A Fine Line in Genetics
When you are in the livestock business, you most likely want your individual animals to offer the best traits and qualities possible to set your operation apart.
Some producers opt to keep closely related family groups as a part of their operation, but there can be a fine line when it comes to breeding for quality or creating problems that can last for generations.
According to the University of Missouri Extension, the classification of linebreeding or inbreeding depends on the closeness of the biological relationship between mates, and a very fine line separates the two categories.
These practices can help you breed for the best – once you understand the differences – and select which one will help you accomplish your herd goals.
Inbred is a term that most people are familiar with, but just what exactly is inbreeding? Inbreeding is the mating of individuals that are related, such as parent and offspring, full or half siblings. In the broad sense, according to the University of Oklahoma, all members of a breed are related. As a result, any seedstock producer is practicing some inbreeding. Therefore, we generally reserve the term inbreeding for the mating of animals that are more closely related than the average of the breed.
Animals that have been inbred can sometimes have higher genetic performance, but should always be closely monitored for any poor qualities that need to be weeded out.
Inbreeding can have dramatic effects on a herd. OSU cautions that these effects are the result of individuals receiving identical genes from each parent. If the parents are related, it is more likely that they have genes that are identical. An individual receiving identical genes from each parent is said to be homozygous for that pair of genes. This would be desirable if the gene the individual received from each parent leads to superior performance. However, most animals carry undesirable genes that usually remain hidden unless the animal is homozygous. An inbred individual is more likely to be homozygous for any gene, so the animal is more likely to express undesirable genes, and hence, undesirable traits.
Linebreeding is actually a type of inbreeding, but the results are different. “Linebreeding is an attempt to maintain a high relationship to some outstanding ancestor while keeping inbreeding as low as possible,” Morgan Hartman of OSU stated in his article Breeding Matter III – Inbreeding vs. Linebreeding. “Linebreeding has been attempted in most breeds of cattle. It has the advantage of maintaining genes from outstanding individuals that are no longer available for breeding purposes. In linebreeding, the idea is to always keep the amount that any one animal contributes to the DNA of any descendent at or below 50 percent. With inbreeding you regularly will find a higher degree of influence. For instance, a sire/daughter mating will result in an offspring which carries 75 percent of it’s DNA from the sire and only 25 percent from the maternal dam.”
According to OSU, linebreeding should be attempted only in superior herds that have difficulty finding outside bulls that are of sufficient merit to improve that herd. The ancestor that is the object of the linebreeding should be clearly outstanding based on performance criteria and mating of close relatives should be avoided.