MouseFancier.com

Percentage vs. Perception

Written by A. Hamilton in October 2007

Owning English mice is all the rage these days. However, does breeding English stock into one’s lines make a difference? Or can the same results be achieved without shipping mice from overseas?
            First and foremost, not all English mice have the highly sought after “Show Type”. This is something that has to be achieved through selective breeding. Even some current varieties in the UK do not have nice type. Most of these are marked varieties.
            Many, many years of selectively breeding has proven that large perfect type and perfect markings almost can not be achieved. Since breeders in marked varieties cull to markings, this often means keeping the smaller, lesser typed animals.
            So if a breeder in the US were to import a variety, such as, Broken Marked to start a line of English typed stock, the type would not be there to begin with. They would be nice, but the animal would most likely not have perfect type.
            Just as there are good and bad breeders in the US, there are good and bad breeders in the UK. Not all UK breeders are able to spot a decent typed animal, and some are skating by on luck. If one decided to import, they would do best to purchase mice from an experienced breeder who has wins on his or her breeding stock. This insures that one is not merely receiving pet store quality UK mice.
            There are a few breeders in the US now that have achieved amazing results with their stock by crossing in English mice in the distant background. There are other breeders who have English mice or percentages of English, and since they only bred for certain features the type is no longer there.
            Even if one has stock directly from the UK or overseas, there is always room for improvement. The first key to achieving an ideal show animal is to know what you are looking for. Type is not just a big mouse with big ears. One has to look at the whole mouse, the whole package.
            Does a mouse being English or having a percentage of English parentage mean that it is better than another mouse without or with very little English in it? No. All mice have their own flaws. Instead of judging the quality of the mouse by the pedigree presented, the mouse itself should be examined.
            Below is a chart listing the percentage of English in the background vs. the type score for the individual mouse. Not all features were looked at, merely a selection of the more popular features:

Comparison Chart

	Head	Tail	Size	Ears
> ¾ English buck	F	G	G	G
¾ English buck	G	FP	G	FP
½ English doe	F	G	F	G
¼ English buck	G	G	F	G
> ¼ English doe	G	F	F	G

*Ratings given when compared to mice with no traceable English lineage.

So what does this chart show? The ideal is that a mouse where the parents have been carefully selected for that pairing can be just as good if not better than a mouse with a higher percentage of English. The ¾ English buck, while a good sized animal with a nice head, actually had very small ears and a very short tail. This buck was line bred from 100% English stock with BIS wins in the pedigree. This same buck had a littermate who had better ears, better tail, better head, but smaller size.
There is more to type than what was looked at in this example, but this gives an idea of what can be accomplished. The mouse that was less than ¼ English was selectively bred using two very nicely typed mice that had a traceable history of English lineage that was not present in a 4 generation pedigree.
So when choosing mice for breeding, the percentage of English in the pedigree does not necessarily guarantee that the mouse will be better typed. Remember, genetically the poorer type of the animal crossed to the English (assuming it is a show typed English to begin with) can be inherited just as easily as the nicer type.

Some photos of English and % English mice:

1/2 English doe