March 27, 2011, by David Schwartz
s the world’s appetite for the lean protein of fish grows, so does the demand for alternatives to traditional fishmeal, the blends of small fish species—including herring, capeli and menhaden—that are being fed to fish in aquaculture farms, where nearly half of the fish we eat originates.
Fishmeal is a major source of protein and oil in the fish diet, and is also used heavily in pet foods, as well as for swine and poultry feed. Looking to address the impending shortage of fishmeal, the U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS) has been working to develop fish feeds that minimize or don’t include fishmeal, in order to support sustainable aquaculture.
ARS fish physiologist Dr. Rick Barrows and his team of scientists are investigating ingredients for fishmeal replacement that include plants, animal processing products, and single-cell organisms like yeast, bacteria, and algae.
Dr. Barrows, who received his Masters and PhD in animal nutrition from Iowa State University (“My Masters work was with poultry, but my PhD was with fish,” he says.) spent 15 years with the U.S. Fish and Wildlife Service, developing diets for a variety of species and overseeing different feed manufacturing techniques. He joined the USDA team in Hagerman, Idaho, in 2004, as a nutritionist to develop alternative diets for trout and other species.
We spoke with Rick recently about the intersection between the aquaculture and algal industries.
Can you give us some basic understanding of fish feed—what is desirable, what is to be avoided?
Since the beginning of aquaculture farms, fishmeal—wild, harvested fish—has been the main feed ingredient, comprising up to 60 percent of the diet. Fishmeal is a highly digestible ingredient that’s very palatable, so it’s easy to formulate a diet with a lot of fishmeal in it. Forty years ago there was a lot of fishmeal around and not that much demand.
As aquaculture has grown and as the poultry and swine industries have grown, so has the demand for fishmeal. But when people started to reduce the percentage of fishmeal in aquaculture and animal diets, and substitute other ingredients, some difficulties developed.
So that’s the reason for the ARS Project that we’re working on. It’s part of our role at the USDA to work with industry to the benefit of the American consumer, and to try to commercialize new products and increase the efficiency of the aquaculture industry.
What is the Alternative Feeds Initiative?
In November of 2007 the USDA and the National Oceanic and Atmospheric Administration (NOAA) launched the Alternative Feeds Initiative to accelerate development of other feeds for aquaculture. The initiative’s purpose is “to identify alternative dietary ingredients that will reduce the amount of fishmeal and fish oil contained in aquaculture feeds, while maintaining the important human health benefits of farmed seafood.”
The project was designed to take input from the public—from both pro and anti-aquaculture people—of what they felt was wrong with the aquaculture industry and feeds, in particular, and try to figure out a way forward.
Prior to that there is a group called Plant Products and Aquafeeds, or PPA, a group of scientists that got together with pretty much the same objective, to find alternatives to fishmeal.
Tell us about your spirulina research with respect to fish feed.
I’ve been putting spirulina in fish diets for close to thirty years. I’ve usually used it as a pigment source, or a chelated trace mineral source, with inclusion levels of 2-3% of the diet. But in the last couple years working with Carbon Capture Corporation, when they had large quantities available, we started investigating it as a protein source, with much higher inclusion levels.
How do you determine its value as an ingredient?
We’ve got a 5-step process in evaluating all ingredients. First, we look at the compositional analysis. That is, the level of nutrients and anti-nutrients—if they’re known—in that particular ingredient. The second step is to test palatability, or the effect of that ingredient on feed intake. We don’t want to do a growth study only to find out they won’t eat that new ingredient.
Each of these steps can result in a go, no go, situation. Compositional analysis sometimes can throw an ingredient out. Palatability can also throw it out.
The third step is digestibility. That’s where we determine the percentage of essential nutrients that are available in that ingredient. And this is not a go or no-go situation, but it gives us the information to formulate diets effectively for the growth study. For example, fishmeal has very high protein digestibility, about 95%. And an ingredient that has a protein digestibility of 85% is still good; we just need to put in a little more of that ingredient to get the same amount of protein as the higher digestible source. So it becomes more of a price point issue than a formulation issue.
The fourth step is again a go, no-go situation for industry, which is the effect of that ingredient on the feed pellet quality itself, and on the extrusion process during feed manufacturing. It’s very important for feed pellets to have high durability so they don’t break down during shipping and result in pellets that are uneaten, and thus have low feed conversion ratios and increased costs. Also, the amount of oil that the pellet can absorb is very important. The pellet needs to expand and have equal pore size within the pellet. We call that the functionality of the ingredient.
The fifth stage is of course to do the feeding study and formulate diets where we replace some or all ingredients with a test ingredient and look at growth rate, feed efficiency, and the effect of the new ingredient on organoleptics, or the sensory characteristics, of the final product. That is, does this new ingredient make it taste bad?
And how does spirulina test out?
With spirulina, we’ve looked at digestibility in four species now: rainbow trout, Atlantic salmon, pompano and hybrid bass. We’ve got the Atlantic salmon and the rainbow trout information back. We’re waiting for the other two species. We find good digestibility for all nutrients, which is important. As for palatability, it’s actually a palatability enhancer. I didn’t believe you could do it, but it actually makes rainbow trout eat more. They really like it.
We’ve also seen feed intake increase in the marine species such as white sea bass and yellowtail. When we added the spirulina to a fishmeal-free diet we got growth rates higher than the fishmeal control and the commercial reference diet. So we believe there is some nutrient in spirulina—and we’re not quite sure yet what it is—that is giving fish not only an enhanced growth effect, but also an increase in survival.
How does it compare to other options in price and results?
It’s not competitive at this point, but if the industry can start producing quantities of many tons and get it to a competitive price point, it will be readily accepted into the fish feed world, I believe. It’s going to come down to a cost per protein unit basis.
It’s a nice ingredient. I’ve seen products between 62% and 72% protein, and being that high in protein adds a lot of flexibility to diet formulation.
What other alga are showing promising results?
I haven’t seen any other alga in this kind of quantity. That’s what I really like about Carbon Capture. A lot of algae people call up and say they’ve got algae and we say okay, we need twenty kilos to get started, and they say they have a hundred grams now and can get us a hundred grams next month. That’s not a large enough quantity. If I need five hundred pounds from Carbon Capture, they get it. And you really need to be on at least that scale to get the evaluation done.
The biggest holdup with new ingredients for the fish feed industry is they are concerned about a steady supply of ingredient. They don’t want to work a new ingredient into the formulation and then not be able to get it. So that’s a lot of the concern with algae, until the industry gets big enough to prove that it can support a consistent supply.
I’m looking for ingredients wherever I can find them. At the World Aquaculture Society meeting two weeks ago, in New Orleans, I met three other algae companies who said they had large quantities of products, and we’re going to evaluate those.
What is the aquaculture industry looking for with respect to fish and animal feeds from algae? Are they interested more in the whole biomass, or the residual after the algae is processed for something else, like fuel?
I think there’s interest in whatever product becomes available. Whether it’s a co-product, or a bi-product, or the primary product depends on the person who’s growing it. But if you look at the economics—the oil is the one that always gets me. It hurts when the goal is to have a price point of a dollar a gallon for biodiesel, or oil derivatives, when we’re paying $4.50 to $5 a gallon for fish oil. And if the algae producers could produce an oil that has as much EPA and DHA as fish oil, it would be worth $4 or more per gallon. Why burn it as fuel if you can get that kind of price?
The protein is valuable, too, but there are a lot of other sources for protein. The trouble, though, with the omega-3’s—the long-chain fatty acids—is that right now their only real source is fish oil. Future sources are either going to be algae or genetically modified terrestrial plants, and I think algae will be more readily accepted than the GM oils.
So, if they produced algae that had 30% high omega-3 oils in it, and they expeller pressed it and took 20% away so the resulting biomass had 10% omega-3, with high protein, that would be a wonderful product.
Really what the animal feed industry would like from algae is different products. A liquid oil product would be one. A higher lipid protein product would be another. Or maybe just a high protein low lipid product that would give the feed manufacturers the capability to mix and match different algal sources for different feeding situations.
That’s really the difference in aquaculture versus terrestrial animals. There are over two hundred different aquaculture species being fed. And to come up with one ingredient or one diet for all of them is never going to work.
Anything else that algae producers need to consider in approaching the fish feed market as one of the options for their biomass?
I’ve seen a problem with several ingredient suppliers. Feed manufacturers have their mills set up to handle certain types of products and, for example, a wet product would be very difficult for a standard mill.
The ingredient needs to be flowable. Some ingredients are so flowable—such as spray-dried ingredients—that they’re difficult to handle in bulk. Solar-dried spirulina has a very good consistency. It’s easy to move around without dusting up too much, where the spray-dried spirulina, if you pump that into a giant silo that had a small hole in it, you’d walk into the mill the next day and be knee-deep in ingredient that came out of that small hole. So you want it flowable, but not too flowable.
How does the FDA fit into the future of this and what kind of regulations are you expecting?
The FDA has to approve all new ingredients for animal feeds. The ingredient suppliers need to talk with the FDA and make sure that the ingredient is approved to be fed, or those fish that have consumed it will not be able to be sold. You have to approach the FDA for each species of algae. Dr. John Machado with FDA is the one who is handling ingredients for the aqua feed industry.
In a perfect world scenario, how do you see the growth of aquaculture?
It’s clear that the growth of the aquaculture industry could be hampered by lack of available ingredients, because it has relied so heavily on fishmeal and fish oil. Those supplies are static. We need to find new sources, particularly for fish oil. And I think algal oils and algal proteins are perfectly situated to fill that need to supply the expanding aquaculture industry.
Aquaculture is growing at somewhere between 7% and 9% per year. It’s the fastest growing segment of agriculture. And as other countries become more affluent and buy higher proteins foods, the industry will continue to grow.