by Dr Scott Tilton, Julia Green & John Hagios, The Andersons, Inc., USA
Efforts to reduce global warming are resulting in continued increases in the global production of biofuels such as ethanol from corn on a global basis. Historically ethanol production resulted in the production of distillers dried grains with solubles (DDGS), and potentially distillers corn oil as their animal feed co-products. However, a little over a decade ago the United States ethanol industry started to install mechanical separation technology to physically separate residual protein from fibre to create improved animal feed products. Today, there are seventeen plants in North America producing a product that the industry is referring to as fermented corn protein.
Fermented corn protein benefits
The term fermented corn protein (FCP) is being used to identify distiller dried grains that are above 48 percent crude protein on an as fed basis. Additionally, these products are typically going to be much higher in inactive yeast from the fermentation process than traditional distillers’ grains, often making up approximately twenty percent of the product by weight, compared to five to six percent yeast content of traditional DDGS. This increase in yeast content is due to yeast travelling with the protein fraction during the separation process when fibre is removed.
Secondary benefits of the increased yeast concentration are improved amino acid profiles compared to ingredients like corn gluten meal, as it contains about 80 percent more lysine, 55 percent more tryptophan, and 30 percent more arginine than corn gluten meal even though FCP only contains 50 percent protein compared to typical U.S. corn gluten meal which contains 60 percent protein.
Fermented corn protein also has key advantages to offer when compared to soybean meal, as it is slightly higher in protein (50 percent vs 46.5 percent to 48 percent).
In addition, corn is inherently high in sulphur containing amino acids such as methionine and cysteine. As such fermented corn protein has about 50 percent more methionine, and 35 percent more total sulphur containing amino acids than soybean meal.
Compared to many of the novel proteins entering the aquafeed market like single cell proteins and insect larval meals, fermented corn protein also has the advantage of scalability, as there is well over a million tonnes per year being produced through the combined efforts of seventeen ethanol plants in North America.
FCPs in Pacific White Shrimp
Due to the decreased fibre content, and high protein content of these fermented corn protein products, they have become widely used in aquaculture diets for a variety of species ranging from Atlantic Salmon to Pacific White Shrimp.
Extensive research has been conducted with 50 percent protein fermented corn protein products in Pacific White Shrimp with studies consistently showing equal or better growth performance and survival rates when replacing a variety of more expensive ingredients at up to 18-20 percent of the diet.
Initial research with fermented corn protein was conducted by Qui et al., 2017, who evaluated the product in a series of three experiments either as a replacement for soybean meal, or a combination of soybean meal and fish meal. Their work found that up to 30 percent FCP could be used in diets when replacing soybean meal only (Table 1), but when replacing a combination of fish meal and soybean meal only 18 percent FCP could be used before growth was reduced (Table 2). This likely indicates that a minimal amount of fish meal is required with current formulation technology.
Replacing Other Ingredients
Subsequent research has focused on replacing ingredients other than fishmeal Nazeer et al., 2022 evaluated feeding up to 20 percent fermented corn protein in replacement of corn protein concentrate with no significant differences in growth, feed conversion, ratio, or survival rates.
More recently the work of Nguyen et al., 2024 evaluated replacement of a combination of Menhaden fishmeal, soybean meal, and corn protein concentrate in a green-water production system. Diets contained zero, five, 10, 15, 20 or 25 percent of the 50 percent protein corn fermented protein product. This was accomplished by reducing inclusion rate of fish meal from 6.0 percent for the control diet to 4.8 percent, 3.6 percent, 2.4 percent, 1.2 percent and 0 percent with increasing FCP product inclusion.
Similar approaches were used with soybean meal 50.5 percent, 49.3 percent, 48.1 percent, 46.9 percent, 45.7 percent and 44.5 percent inclusions and for corn protein concentrate (Empyreal 75) 7.5 percent, 6.0 percent, 4.5 percent, 3.0 percent, 1.5 percent, and zero percent inclusions, respectively. Corn starch and soybean oil inclusions were adjusted to keep diets iso-nitrogenous and iso-lipidic. No differences in survival rate, average final weight, or feed conversion ratio were observed during the eight-week study. Final weights ranged from 17.86 to 18.56 g per shrimp (Figure 1).
Product availability
With over a million tonnes of product available annually, corn fermented protein has the scale to be utilised in today’s aquaculture rations. It is available for purchase in most areas of the world, and can be shipped in bulk via truck, rail, or container. By combining product from multiple production locations, it may even be possible to fill a hold on a vessel. These products are marketed with the corn distillers dried grains (DDG) feed ingredient definition in North America, and when shipped internationally it fits under the same Harmonized Tarriff Code as traditional distillers feed products.
Summary
While a recent entrant in the high protein ingredient market, FCP volumes have reached a point where they are a viable alternative ingredient for use in shrimp and other aquaculture diets. They are high in inactive yeast content, resulting in a vastly improved amino acid profile compared to conventional distillers dried grains with solubles (DDGS). Multiple studies have shown that use of FCP to replace higher cost proteins or fishmeal have no impact on growth rates and has resulted in significant commercial interest in the use of the product.
Published in the October 2024 issue of International Aquafeed.
