american cinnamon. This line also includes a dominant chocolate gene which may be interesting for other varieties. Details of this project will be documented on this page.

Current objectives
With regards to my main american line, I had been working to consolidate good dumbo, but I'm not happy with their ears, so while I may get dumbos pop up occasionally, I am no longer going to be planning my litters around them, which will mean fewer american line litters and the chance to expand other lines instead. In future I will focus on maintaining a basic line of black, agouti, american mink and american cinnamon, and will test mate when convenient to remove chocolate and buff from them so that they can be used to cross into the platinum line when required. I'm planning to introduce essex markings into an american cinnamon strand in early 2019. I will continue to work on improving type while also maintaining temperament.

My carefully laid plans for the platinum line have run into various problems, and sometimes it feels like I'm barely holding onto them! I will be using rats from my other lines to broaden the gene pool, as well as using an unrelated outcross for a second strand - these are likely to bring in some unwanted colour genes, so there may be additional test litters to screen for them. I finally have the platinum agoutis that eluded me for so many years, and would like to establish a strand for platinum agouti and british blue agouti which will also make quicksilver agouti, while the other strand will be mostly self platinum and quicksilver. My original investigations into platinum genetics remain on hold for the forseeable future.

I am aiming to make my havana line completely chocolate based, and will plan for some chocolates as well as chocolate americans and havanas. Most litters will be self based so that I can increase my selection options for havana, but I will keep havana agouti going as a secondary variety in one of the strands. Nimbus Rats will also be working with havana and havana agouti, using Zephyrs as foundations, so we will be able to share rats if necessary.

Within the silvermane line, I shall be selecting for stronger examples of the silvermane effect over the next few generations having focussed first on their temperament which now seems suitable for pet homes. My preferred base colours will be agouti (for the mask), chocolate (for the warm effect), and chocolate american cinnamon (for the glowing golden coat). Rats from this line will be kept out of my other lines, since it's not yet clear what else the outcross has brought in. I will also be assessing dominant chocolate americans as an alternative genetic version of havana.

2017 was a difficult year due to a couple of bouts of suspected parvo virus here. This virus is symptomless in rats except during pregnancy when it can affect the development of the foetuses, meaning that it's hard to track, and it's only when a litter fails that contingency measures can be put into place. As a general rule, by 3 months after initial exposure, all adult rats in the household will have become immune (thus taking a 3 month break from breeding and showing is recommended), but if new rats come in, or there are kittens, the period can be longer. Breeders find that cases of parvo pretty much disappear after a while, so epigenetics may play a part in rats eventually gaining protection, and it's deemed better to plough on than to risk losing lines. A blood test taken in early 2018 was negative for the expected parvo virus strains, so it's still not clear what was causing some litters to fail.