Weighing up the potential benefits of crossbreeding
Jersey crosses deliver real returns
Crossbreeding popularity was low until recently, fuelled mainly by international breeding goals focusing only on milk production, for which the Holstein excelled. However, as breeding goals broadened to include more functional traits, such as fertility, sires of other breeds started to compete with Holsteins. With the advantage of heterosis, crossbreeding became a very real alternative.
Heterosis is the additional performance observed in crossbred animals over and above that predicted by the EBI. It varies between breeds; the greater the difference between breeds the greater the expected heterosis. For example, the heterosis between a Holstein-Jersey-cross will be greater than the heterosis from a Holstein-Friesian cross. Also, heterosis tends to be greater in fertility and survival traits. A recent estimate of the value of heterosis between the first cross of a Holstein and Friesian is €50 per lactation compared to €100 per lactation between a first cross of a Holstein and Jersey. This benefit is halved in the next generation if the crossbred animal is mated back to either of the parental breeds. The economic benefit of heterosis was substantiated by recent economical analysis of a controlled Moorepark experiment.
Relative to a group of Holstein-Friesian cows from sires with an EBI €105 (milk sub-index of €58 and fertility sub-index of €36), crossbred Jersey cows from sires with an EBI of €132 (milk sub-index of €75 and fertility sub-index of €80), when modelled on 40ha, were more than €18,000 more profitable. This is more than €180 more profit per lactation with the Jersey crossbreds relative to the Holstein-Friesians on the study. The difference was due mainly to a combination of increased milk receipts, improved fertility and survival of the Jersey crossbred -- explained through greater sub-index values of the Jersey crossbreds -- but more so from heterosis in the crossbreed. Similar benefits have also been observed for Holstein-Norwegian Red crosses.
What is not yet clear is the long-term implications of different crossbreeding strategies and how these compare to long-term selection using the Holstein Friesian, and where a national breeding programme identifying elite Irish Holstein-Friesian is in place to ensure genetic gain in traits pertinent to Ireland is constantly being achieved. Nonetheless, if genetic gain in EBI in other breeds can compete with that achieved within the Irish Holstein-Friesian then there is no doubt that crossbreds will become a familiar sight in profitable Irish dairy herds.