Effects of high inbreeding levels
When parents are closely related inbreeding occurs. Pure-inbreeding leads to inbreeding - and genomic selections will increase inbreeding even more rapidly. Inbreeding results in animals that have more health and reproduction problems - and therefore lifetime production will decrease. Inbreeding levels over 4% will give depression in the offspring. Holstein populations are closely related and show inbreeding levels between 5% and 8%. Holstein bulls that are used nowadays have over 10% inbreeding rates. The high genetic level of these bulls will not show in their daughters anymore. Due to inbreeding the results will be worse than expected. This generally leads to a decreased fitness of the population, known as inbreeding depression. Genetic defects such Blad, CVM etc, will occur. All AI-centers use genomic-DNA selection in their breeding programs. This is resulting in faster inbreeding. The promised genetic levels will not be expressed in the results at dairy farms. Lifetime productions will not go up. Cows can only perform if they are supported with costly management tools. Feed costs will go up. More young stock is needed.
Only crossbreeding can solve inbreeding. The very good and sometimes even surprisingly results of ProCROSS can be explained by the inbreeding problems in Holstein and the heterosis using ProCROSS.
Inbreeding leads to the following most mentioned situations:
Table 2. Average inbreeding of Holstein females in the USA.
In other countries around the world we see the same increase in inbreeding coefficients.
Table 3. Inbreeding coefficient of well known bulls in the Netherlands:
Table 4. Inbreeding coefficient of well known bulls in the USA.
Table 5. Inbreeding coefficients of bulls in Canada.
Their influence will only get bigger because of the influence that their sons and daughters will get. For example; Planet is used as a “outcross” bull in the Holstein breed because of his different pedigree (Taboo x Amel x Duster). At this moment Planet already has inbreeding levels of 6.5% (USA) and 7.3% (Canada).
Table 6. Genetics inbreeding examples
|Parent - child||0.5|
|Grandparent - child||0.25|
|Great-grandparent - child||0.125|
|Full sister - full brother||0.5|
|Half sister - half broter||0.25|
|Nephew - niece||0.125|