THE USE of cross-bred dairy animals has found favour with some progressive dairy farmers, but is the practice proving to be worthwhile? In this article, Andy Dodd, AHDB Dairy’s technical manager, and Sharon Lauder, AHDB Dairy’s extension officer, quantify what happens when you cross-breed.

WHILE IT can be beneficial, the exact effect of breeding for hybrid vigour (heterosis) is very difficult to measure in dairy cattle.

The term refers to the tendency of a cross-bred animal to have qualities that are superior to either parent as long as there is sufficient genetic difference between the breeds, as seen in Table 1.

The evolution of genomic testing, especially in heifers, will demonstrate more clearly exactly how helpful it is, with farmers being able to test heifers at birth to measure their genetic potential with 65%-70% accuracy.

Various cross-breeding trials around the world involving Swedish Red, Norwegian Reds, Brown Swiss, Jerseys, Montbeliardes and Holsteins have found the main benefits tend to be health traits.

Research in New Zealand, California and Ireland have seen increases in health traits of between 10% and 18%. Production benefits have also been found but these tend to be lower, around 6%.

To gain from hybrid vigour breed and bull selection is paramount. It is vital the breeds selected for cross-breeding meet each individual farm’s system, contract and management style.

Once the breeds are selected, it is recommended that farmers use the Profitable Lifetime index (£PLI) to select the bulls to be used in a breeding programme. There is often more variation between bulls within a breed than there is across breeds, so a poor decision when selecting bulls at this stage can have significant consequences in the long term.

It is vital when selecting bulls that strong traits in the dam are maintained to ensure genetic improvements made in previous generations are retained and emphasis is then placed on weaker traits.

The retained benefits of hybrid vigour in future generations vary depending on how many breeds are used.

A two-way cross will maintain approximately 67% of the benefits, a three-way cross 85% and four-way cross 94%. However, farmers need to decide what sort of cow will best fit their system and contract rather than cross-breeding purely for the benefits of hybrid vigour, which should just be seen as an added benefit.

Next year, will see the introduction of genomic testing for most major dairy breeds with ongoing work looking at developing genomic testing for cross-breds. Scottish farmers will be able to find out more at a series of AHDB Dairy meetings on breeding and genomics which will be held during 2017.