Can plant proteins like sunflower meal prove a viable alternative to soy in animal feed?

20-Sep-2024 - Last updated on 20-Sep-2024 at 13:51 GMT

Soybean meal (SBM) remains a staple in broiler diets due to its high protein content and balanced amino acid profile. However, environmental concerns and a desire to reduce reliance on imports have spurred interest in local alternatives across the EU.

Rapeseed meal (RSM), sunflower meal (SFM), and other plant-based proteins have shown potential as partial replacements for SBM, though outcomes depend on protein levels and dietary adjustments.

Ad van Wesel, feed innovation expert at Dutch feed group ForFarmers, acknowledges SFM's value due to its low anti-nutritional factors (ANFs).

He highlighted though that, in poultry, the potential to increase the use of SFM is currently limited.

In contrast, pigs can utilize sunflower meal and sunflower expeller more extensively due to their ability to handle higher fiber levels and adapt to bulkier feed, he explained.

Advances in sunflower meal processing

“Advances in sunflower meal processing now allow producers to offer meal in different protein fractions—low, medium, and high protein. This technology provides a more consistent and predictable protein content, enabling higher inclusion rates without the risk of variable nutrient levels.

“However, in the Netherlands and western Germany, the relatively high phosphorus content remains a limiting factor. Due to national phosphorus regulations, we must carefully manage the total phosphorus in our formulations for both pigs and ruminants to adhere to these phosphorus ceilings,” van Wesel told us.

A USDA GAIN report from April this year forecast increased use of sunflower meal in animal feed in countries like France, Hungary, and Spain this year, while usage is expected to decline in the Netherlands, Denmark, and Poland.

The authors stressed the competitive edge that sunflower and rapeseed meals have in that they are exempt from the EU Deforestation Regulation (EUDR). The growing demand for non-GMO feed could further boost sunflower meal consumption in the EU, they added.

The authors also outlined how Russia's invasion of Ukraine in February, 2022 had a major effect on global markets, particularly the sunflower sector. As a key supplier to Europe, Ukraine plays a crucial role in the sunflower products market.

Replacing soy in broiler diets

Recent research undertaken at Texas A&M University, and published in Poultry Science, evaluated the complete replacement of SBM in broiler feed with a combination of rapeseed meal, sunflower meal, cottonseed meal (CSM), potato protein, pea protein, pea flour, and corn gluten meal, supplemented with synthetic amino acids, enzymes, and probiotics. The study found this approach maintained optimal growth, feed conversion ratios (FCR), and feed intake comparable to traditional SBM-based diets.

Leon Marchal, innovation director at IFF Health & Bioscience, and co-author of the study, told us these results exceeded expectations.

“Our study indicates that SBM can be completely replaced without significantly affecting poultry performance, achieving a cost outcome comparable to soy-based diets as well as aligning closely with breeders’ goals.”

He emphasized that precise formulation and the right combination of feed additives are key to ensuring soy-free diets do not compromise performance.

“We are seeing a small number of producers aiming to go soy-free in broiler production, as well as others looking to reduce soy inclusion levels while maintaining performance. Typically, removing soy impacts both performance and economics, but we wanted to push the boundaries of current research to find the optimal way to replace SBM using a combination of strategic approaches.

“Our focus was on finding the right mitigation strategies, including feed additives, to ensure the bird can perform at its best. We aimed to identify the most effective use of enzymes, probiotics, and other supplements to make soy replacement as efficient as possible. Along with phytase, we incorporated enzymes like xylanase, β-glucanase, and protease to help young birds digest less digestible raw materials effectively.

“Soy-free diets present challenges, particularly in terms of fiber content and the balance of synthetic and total amino acids, both of which are much higher compared to standard diets. Additionally, we had to address the drop in potassium levels that comes with soy removal. While lower potassium can improve litter quality, going too low can cause problems, so we ensured that the electrolyte balance remained stable.

“Ultimately, we crafted a diet that maintained performance while replacing soy, demonstrating that a carefully formulated mix of synthetic amino acids, enzymes, and probiotics can help overcome the challenges of soy-free broiler diets," said Marchal.

Aqua feed innovation

Sunflower meal, when fermented, is showing promise in aquaculture.

Margareth Øverland, a professor in aquaculture nutrition at NMBU and the Center Director of a Center for Research-based Innovation (CRI), Foods of Norway, led research evaluating the use of fermented sunflower meal in diets for Atlantic salmon under commercial-like farming conditions. Aller Aqua formulation experts were also involved in the work. The study was published in Aquaculture.

GettyImages-1146294272 — The Norwegian research shows fermented sunflower meal, at a moderate inclusion rate of up to 10%, could be a suitable protein source for Atlantic salmon diets under commercial-like field conditions in the grow-out phase in seawater. Photo credit: GettyImages/DieterMeyrl

“Sunflower meal is used in aquafeeds but often has high fiber content, reducing its suitability for fish feed. While it contains some ANFs, the main concern is the fiber. We aimed to assess how fermentation technology could improve the nutritional value of SFM under field-like conditions.

“We know that by using solid-state fermentation with microbes, we can reduce the fiber in plant proteins, liberate the nutrients bound to the cell wall, increase their availability, and lower antinutritional factors. Additionally, this process can generate bioactive components, which may enhance health.

“In our trial, we evaluated the fermented SFM at two locations—one in a fjord and the other in a coastal area—where fish were exposed to varying environmental conditions and pathogens. We observed high growth performance, improved health, along with a reduction in gut inflammation and a reduction in the number of distal intestine ectopic goblet cells in the fish fed the fermented soybean meal, despite challenges such as an outbreak of Pancreas Disease and also Pasteurella spp at the fjord location and an outbreak of Pasteurella spp at the coastal site. Their gut microbiota also showed an increase in lactic acid bacteria, which could be linked to bioactive components, such as flavonoids, known to support immune responses and protect against oxidative stress,” she told us.

Solid-state fermentation is a promising method to enhance the nutritional value of plant proteins and reduce their adverse health effects. This biorefinery process, using minimal liquid and microorganisms like bacteria, yeast, or fungi, breaks down indigestible polymers from agro-industrial residues into simpler sugars, releasing digestible nutrients. It can increase the dietary inclusion of alternative plant proteins by reducing fiber and ANFs and by improving protein digestibility.

Sunflower meal is cheaper than soy protein concentrate and is locally produced in Europe, aligning with the region’s push for sustainable, local feed ingredients, added Øverland.

“However, more work is needed to optimize the fermentation process, identify the best microbes for different substrates, and reduce drying costs. We also need to investigate the mode of action of these bioactives, including flavonoids, to understand their role in the positive effects observed. Access to research funding would be crucial to continue this important work,” she remarked.