Many articles and various approaches have been written over the past couple of years on how to deal with inbreeding in dairy cattle (Read more: 20 Things Every Dairy Breeder Should Know About Inbreeding and INBREEDING: Does Genomics Affect the Balancing Act?). However the herd breeding approach towards inbreeding that is best suited for individual dairymen is not a one size fits all.

Out-Crossing

Frequently the method recommended is to find out-cross sires and to use them on a herd rather than closely related or inbred sires. The Bullvine produced such a list a few months back (Read more: 12 Sires to Use in Order to Reduce Inbreeding). However totally out-cross sires are almost non-existent as very few Holstein A.I. breeding bulls do not contain, in their first three generations, a cross to, at least, one of Bolton, Blitz, Durham, Goldwyn, Oman, Planet, or Shottle.

Sires From the Past

But we should not despair. This problem has been the same challenge for the past century. In the past there were concerns about too much concentration of the Holstein bloodlines when Rudolph, Blackstar, Valiant, Elevation, Astronaut, Rockman, the Burkes and the Montvics were in their hay days. It is not new in 2013. A few years back Holstein International produced an article on the extreme focus, around the world, on Blackstar as he had a few hundred sons that were sampled in A.I. But we moved on past the Blackstar focus and outcross sires came along and saved the breed from a one sire focus.

Recent Out-Crosses

The most recent ‘heroes’ to assist with avoiding inbreeding Holsteins have been Shottle, Oman and Planet. They themselves have average to below average inbreeding percentages – 6.25%, 5.06% & 7.27% respectively. We must remember that it was not their lower inbreeding percentages that attracted breeders to them it was what their daughters could do in every breeder’s herd. They were all out-crosses when they arrived on the scene. However, they were all used heavily, perhaps too heavily. In fact it is not the bulls that are the problem. It is our over abundant use of sires on close relatives that lead to them becoming inbreeding concerns.

Why Inbreeding was Practiced in the Past

Before the era of genetic evaluations, inbreeding was employed in what was called ‘Line Breeding’. The concept was to find a family that had the attributes a breeder wanted and then to double, triple or even quadruple up the cow or bull in the pedigree of the next generations. Breeders persist in using the line breeding approach even though we now have very accurate genetic indexes. As a result we are creating an inbreeding problem for ourselves. Especially for traits like fertility, immunity, vigour and longevity. In 2013 these traits are coming to the forefront in the breeding of dairy cattle.

What is Average for Inbreeding?

In the USA inbreeding is expressed by a term called Inbreeding Coefficient, whereas in Canada it is called Inbreeding Percent. The average value for each appear to be similar with the average inbreeding in Holsteins in Canada being 5.87% in 2009.

Here are some examples of inbreeding percent that can be expected from within family matings:

• Brother- Sister     25%
• Half Brother – Half Sister   12.5%
• First Cousins    6.25%
• Second Cousins    3.13%

In other words, the average animal in the Canadian Holstein populations was almost equivalent to being the result of mating first cousins.

Sire Selection & Inbreeding

Choosing sires to minimize inbreeding is not as simple as going to CDN.ca or DairyBulls.com and finding the top (lowest) bull for inbreeding percentage or inbreeding coefficient. Thus eliminating from your breeding program any bull that is over average for inbreeding. You must also consider the bloodlines in your herd and the inbreeding of your females.

It can happen that a cow and a bull each have low inbreeding percents but due to being from similar bloodlines the resulting progeny are inbred. Take Goldwyn for example. His sire, James, has an inbreeding percent of 3.67%. His dam, Baler Twine’s value is 9.74%. Yet when mated because of the intense line breeding to both Grand and Aerostar, Goldwyn’s inbreeding value is 15.69%. The line breeding did allow for his genetic make-up to be homozygous at many loci. We all know how he stamps out show type. However breeders planning to line breed further with Goldwyn in the pedigree should be concerned about the definite possibility of inbreeding depression for health and fertility traits. Sire stack does not show inbreeding as accurately as inbreeding coefficient or percent does.

For breeders interested in some bulls with below average inbreeding values, The Bullvine offers the following lists. Note that we have chosen bulls with high total merit indexes and above average for Daughter Pregnancy Rate and Daughter Fertility. There is no benefit to using a sire that has a low inbreeding number yet produces daughters that have low fertility or are lacking in any of healthy fast growing calves, immune animals, SCS, Feet & Legs or Mammary System. Of course the lack of heifer information across herds could be our Achilles Heel in the not too distant future in genetically advancing our heifers.

Tables 1 – Top Sires with Lower Inbreeding Levels

The Bullvine cautions breeders using genomic sires to not use just one sire. Many of the top sires on the genomic listings have average to above average inbreeding numbers. So it is best to use many genomic sires. Many breeders wisely use from 5 to 20 doses of a genomic sire and then move to another high genomic sire.

Six Suggested Practices

1. Avoid using any sire that has above average inbreeding numbers especially if his pedigree has similar sires to the females in your herd.
2. After identifying sires with average to below average inbreeding numbers, make sure they are superior for traits important in your breeding program like fat yield, protein yield, feet & legs, mammary system, udder health and fertility.
3. Use a sire’s genetic and inbreeding indexes when selecting sires and do not practise line breeding.
4. If there is a sire that you would like to use but his inbreeding index is on the higher side then use his top two non-inbred genomics sons.
5. Use computerized sire mating programs as they consider inbreeding when making sire recommendations.
6. A.I. organizations should publish the inbreeding values for the sires they sample, prove and market.

The Bullvine Bottom Line

Inbreeding is a consideration but not the driving force when it comes to improving the genetic merit of a dairy herd. Line breeding served its purpose in the past but now can be detrimental to lowering inbreeding in dairy cattle. By following the suggested practices you will not only be able to better understand inbreeding, you will actually accelerate you genetic advancement, by not avoiding those sires that you thought would have been a inbreeding problem.  It’s important to remember just how much effect inbreeding will have, and how does that compare to the difference in genetic merit between the sires you are choosing from.

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