Reduced biological fitness can lead to loss in profitability

Keeping an eye on inbreeding in your herd is crucial to secure the profitability of your dairy farm. Reduced biological fitness can manifest itself in two ways: genetic defects for monogenic traits and inbreeding depression for production and health traits. Both can lead to loss of profitability in your herd.

Inbreeding can be viewed on two different levels. At the farm level, it is important to monitor inbreeding to avoid a reduction of biological fitness due to monogenetic disorders/diseases and inbreeding depression. Here you can use the inbreeding coefficient of planned matings to keep inbreeding under control on the farm level.

At a population level, high inbreeding trends are related to loss of genetic diversity, which, among other things, influences the prospect of achieving genetics gains from a longer-term perspective. Here, the rate of inbreeding (average level of inbreeding in one time period compared to another time period) is more important to monitor than the inbreeding level itself.

Control inbreeding with VikingHolstein

VikingGenetics is running a responsible breeding scheme for VikingHolstein with a focus on future inbreeding when selecting young AI bulls.

You can control the inbreeding level at your farm by:

using VikingHolstein genetics
making mating plans which allow you to set a limit on inbreeding

Both elements are important to avoid inbreeding at the population level in the short-term. However, in the longer-term inbreeding needs primarily to be handled by the AI companies that are responsible for the breeding program.

How does inbreeding develop in the era of genomic selection?

In 2020 the World Holstein Frisian Federation (WHFF) collected information about the development of inbreeding coefficients for cows and heifers from 26 countries worldwide, including Denmark, Sweden, and Finland. The information is collected in a presentation, which should had been given at the planned WHFF World congress in August 2020, but has been made available on the WHFF website instead.

The increases in inbreeding level (% units) per year are shown for different birth year periods of females for some of the largest Holstein populations in the world and the three Nordic Holstein populations.

The FAO recommends that increases in inbreeding level should be less than 1% per generation. That means that if the generation interval for dairy cattle today is four years, then annual increases in inbreeding should be below 0.25% units per year to meet that recommendation. The table shows that some countries are close to, or slightly above, that threshold over the last ten years.

The average increase in inbreeding level (% units) per year and country in different time periods (Source World Inbreeding Trend in Holsteins - Presentation by Egbert Feddersen- view here http://www.whff.info/)

Birth year of females	1990-2000	2000-2010	2010-2020
Italy	0.18	0.14	0.26
US	0.19	0.11	0.26
Canada	0.26	0.08	0.25
Finland	0.09	0.19	0.20
Netherlands	0.17	0.03	0.16
France	0.20	0.10	0.16
Germany	0.16	0.08	0.15
Sweden	0.19	0.13	0.12
Denmark	0.18	0.12	0.10

Large differences in increases in inbreeding coefficients across the Holstein populations

The results show large differences in increases in inbreeding coefficients over the last ten years where the genomic selection was the key tool for selecting breeding animals.

Countries like Italy, the US and Canada have experienced an increase in the inbreeding level, which is twice as high (0.25-0.26% units per year in the last decade) as the one observed for Sweden and Denmark (0.10-0.12% units per year) in the same period.

In Finland, we observe a different development in inbreeding level when compared to Sweden and Denmark. The introduction of Holstein Frisian was much later in the Finnish population than in Sweden and Denmark. This led to a lower level of inbreeding in 1990-2000 and a higher in 2000-2020 in Finland than in Sweden and Denmark; even though the same pool of AI bulls has been used since VG was formed in 2008.

The results show that inbreeding in most cow populations has increased when the genomic selection was introduced (2010-2020) compared to the situation when the traditional progeny test scheme was the key element in the breeding program (2000-2010).

For the three Nordic countries, the increase in inbreeding in the Holstein population was kept at the same level in the period from 2000-2020.

Dealing with inbreeding in the genomic era

The results in this analysis indicate that AI companies in different countries deal differently with inbreeding in the breeding programs. Inbreeding has increased significantly after the introduction of genomic selection in many of the countries.

However, the results from the Nordic countries prove that by considering future inbreeding in the breeding program, it is possible to avoid an increased rate of inbreeding. Controlling inbreeding in the breeding program requires that AI companies select a larger number of sires and make a tradeoff between the bull’s genetic merit and its effect on future inbreeding.

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What are inbreeding and inbreeding depression?

Inbreeding is the mating of individuals that are related by ancestry and results in a reduction of heterozygosity and an increase in homozygosity. It can lead to reduced biological fitness.

Inbreeding depression is the effect of inbreeding measured as the reduction in phenotypic performance with increased levels of inbreeding within a population, for example, reduced milk yield or fertility caused by inbreeding.

Article based on “Inbreeding trends within the Holstein population worldwide” by Gert Pedersen Aamand, Jukka Pösö, Ulrik Sander Nielsen, and Freddy Fikse, 2020-11-02-Inbreeding-trend-within-the-Holstein-population-worldwide_final.pdf (nordicebv.info)