Pros	Cons
Inbreeding Breeding very closely related rabbits such as sister to brother, father to daughter.	Like gene pairs Eliminates tissue rejection Eliminates heredity differences	Depression Decreased litter size Increased susceptibility to disease
Outcrossing Breeding unrelated rabbits into your line.	Maximum genetic diversity Vigorous offspring Large litters	Poor Lab use
Linebreeding Breeding rabbits with a common ancestor, such as a grandparent.	Similar gene pairs	Decreased level of negative traits as inbreeding
Crossbreeding Crossing different breeds together.	Produces new breed or variety Hybrid vigor	Unacceptable for show

Basic Information on Rabbit Breeding

What is linebreeding?

Linebreeding is a simple but controversial concept. Linebreeding is a program that produces animals from a single line of descent and from a common ancestor.

Linebreeding is built on the principle of "breeding like to like to get like." It affords the serious rabbit breeder the opportunity to set a type in the shortest amount of time. It also “narrows the gene pool.”

The greatest danger in a linebreeding program is that it intensifies all of the genes--good and bad. In other words, if you have a line of inherently quality show rabbits, breeding like to like—quality to quality--should result in a very consistent, and higher quality line of rabbits.

If, at the same time, this line of rabbits consistently lacks depth, then breeding like to like should result in an intensified line of poor-depth rabbits. In a linebreeding program, you, as the breeder, find out what is good and bad about your program in a hurry. The only way to offset the intensification of undesirable traits in a linebreeding program is to ruthlessly cull the undesirables from the herd

How is inbreeding different from?

Inbreeding is the mating of animals that are more closely related than the average degree of relationship within the population. Linebreeding is the strategic use of inbreeding to improve traits found in one family line. The math used in linebreeding is not very difficult, but it is quite interesting.  The inbreeding coefficient is a percentage of the probable chance that genes will double when related animals are mated.  It is often used in determining whether or not to mate two related animals because the higher the inbreeding coefficient is, the more likely it is that genes will double, whether they be good or bad.

Basically inbreeding is an intensified form of linebreeding, with the sole difference being in the genetic closeness of the rabbits being bred to each other.

Among the advantages of inbreeding, is that it affords the surest and quickest method of fixing and perpetuating a desirable characteristic or group of characteristics, it tends to create lines or strains of animals that are uniform in type, and it keeps the closest possible relationship to a desirable ancestor.

The disadvantages of inbreeding are that it almost certainly increases the proportion of undesirable breeding stock, with genetic abnormalities often appearing with increased frequency.

What is crossbreeding?

Crossbreeding (outcrossing or outbreeding) is the opposite of inbreeding, i.e.: increasing the number of heterozygous pairs. This is commonly known as “widening the gene pool.” Outbreeding is the mating of animals, which are less related than the average relationship of the population. Thus outbreeding is practiced most commonly between families.
Of the two breeding methods, outcrossing involves the least amount of risk. By mating rabbits that are unrelated, the chance of intensifying undesirable traits is minimized.

Unfortunately, due to the heterozygous, or dissimilar, genetic nature of a group of unrelated rabbits, the chance of intensifying desirable traits is likewise diminished.

Often times, the most consistent results in an outcrossing program are obtained when the outcross buck is, himself, a strongly linebred individual

Whether you decide to build your program on the principles of outcrossing or linebreeding, or a combination of the two, it is important to remember that, scientific discoveries notwithstanding, rabbit breeding remains much more of an acquired craft than an applied science.

There is no secret, and there is no magic formula. It's knowing your rabbits, studying them every day and being honest with yourself when it comes time to make your breeding decisions.