Lyso-phospholipids enhance growth performance and feed efficiency in freshwater fish

Lyso-phospholipids, also known as lysolecithin, are produced through the hydrolysis of lecithin, which removes a fatty acid molecule from phospholipid structures. This modification increases their hydrophilicity, making LPLs highly effective emulsifiers. When incorporated into aquafeeds, LPLs disperse dietary fats, increasing the surface area available for lipase action and enhancing nutrient digestion.

As aquaculture expands to meet the growing global demand for fish protein, feed formulations have evolved to include alternative ingredients such as plant-based proteins, reducing reliance on fishmeal and fish oil. However, alternative ingredients often present challenges, including reduced palatability and digestibility, which can result in lower feed intake, inefficient nutrient absorption, and increased waste. While alternative feed ingredients are becoming more common, fish meal is still widely used in aquafeeds, particularly in high-performance formulations.

Differences in the feeding habits of freshwater fish species play a significant role in addressing these challenges. Largemouth bass is a carnivorous fish species, with a natural preference for animal-based protein sources, which makes them more reliant on high-protein diets that closely mimic their natural feeding behaviour. This reliance on protein-rich feeds often necessitates the inclusion of fishmeal in their feed. In contrast, tilapia are omnivorous fish with a natural inclination toward plant-based materials in their diet, enabling them to more readily accept feed formulations that include alternative protein sources such as soybean meal or other plant ingredients.

Despite these distinct feeding strategies, both species face the risk of reduced nutrient absorption and increased waste when feed formulations are not optimized. This is particularly important in freshwater aquaculture systems, where uneaten feed and nutrient waste can accumulate and create environmental challenges due to their closed or semi-closed nature. To mitigate these risks, functional feed additives designed to enhance nutrient digestion, absorption and metabolism have emerged as a practical solution.

ROLE OF LYSO-PHOSPHOLIPIDS AS DIGESTIVE AND METABOLIC ENHANCERS
Lyso-phospholipids (LPLs) are effective digestive and metabolic enhancers due to their ability to improve feed efficiency and growth performance. LPLs, also known as lysolecithin, are produced through the hydrolysis of lecithin, which removes a fatty acid molecule from phospholipid structures. This modification increases their hydrophilicity, making LPLs highly effective emulsifiers. When incorporated into aquafeeds, LPLs disperse dietary fats, increasing the surface area available for lipase action and enhancing nutrient digestion. Additionally, LPLs improve cell membrane fluidity and permeability, further facilitating the incorporation of active nutrients transporters and therefore nutrient transport across the gut epithelium.

Two feeding trials were conducted in freshwater fish species to prove the efficacy of the LPL-based AQUALYSO under different feeding habits and rearing conditions

Trial 1. Efficacy of LPL supplementation in high fish meal feed fed to largemouth bass

A first trial led by East China Normal University aimed to assess the impact of the LPL-based AQUALYSO (0.03%) on the growth performance, feed conversion efficiency, and fat metabolism of largemouth bass (Micropterus salmoides) fed a fishmeal-based diet (Table 1). This research has been recently published in Aquaculture Nutrition (see references).

Largemouth bass juveniles (initial weight: 21.1 ± 1.2g) were divided into four tanks per treatment, with 20 fish per tank. Fish were fed manually to satiety twice a day (8:00 and 17:00 h) for 8 weeks. Water parameters were maintained at a temperature of 27 ± 1°C, pH 7.4 ± 0.19 and dissolved oxygen of 6.0 ± 1.2 mg/L (mean ± standard error).

Results demonstrated that the dietary supplementation of 0.03% AQUALYSO numerically improved the growth and feed conversion efficiency of largemouth bass. Fish fed the supplemented feed showed improvements in growth and feed efficiency by 11% and 5%, respectively, in relation to the control group (Figure 1A and 1B). These improvements highlight the effectiveness of LPLs in maximizing nutrient digestion and utilization even in feeds formulated with high inclusion of marine ingredients. AQUALYSO significantly reduced lipid accumulation in the mesentery and liver, indicating optimized lipid utilization (Figure 1C and 1D). Such effects are critical for maintaining the metabolic health of fish and improving energy availability for growth and feed efficiency.

Trial 2. Efficacy of LPL supplementation in a plant-based feed fed to tilapia reared in low temperature conditions

A second trial was conducted in collaboration with Testing Blue (Spain) to evaluate the efficacy of AQUALYSO (0.025%) supplementation to promote feed intake and growth performance of Nile tilapia (Oreochromis niloticus) fed a plant-based feed (Table 2) and reared at cold temperatures.

Juvenile tilapia (initial weight: 52.32 ± 2.13g), were stocked in 150-L tanks in triplicate, with 16 fish per tank (initial density: 6.6 kg/m3). Fish were fed to satiation twice per day, over 4 weeks. The water temperature was maintained at 17.69 ± 0.58°C to simulate cold stress conditions. Other parameters included a pH of 7.1 ± 0.32 and dissolved oxygen at 9.05 ± 0.13 mg/L (mean ± standard error).

Plant-based feed formulations are less palatable than fishmeal-based feeds, while cold stress further impairs digestive efficiency, reducing feed intake and the ability to emulsify, digest and absorb nutrients. These combined factors can negatively impact fish growth and metabolic health, and fat can accumulate in excess in the liver and viscera due to inefficient lipid utilization. The supplementation of 0.025% AQUALYSO in juvenile tilapia feed resulted in numerical improvements of 10% and 12% in feed intake and weight gain, respectively (Figure2A and 2B). Furthermore, fat deposition in the liver and viscera was reduced by 2% and 3.5%, respectively (Figure 2C), Such effect can help in alleviating metabolic issues associated with low-temperature conditions and excessive lipid accumulation in viscera.

AQUALYSO enhanced fat emulsification and improved nutrient absorption across the intestinal epithelium, allowing fish to extract more energy and nutrients from the feed. This not only supported better growth performance but also reduced fat deposition in the liver and viscera, alleviating common metabolic issues associated with low-temperature conditions. By optimizing feed utilization under these challenging conditions, AQUALYSO demonstrated its ability to maintain fish metabolic health, support energy allocation for growth and mitigate the negative effects of cold stress.

CONCLUSIONS
Results from these trials further corroborate efficacy of the LPL-based AQUALYSO to promote growth performance and health of fish by supporting nutrient digestion, absorption, and utilization. AQUALYSO supports the health, growth performance and feed efficiency in both carnivorous and herbivorous freshwater fish species reared under optimal and suboptimal conditions.

References
1. Bao M., Wang Z., Nuez-Ortín W.G., Zhao G., Dehasque M., Du Z., Zhang M. (2024). Comparison of Lysophospholipids and Bile Acids on the Growth Performance, Lipid Deposition, and Intestinal Health of Largemouth Bass (Micropterus salmoides), Aquaculture Nutrition, 1518809, 13 pages. https://doi.org/10.1155/2024/1518809

About Marleen Dehasque
Marleen Dehasque obtained a Master of Science in Bioscience Engineering at the University of Ghent, Belgium. She has over 30 years of experience in R&D, product management and business development in multinational aquafeed companies. Dehasque has specific expertise in live feed, larval and pre growing nutrition, and feed technology. As an independent consultant, she has supported the development of novel feed ingredients in aquaculture. Since 2019, she is active as Global Product Manager Aquaculture Nutrition responsible for the development and customer support of a diverse portfolio of aquaculture additives, related to Digestive/Metabolic enhancement, Palatability, Feed Quality and Specialty Nutrition.

About Dr. Waldo Nuez
Dr. Waldo Nuez owns a background in aquatic nutrition and health supported by 16 years of combined academic and industry experience. Previously as an academic researcher, his interest revolved around understanding how production strategies and environmental stressors impact growth efficiency, health and product quality, and developing new feeding strategies accordingly. As Product Manager, he was responsible for product strategy, portfolio development and customer support of aqua additives. Nuez holds a PhD in Aquaculture Nutrition from University of Tasmania (Australia), a MSc in Animal Nutrition from University of Saskatchewan (Canada), and a Degree in Veterinary Medicine from University of Zaragoza (Spain). Waldo Nuez is Head of Aquaculture Technical & Scientific Support and leads a team focused on developing innovative and high performing feed additives, and on demonstrating application of nutrition and health solutions in a diversity of species of fish and shrimp.

About Guillermo Bardera
Dr. Guillermo Bardera joined Adisseo’s aqua R&D team as Global Technical & Scientific Support Manager Aquaculture Nutrition. He is home-based in Spain and works under the lead of Dr. Waldo Nuez, Global R&D manager Aquaculture. Bardera holds a PhD in the feeding behavior of Pacific white shrimp (Litopenaeus vannamei), with a particular focus on their response to novel feed additives. His doctoral research, conducted through a joint project between the University of the West of Scotland and Skretting ARC, has received several prestigious awards, including the Nutreco Young Researcher Prize, the Scottish Universities Life Science Alliance Award, and multiple honours from the University of the West of Scotland. Over the past four years, he has served as Study Director at Moredun Scientific, a leading contract research organization specialised in animal health and aquaculture nutrition. In this role, he managed a broad portfolio of research projects for both industry and academia. Guillermo is also an active member of the editorial board for Reviews in Aquaculture, a top-tier journal in the field.