8 July 2010

3 minute read

Europe

Although dairy farming has made excellent progress in recent years with the Holstein-Friesian cow, it is now generally accepted that breeding programmes with a primary focus on yield have inadvertently resulted in increased levels of infertility and reduced health and longevity. Crossbreeding has been suggested as one option by which some of these difficulties can be overcome.

Potential benefits of crossbreeding include the ability to introduce desirable traits from a ‘second breed’ into an existing population, and the positive impact arising from hybrid vigour. Hybrid vigour describes the additional performance benefits that can be obtained with a crossbred animal, over and above the mean of the two parent breeds.

For example, if Breed A has a lactation yield potential of 6000 litres, and breed B has a lactation yield potential of 8000 litres, the offspring of the two breeds might be expected to have a lactation yield potential of approximately 7000 litres. However, in the example given the actual production of the crossbred cow is 7350 litres, with the extra 350 litres of milk over and above that expected being due to hybrid vigour. Hybrid vigour is known to be particularly beneficial for traits such as health and fertility.

Research programme

Does crossbreeding have a role within the Northern Ireland dairy sector? This question is currently being addressed in a series of studies being undertaken by the Agri-Food and Biosciences Institute Hillsborough (AFBI), with the research funded jointly by AgriSearch and DARD. In one recently completed study, spring calving Jersey x Holstein crossbred cows were compared with pure Holstein cows over a three year period.

These cows were managed on three different milk production systems, with concentrate levels within these systems approximately 500, 1000 and 1600 kg per cow per year. This study was managed by Elaine Vance, a PhD student who is being funding through a DARD Postgraduate studentship.

Findings to date

Over the three years of the experiment, the Holstein cows produced approximately 600 litres more milk per lactation than the Jersey crossbred cows. However the crossbred cows produced milk with a significantly higher fat and protein content than the Holstein cows. When milk production was expressed in terms of milk solids yield (kg of fat plus protein) there was no difference between the breeds, with yields of 467 and 471 kg for the Holstein and crossbred cows, respectively. At a milk price of 25 pence per litre, the value of milk produced was £1617 and £1560 for the Holstein and crossbred cows respectively.

Although the crossbred cows tended to have a lower somatic cell count compared to the Holstein cows, this difference was not actually statistically significant. Nevertheless, 29% of Holstein cows had at least one incidence of mastitis per lactation, compared to 16 per cent of the crossbred cows.

Perhaps the most striking observation with the crossbred cows in this study was their significantly higher level of fertility. The crossbred cows exhibited signs of heat much earlier than the Holstein cows, had higher conception rates to both first and second service, while a greater proportion of cows were in calf after the first 12 weeks of the breeding season.
Conclusions

The findings of this study are extremely promising, with crossbred cows achieving similar levels of performance, and much improved fertility, compared to the Holstein cows. However, this study involved relatively low input grassland based systems. Would the performance of the crossbred cows be equally impressive within a higher concentrate input systems? This very issue is currently being examined at Hillsborough.

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