Cross-breeding with Holsteins

The benefits of cross-breeding can be obtained through European Holsteins

What to make of the big hoopla about cross-breeding in the US? It seems that there is more speculation than facts. The concept of crossing the US Holstein with various European or Scandinavian dual purpose breeds has gained a significant following over the past few years, but producers are right to be cautious. Although impressive first generation results have been reported, they are based on very limited data with no current data available to indicate what can be expected there-after.

Crossing two distinct breeds of cattle is done to exploit non-additive genetic variance – also referred to as heterosis or hybrid vigor. It’s kind of like adding two plus two and getting five. Generally traits which have low heritability (fertility, disease resistance, viability, mastitis resistance) benefit the most from heterosis (Sevill Wright, 1935). Higher heritability traits like production yield will not benefit much from the heterosis phenomenon and that is why there is much skepticism on the cross-breeding practice. After all, there is no breed that can come even close to matching the Holstein for production yield. One can instead expect to realize progeny that are basically an average of the genetic level of the two parents. In practical terms if Holsteins are crossed with lower-producing breeds, the progeny will have lower production compensated in part by higher percentages of fat and protein. Still the production yield would never come close to the Holstein.

Additional concerns expressed focus on results with the second filial generation (F2) in a cross-breeding scheme. Many people have expressed opinions but no one has facts to back them up. Theory says that any advantages gained in the first generation will be maintained only if hybrid vigor is maintained, which can only be achieved if a third breed is introduced. The resulting animal may look different, sometimes aesthetically awkward, but the hybrid vigor will be maintained. If one chooses instead to work with only one additional breed, in essence criss-crossing back and forth, the F2 will have significantly less hybrid vigor than the F1 and one might expect to make similar progress in two generations by simply selecting within a breed.

Many people forget that there are Holsteins in Europe and that they also provide the opportunity for gaining some hybrid vigor. While European Holsteins are related to US Holsteins, they provide an excellent opportunity to reduce inbreeding levels and in some cases even benefit from heterosis – and it can be accomplished without giving up significant production!

The US dairy industry should be cautious in its promotion of cross-breeding. Its easy to get caught up in the hype, but results to date should be viewed with a healthy measure of skepticism. After all, cross-breeding is not new. Results in the past have always been disappointing. On the other hand, have we perhaps missed the most obvious source for new genes? European Holsteins are an ideal way to incorporate new bloodlines, with it decreasing the negative impact that inbreeding has exerted on fertility and fitness.

Article by: Dr. A.P. Phatak
AltaPreg Field Fertility Specialist

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Posted Jan 10th

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