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Wednesday, February 11, 2015

11/02/2015: Aquaculture View

by Dominique P Bureau, member of the IAF Editorial Panel

First published in International Aquafeed, January - February 2015


Meaningfully comparing the efficiency of different animal productions?

Back in October 2014, I attended the World Nutrition Forum (WNF) organised by Biomin in Munich, Germany.  Several times during this very interesting forum, the different speakers and participants raised the issue of efficiency in animal food production. One of the keynote speakers, Jørgen Randers from BI Norwegian Business School, told the audience that the broiler chicken would most probably emerge as the “global winner” among all other animal productions with the increasing scarcity of global feed/food resources in sight.
 

http://issuu.com/international_aquafeed/docs/iaf1501_w1/12

Other experts at the WNF contended that aquaculture species due to their low feed conversion ratio (FCR, feed: gain) and low energy requirements, should not be discounted and could well win the ‘efficiency game’, if there was ever one.
We, in the field of aquaculture, are not at our first exposure with this type of debate. My favorite debates are those raised by small (and rich) interest groups based in the USA: “Are we farming the tigers of the sea? Shouldn’t we cultivate thriftier herbivorous or omnivorous fish species (tilapia and carps) rather than wasteful carnivorous species, such as Atlantic salmon?”

Having received academic training in agronomy and livestock production, taught agriculture and animal nutrition courses and studied quite extensively the bioenergetics, nutrient mass balances and macronutrient nutrition of different aquaculture species for the better part of past three decades, I enjoy watching and occasionally contributing to this debate.

How does fish production compare with cattle, pig or chicken production?  How do different aquaculture productions compare? We are often tempted to compare things on the basis of feed conversion ratio (FCR), ie. kg of feed used vs. kg of biomass obtained. However, feeds for different species have different nutritional composition. In general, feeds for aquaculture species are of significantly higher nutritional density (e.g., higher digestible protein, higher lipids, higher digestible energy) than feeds for terrestrial livestock species (beef, dairy, swine, poultry, etc.). Animals also have different market weights and efficiency generally changes quite significant with live weight.

On what basis should we compare different productions then? Energy, macronutrients, carbon footprint? Per kg of live weight or kg of edible product? At a common weight? Over the entire life of the animal or just the productive periods (in the case of a laying hen or dairy cow for example)? Only the edible products or all the waste and by-products properly accounted for?

A few years ago, Dr Katheline Hua (Humboldt University, Berlin, Germany) and I carried out an analysis of the efficiency of a few terrestrial animal and aquaculture species.  We tried to base our analysis on values from published scientific studies that we deemed credible and fairly representative.  We also tried to gather data that were representative of the normal market weight of the animals. Some part of this analysis was already presented in a review paper we wrote with “sustainability” researchers and some industry critics (Reference : Naylor et al., 2009. PNAS, 106, 15103-15110).

Our findings were that of the animals we selected, pigs were less efficient. However, their market weight is also considerably greater than of fish and birds species cultivated today.  Protein and energy-wise today, the broiler chicken does win the efficiency game today.

However, interestingly most aquaculture species are really not far behind.  Genetic improvement played a big role in the efficiency of poultry production. Today, a broiler chicken reaches its market weight (2 kg?) in about 6-7 weeks. With a few minor exceptions, we’ve barely started any meaningful genetic selection efforts for aquaculture species.

Overall, differences between different aquaculture species were not that large. The great differences in FCR we are seeing between species are often a reflection of different digestible nutrient density of the diet, the energy-yielding nutrients used (lipids vs. protein vs. starch) and difference in harvest weights. However, differences do exist and we need to explore the basis of these differences to make progress. We clearly need to invest more efforts in genetic selection.  And I forgot, no Atlantic salmon, rainbow trout are not “less efficient” than “omnivorous” species!

In the big scheme of things, is it at all meaningful to compare efficiency of different animal productions? Do we debate endlessly about the efficiency of traveling to work on foot or by bicycle, motorcycle, smaller or larger car, 4x4 minivan, bus, tramway or train? Our homes and landfills are full of appliances, furniture, clothes, and nick-nacks that all required resources and energy to produce and transport and to operate?

We travel hundreds of kilometers for rest and recreation (R&R) on weekends or to visit a single client during the workdays.  I do not pretend to know the truth or what’s best. To me this is all much too complicated. However, it does worry me a little when the liveliest debate is which of the broiler chicken, Atlantic salmon, common carp or Nile tilapia is the most efficient!  I think we have got bigger things to worry about.

Agree or disagree? Always happy to hear from you. dbureau@uoguelph.ca


Read the magazine HERE.

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This blog is maintained by The Aquaculturists staff and is supported by the
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