In the last post, we covered two basic concepts about crossbreeding and how it works – the ideas of complementarity and hybrid vigour. If you missed it, you can read more about them here.
Or, if you’d just like a quick recap:
- Complementarity is the idea of mixing breeds that complement each other so that the strong points of one breed offset the weaker characteristics of another. It’s about infusing desirable traits into an animal, while reducing the impact of negative traits.
- Hybrid vigour (or ‘heterosis’) is the bonus in performance obtained when joining two different breeds. The degree to which a trait benefits from this depends on its type, with longevity and functional traits benefiting more than production ones.
So, what do we have to keep in mind when we implement a crossbreeding program, and how do we address drawbacks while maximising benefits?
The most important thing to consider when going to crossbreeding is that parental performance still matters.
The gain from hybrid vigour is minor compared to the gain from using high genetic merit semen, and should be considered a bonus rather than the end game. The outcome of joining two poorly performing parents is a poor performing heifer – yes, even including the bonus to parental average. Crossbreeding is not a good reason to keep the offspring from natural service bulls. It should be part of a proper breeding plan, using semen of high genetic merit.
Semen selection could be a whole blog post in itself, but let’s keep it very simple for now: ADHIS produces a catalogue of all the best bulls currently available with Australian data. You can see the latest Good Bulls Guide here. These bulls are the ones which are most profitable under Australian conditions. If your bull is in there, chances are good that you’re on to a winner.
The second thing to note is that as you keep joining crossbred offspring back to the original breed sires, the bonus from hybrid vigour wanes. These cows are no longer as genetically dissimilar from the two parent breeds, containing genetic information sourced from both population pools. Therefore, the extra gain you achieve from mating two animals from very different sources is consequently reduced.
Farmers have developed different crossbreeding strategies that can be used to combat this. While there are many ways to pat a cat (there’ll be no skinning kittens on this blog!), there are two popular strategies that seem to currently dominate. A 2-way cross (see the diagrams below for details) will keep heterosis at 67%, whereas a 3-way cross will maintain it at 86%. This does mean that while the additional bonus is smaller than for a first-cross calf, it is still present within the system.
Using the benefits of complementarity and hybrid vigour, crossbreeding can be a great way of improving a variety of traits within your herd. However, as with any management strategy, there are some things to consider before leaping in feet-first.
Firstly, the market tends to favour purebred animals with higher prices and values. If stud animals or export heifers make up a significant part of your business, there’s obviously very little incentive to venture into this system. Or if you’re a farmer looking to exit the industry in a few years and sell your herd, crossbred cows may not be the best way to go.
Secondly, the Holstein-Friesian breed has the most extensive dataset and widest range of sires available – meaning it’s very easy to get ABVs and index results for black-and-white animals. Jersey, Red breeds, Guernseys and Brown Swiss are also supported, but to a slightly lesser extent. As genetic merit is so important, we would recommend choosing a second and/or third breed where production figures and genetic data are widely available – Jerseys and a Red breed tend to be a popular option.
Finally, having a non-uniform herd can have its own challenges. The size of crossbred cows can vary greatly (at least initially – with successive generations, this can be corrected by selective breeding), causing issues in the milking shed with smaller cows standing too far forward to get cups on easily. Calving ease can also be a concern.
Some farmers also simply just enjoy the pleasure of having a uniform purebred herd – aesthetic preferences can be very important for day-to-day enjoyment in farming, and passionate members of breed associations would be rightly offended if told they were ‘doing it wrong’. It’s true that there are many highly profitable purebred herds, just as there are many excellent crossbred ones also. Although complementarity can provide an excellent boost, thanks to natural variation within breeds, it’s still possible for a pure-breeding farmer to improve longevity and fertility by selecting sires that have high ABVs in these traits. It really is all about finding the system that works best for you.
Our next post on crossbreeding will focus on further reading you can do to find out more about the topic. I’ve been getting some great suggestions which I’m compiling into a little library – keep them all coming! I’m also still looking for crossbreeding farmers to talk to, so feel free to put yourselves (or some poor unsuspecting farmer you know) up for a quick interview. I’m sure plenty of farmers would be interested in hearing some Australian-specific experiences and information.