Evaluate Sires on Home Country Type Proofs

Is it any wonder that more and more people are questioning the value of Interbull type proofs? For years there has been a quiet understanding that a 'home field' advantage exists that helps protect domestic proven sires against foreign products. The reasoning was 'better to err on the side of caution than to overestimate'. Still, more recently as the globalization of genetics has taken root, Interbull assessments for low heritability traits has become more than just a little bit bothersome. As many AI organizations begin marketing products from a variety of proving environments, the realization is quickly made that selling European proven products using Interbull type proofs is all but impossible. They simply do not do justice to most bulls.

To demonstrate how Interbull type assessments are flawed lets use Alta's well proven sire Timlynn Adam as an example. Rated at +1.79 PTAT in November 2002, Adam's Dutch evaluation for type is currently listed at a respectable 109. In a perfect world, this would suggest that Dutch bulls rated 109 for Final Score should generate a US expresion near +1.80 PTAT, just like Adam. After all, conversion formulas should work both ways. Alta has three Dutch proven sires, that have the precise rating of 109 for type in the Netherlands. Still, their US conversion is not even close to +1.80 for PTAT!

The above example demonstrates that something is definitely lost in the translation. Clearly, the conversion from the US to the Netherlands works better for Adam than for Dutch sires being expressed on a US base. Imagine in the case of Cassa having a Dutch proof in excess of 2 standard deviations above the breed average, only to have a US expression that brings him back to breed average.

The chart below provides a little more detail on how the expectation for US sires expressed on a Dutch base is quite different than Dutch sires being expressed in the US. Six sires from each proving environment when graphed show two entirely different equations - in a perfect world there should be just one line that works in both directions. The net result is that those faced with the prospect of providing potential North American customers with top rated Dutch bulls will have a difficult time convincing them that these in fact are top rated bulls based on their US equivalent type values.

While Interbull production numbers may provide a reasonable assessment of global products, allowing all sires to be compared directly against one another, when it comes to type proofs the same is certainly not true. That's why Alta has decided to market European sires using their 'home country' type information. Along with that decision comes a responsibility to educate producers on the proof terminolgy and ranges from the specific countries where those sires were proven. Simple diagrams like the one below help demystify what is commonly believed to be a complex subject. Additionally, it opens a window to a world of new genetic options that offer diversity and excellence in areas that may not be North American strengths.

In the US type proof information is expressed in standard terms where 0 is average and -3 and +3 represent the extremes. The curve shows that there are a vast majority of individuals evaluated close to the middle with very few at each extreme. Each country uses the same priciples to generate sire proof expressions although each applies their own scale to express those proofs. For example in Canada instead of a 0,1,2,3 scale as is used in the US, dairy producers have become accustomed to a scale 0,5,10,15. Still, there is a common rule of thumb that producers use where a +10 bull is believed to be comparable to one rated +2.00 in the US. By learning each country's proof range, one can quickly assess how an individual bull compares against other bulls within the population he has been proven in. While type may not be evaluated in precisely the same way in each country, this rule of thumb approach is increasingly becoming regarded as the best way to assess the merits of products proven around the world.

It is important to note that in many European countries even auxiliary traits are evaluated on the same scale as type traits. This is particularly useful in that only one scale needs to be learned. On the other hand it is important to note that for traits like Calving Ease and Somatic Cell Score, higher proof values are desired, which is opposite to the North American approach.

Will Interbull proofs for foreign bulls ever gain enough accuracy to be meaningful? Many noted breeding specialists around the world now believe it will never happen. Increasingly, dairy producers are becoming focused on traits with lower heritabilities - traits like Somatic Cell Score, Longevity, Milking Speed and other health traits. These traits will be very difficult to compare across borders. And as more and more of these traits become incorporated in National indexes like TPI, LPI etc, the more difficult it will become for foreign sires to compare well against domestic products. Call it a protectionist measure if you will. As a result, more and more producers are taking the time to learn the basics on various proof languages and discarding the Interbull notion.

Posted Jan 17th

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