Fish meal has been a staple of livestock diets for decades. Forty years ago, poultry and swine diets used 90 percent of the fish meal produced. Now, those industries use less than one-third of fish meal produced and aquaculture diets use the remaining two-thirds.
Over the years, poultry nutritionists have been able to develop more than 80 alternative ingredients to fish meal that can be used in poultry diets on a least-cost basis.
Unfortunately, aquaculture has only 12 to 15 commonly used ingredients, according to Rick Barrows, a fish nutritionist with the USDA Agricultural Research Service in Bozeman, Mont. “We don’t have the flexibility to substitute like other industries do,” he says.
And that fact is becoming problematic at a time when feed ingredient prices are rising at the same time demand for fish feed is increasing. Fortunately, it appears some promising fish meal alternatives are on the horizon.
Demand from Asia
Aquaculture currently accounts for just over half of the total fish products consumed in the world, and it has grown into a $108 billion global industry. Most of the growth in aquaculture is occurring in Asia, particularly China. In 1970, aquaculture accounted for just one-quarter of the fish consumed in China; now that number is 70 percent.
China is experiencing a 9 percent annual growth in aquaculture production, ahead of the global rate of 6 percent, and well above the U.S.’s annual rate of 3 percent.
To meet that demand, China is not only building more farm ponds but more intensively managing those ponds and feeding fish better.
“Feed is what’s driving aquaculture,” said Ron Hardy, director of the University of Idaho’s Aquaculture Research Institute at Hagerman.
Asian farmers who used to feed fish scraps or farm-made feeds are switching to pelleted feeds to meet the growing demand for fish products. Because Asia produces nearly 90 percent of the world’s aquaculture products, that switch is increasing the demand for feed ingredients, especially fish meal.
In the last 40 years, fish feed production grew from less than 1 million metric tons in 1970 to 13 million metric tons. Aquaculture now uses about 5 million metric tons of fish meal annually, up from 1 million metric tons in 1995.
“If we don’t change the amount of fish meal used, we will use everything in the world in four years,” Hardy says.
Another force driving the push to find fish meal alternatives are niche consumer markets. “I believe we will see a whole category of diets based on consumer demand,” he says.
Barrows is working with one producer who wants to feed diets that are formulated without fish meal or fish oil. Bioalgals may meet that target, but could increase the feed cost from $0.50 a pound to $2.50 per pound.
Production systems are also impacting feed formulation. Solids – and how those solids stick together – can create a management problem for producers with re-circulative systems, and these systems are becoming more common on the East Coast and even the Midwest. Norway and Chile are also using more re-circulative systems to grow salmon.
While identifying alternatives for fish meal has been a priority in aquaculture feeds research for many years, Barrows said the problem is actually greater than that. “We don’t just need alternatives for fish meal,” he explains. “We really need more good ingredients."
Barrows and his team have evaluated many ingredients with potential over the last seven years and many more are scheduled for 2012. He uses a six-step process to evaluate all ingredients. It’s a process that frustrates some suppliers who claim their product is the silver bullet the industry is searching for, but there are so many companies hawking alternative products – from biofuel algae to "insect meals” – to the aquaculture feed industry that he had to formalize the process.
“All of these ingredient suppliers see the void from fish meal,” he says. Many want to rush straight to feeding trials, but Barrows begins by looking first at the compositional analysis to identify both nutrients and anti-nutrients in the ingredients. Soy meal, for example, is high in protein but can cause enteritis in fish.
Palatability and digestibility of the alternative are also considered. “If a trout won’t eat an ingredient, a salmon won’t even be in the water with it,” Barrows says. Digestibility is evaluated by the amount of nutrition the fish derive from the ingredient.
Functionality is also a priority. How does the ingredient affect the feed manufacturing process? How much energy does it require to make the feed? Camelina, for example, holds promise for fish diets but is sticky and can gum up the pelleting process. Paying less for a raw ingredient that will cost the feed manufacturer considerably more to pellet won’t benefit feed mills or aquaculture producers.
Ingredients that pass the analytical tests are included in fry feeding trials to screen those with potential from the rest. Then, and only then, do rigorous feeding trials begin. Barrows compiles his data through the USDA ARS Trout-Grains Project website.
Alternatives from biofuels
Many of the alternatives Barrows and his team are evaluating are byproducts from the biofuels industry. Biofuel algae, ethanol yeast and high protein dried distillers grains are all showing potential.
“We need these alternative feed ingredients, it’s the only way we're going to get around these volatile feed prices,” says Wendy Sealey, a researcher with the U.S. Fish and Wildlife Service. “But we need to know what’s in it.”
Her research efforts have focused on calculating how much of each component in these alternatives are actually available to trout. “The numbers by themselves don’t mean much,” she says. “We need to know how much is available to trout.”
Zinc and copper are naturally high in fish meal, and researchers are learning how important those micronutrients are to aquaculture production. Micronutrient deficiencies are often the reason why a fish fed a plant-based diet does not perform as well as one fed a fish-meal based diet.
Importance of phosphorus
Researchers are also finding that phosphorus is more important than once believed. One advantage of feeding fish a grain-based diet is that it reduces the amount of phosphorus in the fish waste, and can help aquaculture producers meet their water pollution goals. But, grain-based fish diets can also cause the fish to have diarrhea, which makes removing fish waste from water more difficult. Feeding dried distillers grains may be a way for aquaculture producers to add phosphorus back to the diet in a form that is more digestible by the fish to meet the fish’s nutritional needs without fouling water supplies.
For all of the research going into developing new ingredients for the aquaculture feed industry, Barrows says the ideal fish feed is really quite simple to describe: “It’s whatever is cheapest and that the fish will grow the fastest on.”