Line breeding

Brief theory guide on OB breeding – Line breeding

In principle, it can be distinguished between uncontrolled mating and line breeding. In genetic terminology, line breeding refers to mating within a specific breed in which a certain number of genetic lines is available. Assuming that the breeding success primarily translates in a standardization of the genetic base for a specific trait, all breeding successes can be ultimately attributed to line breeding, regardless of the breeding technique. Moreover, assuming that line breeding occurs only within a closed breed system, two types of line breeding exist. The first one combines the lines with one another, thus leading to a blood relation. The second system groups different non-related lines together, showing similarities with respect to the traits to be influenced and, most importantly, sharing the same breeding aim. In practice, these two systems are combined together - intentionally or unintentionally. The long term breeding strategy shall aim at establishing the qualitative and quantitative traits throughout all available lines.

Line breeding requires less “rules of the game” to be successful. This is particularly important if line breeding and, as a result, close breeding are implemented in a targeted way.

In principle, a distinction has to be made between close breeding and inbreeding. Consequently, breeding and mating are two different concepts. Breeding occurs based on the pedigree of paternal and maternal lines from the third generation. It thus focuses primarily on the 3rd to 6th generation of ancestors.

A second important rule is the systematic line change in the last mating, so that some fresh blood is always provided. A cow that, for example, descends from the U line shall therefore be mated with a sire from the G line.

A third rule is blood relation. The maternal line of the father should have lines that are present in the female animals too. Fourth, blood relation should be the optimum and not the maximum one. In other words, the optimum level of line compaction is 2x2 lines. In practice, this could mean that, in a mating, the U and the G line for example could be represented twice each, with the addition of lines showing similar qualities.

In a targeted mating, the sires that define a bloodline should not belong to the same generation up to the 4th generation of ancestors. This also applies, in principle, to the female animals that define a bloodline.

To conclude this introduction on line breeding, as it is applied and implemented on Original Braunvieh, a couple of words should be spent on breeding dynamics. It is mainly characterized by the different impact of strong and weak traits and is particularly important for traits with low heritability. If such a trait, e.g. persistency, as to be improved, there must be two strong lines against a weaker line. Please note that one single strong line can be “destroyed” by a weak one, thus leading to a significant variance for this trait in the offspring.