by Brenda Nelson

Created on: January 29, 2011   Last Updated: February 04, 2011

Linebreeding, and inbreeding, are similar and easily confused by a novice. Some knowledge of reading a pedigree is required in order to understand the difference of these breeding systems. Of note, these breeding practices are not exclusive to the livestock industry, breeders of other animals, such as cats, dogs, and horses, often follow patterns of linebreeding, and less commonly, inbreeding.

Understanding a Pedigree

A pedigree is a chart listing the parents, grandparents, and so forth, of an animal. The animal's name, or number, is listed on one side, often the left; to the right and above is the sire's (father's) name, to the right and below is the dam's (mother's) name. This continues back for as many generations as the pedigree is long.

Linebreeding

Linebreeding is when an ancestor is specifically singled out and breeding occurs to include that animal in the pedigree as many times as possible. As such a specific animal may be the grandsire on the sire's side, as well as the dam's side. More often linebreeding reaches the stage where the specific animal appears in the pedigree several times over.

Linebreeding often occurs when an animal is no longer living but breeders still want that animal's genes. This is is very common in the horse racing industry among breeders of Thoroughbred horses.

Inbreeding

Inbreeding is sometimes seen in a linebreeding program although in and of itself is often frowned upon in favor of linebreeding. Inbreeding is breeding within an immediate relationship, brother and sister, parent and offspring. Inbreeding tends to result in the occurrence of recessive genes showing up in offspring, and the concern is in regards to some of these genes being undesirable.

To Compare

Essentially linebreeding is slightly less intense than inbreeding. In rare breed animals, linebreeding often happens simply as a result of a small gene pool. In these rare animals it is very important that inbreeding be discouraged simply because it contributes to an already shrunken gene pool, and instead it is vital to select animals that are not closely related (called outbreeding).

When a breeder thinks of the purpose of his, or her, breeding program they must look at what they are breeding for. If the animal is to be slaughtered, a quick growth rate might be far more important than maintaining a healthy gene pool, as such inbreeding might be okay. If a producer is breeding with the intention of keeping an animal for show and/or breeding, then they need to focus on genetic superiority, as such inbreeding would not be desired, but linebreeding, or outbreeding, should be the focus.

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