new publication from the University of Nebraska summarizes the effect of dairy cattle inbreeding on milk production.

The finding is consistent with previous studies: As inbreeding increases, milk production decreases.

Study results show that there are essentially no differences in production until about 6 percent inbreeding is reached. From this point forward, decreases are significant. At 6.25 percent inbreeding — which occurs, for example, from mating a sire with its great granddaughter — the researchers noted a decrease of 34 pounds. When inbreeding increased to 18.75 percent, inbreeding resulted in an 852-pound loss in production.

To avoid these inbreeding depressions, it is important to know the ancestry of both animals and the sire used, study authors caution.

This inbreeding study involved several hundred thousand lactation records used to estimate the amount of milk lost due to inbreeding.

Source: University of Nebraska