Line breeding breeds success, but at what cost?

What do we mean by Line Breeding?

Line breeding is a mild form of in-breeding, but its important to note that we're trying to fix good attributes by crossing related birds, rather than trying to produce un-natural, weak or sickly birds.

In-breeding occurs in nature, you only have to look at Cheaters, who can be genetically traced back through time to a single female.  Another example would be the Lizard canary, which survived due to a single breeding pair just after the second world war.  Obviously a small gene pool, bring with it risks, so we need to be careful when selecting our pairs to ensure we gain the benefits of line breeding without impacting the health of our birds.

In-breeding poor quality birds won't produce good quality birds.  We need to identify good qualities in two birds & line breed to fix that quality e.g. the size or shape of a bird.

The Benefits of Line Breeding

If done well, over time the quality of your stock will improve & you will achieve consistency of appearance through-out your stock.  If your stock have improved to the stage where they regularly win at shows, then you can look forward to regular success year after year.

A Word of Caution

Line breeding can highlight genetic defects, don't continue to breed from these birds in the hope the defect will disappear, because it won't.  The reason these defects will stick is the same reason the qualities will stick & that is that the genetic make-up of your birds will become similar.  The term used for birds with similar genetic information is Homozygous.

As well as physical traits like shape & size you may also notice birds who twist or cock their heads strangely.  Other may be prone to fits if you move them from one cage to another or may even be blind.  The general rule is that any health issue shouldn't be automatically attributed to line breeding, but these traits should be logged & future young should be examined with a keen eye to ensure the trait isn't inherited.

Selecting Pairs for Line Breeding

• Obviously select the best quality birds as if you were type breeding e.g. shape & size.  Where possible double up on good qualities & never double up on bad qualities e.g. both have poorly defined head shape, which will fix poor quality head shape in the young.

• To achieve a homozygous bloodline don't rush in & use sibling pairs.  Most top breeders use half bothers & sisters from the same father, but similar pairings could be achieved via the same mother or in a more extreme case by pairing the father to daughter or mother to son, although this is referred to as "In Breeding" as opposed to "Line Breeding".

• If you have an exceptional adult that you retain year on year you can repeatedly line breed using this bird initially to daughter/son, then granddaughter/grandson etc.  This will produce homozygous young.

• If you need to introduce an out-cross to enhance the shape, size or colour, buy the best you can & pair them to two homozygous birds of your own.  If the young aren't of a high standard the gene mix may not be working, so try another outcross from a different source.  By breeding to two of your own homozygous young you ensure you have half brothers & sisters for the following years breeding season.

• Introducing an out-cross every 5th year will help keep a healthy gene pool, but isn't necessary if your stock are healthy & don't display negative traits.

This page was last updated on 18-Nov-2005 .