The Pros and Cons of Crossbreeding
Published 1 July 09
The pros and cons of crossbreeding -
For some dairy farmers who are looking for a cow which is easier to manage, crossbreeding may be able to offer the solution. But careful consideration needs to be given to the pros and cons, before embarking on this major change of direction.
Dairy farmers are too often turning to crossbreeding to supply a quick fix for problems in their herds, according to geneticist, Marco Winters, director of DairyCo breeding+. Although the crossbred cow can potentially bring worthwhile benefits in areas such as health, fertility and ease of management over the Holstein breed, other considerations - such as loss of milk production - need to be carefully weighed against the possible gains.
"First and foremost, farmers whose herds have underlying management problems will not cure those problems by introducing another breed," says Mr Winters. "Breeding is only part of a whole-farm approach and issues such as high cell counts, fertility and lameness must first be tackled through management.
"Sometimes genetics are blamed for underlying management problems, and if these remain present, crossbreeding is unlikely to be the solution."
But whatever approach to breeding is taken, the first step is to identify the herd's goals. "For instance, do you want to breed for lower cell counts, better fertility, or longer lifespans," asks Mr Winters. "And I'd suggest that once these questions are answered, the first place to look is within your own breed."
Although the Holstein's production has increased in the UK over the past 20 years, the recent emphasis in breeding has moved towards health and fitness traits, and genetic indexes for these traits are available. It is easy to identify the bulls which are predicted to transmit the greatest improvements in these areas and many in the Holstein breed offer plenty of scope.
"Search for the highest Fertility Index bulls; the lowest cell count bulls and those which transmit the best longevity, and use these, as required, to breed your herd replacements."
But recognising that some breeders are seeking a more drastic change and are committed to the crossbreeding route, he says the next step for them is to choose the right breed.
"That's when the difficult bit starts," says Mr Winters, citing a wide range of choices for Holstein breeders, including the various continental and Scandinavian 'reds' to the traditional Friesian, Ayrshire, Shorthorn and Channel Island breeds.
"My recommendation is that they only consider using breeds that have a well structured, large enough population and are running a breed improvement and progeny test programme," he says. "And it will also help if they participate in independent international evaluations - through Interbull - to provide a UK basis for comparison."
But identifying a point at which the system falls down, he observes that any evaluation is only of use when it is used within breed.
"It is currently impossible to genetically compare between breeds, such as a Friesian with an Ayrshire or a Shorthorn with a Montbeliarde," remarks Mr Winters, "because we do not yet undertake across-breed evaluations.
"This is simply because we haven't had enough recorded crossbred animals on which to base a genetic evaluation," says Mr Winters, "but now that the UK's crossbred population is growing, DairyCo breeding+ is working on across-breed evaluations and plans to have them in place in 2010.
"But for the time being, genetic comparison between breeds remains an extremely difficult judgement to make and cannot be done with accuracy.
"In the face of this, I'd urge breeders not just to be swayed by semen salesmen, but also to talk to other farmers about their successes and failures."
The choice of bulls is inevitably one of the keys to success of any crossbreeding programme and is considered to be even more important than the choice of breed.
"I believe there's a tendency for caution to be thrown to the wind once a new breed is chosen, but all the principles of good genetic selection must continue to apply," says Mr Winters. "It's important to choose the best bull to meet the goals you have identified and not simply assume that any bull of your chosen breed will bring you the desired benefits.
"For example, using the best Ayrshire bull on an average Holstein herd is unlikely to cause a big production loss, but using an average Ayrshire bull on a top Holstein herd may give rise to an unacceptable drop in milk production.
"Equally, a breed has to be chosen for the second generation and this would typically involve alternating between two breeds, or bringing a third breed into play and using them each in sequence."
Hybrid vigour or heterosis - the mechanism through which the progeny of two different breeds perform better than their parents' average performance - is often cited as a further benefit to crossbreeding, but these benefits in the dairy industry have often been exaggerated, according to Mr Winters.
"Heterosis is a bonus, but it certainly shouldn't be the main reason for going into crossbreeding," he says. "The benefits are relatively small, and they are mainly seen in the first cross generation, but diminish somewhat thereafter, and are not passed down the generations.
"Furthermore, when one breed is far ahead of another for any given trait, hybrid vigour is unlikely to raise the progeny's performance up to that of the best parent.
"This is unlike the situation in the pig and poultry worlds, where hybrid vigour can raise progeny performance beyond that of two comparably high-performance breeds of parent."
Equally, others cite fears of inbreeding as a reason for
crossbreeding, but Mr Winters feels these fears have also been
"Inbreeding is not a significant problem within the UK Holstein population and there is plenty of scope to avoid it through the right within-breed choices," he says.
Other considerations include the loss of pedigree status; a potential reduction in milking herd valuation; the market for surplus heifers; and the impact on cull and calf values, which 'could be positive or negative depending on your choice of breed'.
"Record keeping will also need to be spot-on," adds Mr Winters, "as poor sire identification will not only impact on your own future breeding decisions, but also on national genetic evaluations as they come into play."
But once a decision has been made to crossbreed, there will be around three years before its impact begins to be felt, and many more years before its influence dominates the herd.
"As with all breeding decisions, you have to think long-term when it comes to crossbreeding," says Mr Winters. "Think about how you would like your herd to look in 10 years' time, and consider too the political and economic environment in which you will farm.
"Will there be constraints on production? Will environmental concerns limit stocking density? And will your future milk buyer offer the same milk quality premiums that you currently expect?
"These are difficult questions to answer, but they need careful consideration before major changes are made in breeding direction.
"There is no doubt that there are plenty examples of producers who are already running a very successful crossbreed operation and for others it might well offer a better alternative than their current breeding strategy.
"However, there are no quick fixes in breeding and crossbreeding is no exception. Good genetics, whatever the breed, is the key, and until the availability of across-breed statistics in 2010, it remains impossible to evaluate how much a gain in one trait will compensate for losses in another. So I reiterate that you should embark on the process with care; choose your bulls with as much consideration as in a pure-bred herd; and remember there is no turning back! The new breed's genes will remain in your herd for generations to come."
Steps to successful crossbreeding
• Investigate underlying management problems
• Identify what you want to achieve
• Decide which breeds are likely to deliver your goals
• Choose the best bulls within the breed
• Don't just rely on semen salesmen but also talk to farmers
• Consider the consequences on your herd over 10 or more years
• Consider long term influences such as future milk markets, quotas and NVZs
Main breed options for UK Holstein breeders to consider are:
• British Friesian
• Brown Swiss
• Scandinavian Red (Swedish, Danish, Norwegian)
Potential gains from crossbreeding on Holstein herd
• Genetic improvements in health and fertility
• Gains through heterosis (hybrid vigour)
• Effect on cull cow and calf value (could go up or down, depending on cross)
• Easier management
Potential negative outcomes from crossbreeding on Holstein herd
• Loss of weight of milk, fat and protein
• Farm management difficulties due to lack of uniformity - especially in transition
• Loss of pedigree status and herd valuation, depending on choice of breed
• Difficult breeding choices after first generation cross
• Once started, there is no turning back - bloodlines stay in the herd for ever