Line Breeding … OK or not?

I have a question regarding linebreeding. Is breeding dam to son considered linebreeding? I have read many articles and they all say a different thing. Some say yes it is ok and some say no. What are your views? If this is not ok what is ok in linebreeding?I have a question regarding linebreeding. Is breeding dam to son considered linebreeding? I have read many articles and they all say a different thing. Some say yes it is ok and some say no. What are your views? If this is not ok what is ok in linebreeding?

Story originally posted by: Michael Lowder, DVM, MSUniv. of GA School of Veterinary Medicine

Hi,
I have a question regarding linebreeding. Is breeding dam to son considered linebreeding? I have read many articles and they all say a different thing. Some say yes it is ok and some say no. What are your views? If this is not ok what is ok in linebreeding?

Cammy,

Inbreeding can be defined when you are breeding horses that are relatedâ within the first 4 to 6 generations and, therefore, with probably more than the average number of genes in common. Inbreeding is commonly divided into two categories, viz., closebreeding and linebreeding.

Closebreeding is the mating of a full brother to sister, of sire to is daughter, or dam to her son. These types of matings give the greatest concentration of similar "blood," and this concentration appears close up in the pedigree. In fact, the concentration is discovered in the second generation back in all the cases listed as examples of closebreeding.

Linebreeding is the mating of horses of wider degrees of relationship than those just stipulated for closebreeding, and is generally directed toward keeping the relationship high to some desirable ancestor or Îlineâ of ancestors. These would include half brother and sister or matings of horses more distantly related; e.g., cousin matings, etc. Thus, two horses that have any close-up ancestors in common are related, and, if you mate such horses, you are practicing some degree of inbreeding.

A few things to think about, an inbred horses is likely to be homozygous in more sets of genes than is an outbred animal. Inbreeding creates no new genes but allows those already present to get into homozygous combinations.

Inbreeding results in improvement or deterioration depending entirely on the genes present in the related horses. Only those breeders whose herds are large and have more than average merit should practice closebreeding. Linebreeding should have a greater vogue than it has had in the past.

Inbreeding will be successful (1) if the good genes pretty well out-number the bad ones to start with, (2) if the breeder has more than average skill in planning his matings, (3) if the breeder can and will practice very rigid selection (cull a lot of horses). Finally, it isn’t the system of mating it’s the genes in the horses and the intelligence in the breeder that make the breeding.

Thanks, Dr. Lowder