The research, conducted by Jaynos R. Cortes of North Eastern Mindanao State University in the Philippines and Brett Laudato of VDS N.V. in Belgium, set out to evaluate the effects of a dietary additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on growth performance, feed utilization, morphometric condition, growth uniformity, allometric growth, and low-salinity stress tolerance in juvenile P. vannamei. Rather than examining each additive in isolation, the study was designed to assess the overall response to the combined formulation, reflecting how such blends are deployed in commercial feed manufacturing. The team hypothesized that supplementation would primarily enhance nutrient-use efficiency, as reflected by improvements in protein efficiency ratio (PER) and feed conversion metrics, and that these metabolic gains might be associated with favorable changes in growth uniformity, morphometric condition, and tolerance to acute low-salinity stress.

The experimental design was rigorous and controlled. Juvenile shrimp, obtained from White Panther Hatchery in Austria and acclimated in a recirculating aquaculture system at VDS N.V. in Belgium, were stocked at a mean initial body weight of 0.90 grams into 500-liter HDPE tanks, with 80 shrimp per tank. Two dietary treatments were compared over a 42-day feeding trial: a control diet and an additive-supplemented diet, each assigned to four replicate tanks. Both diets were formulated to contain approximately 42 percent crude protein and 7 percent crude fat, ensuring that any observed differences could be attributed to the additive blend rather than to underlying nutritional disparities. The supplemented diet contained choline chloride at 0.30 percent, L-carnitine at 0.05 percent, glycerol monolaurate at 0.07 percent, and lysophospholipids at 0.05 percent. Water-quality parameters, including temperature, salinity, dissolved oxygen, and nitrogenous waste compounds, were monitored throughout the trial and remained comparable between treatments, confirming that environmental conditions did not confound the dietary comparison.

The four additives were selected for their complementary mechanisms of action in lipid digestion, transport, and utilization. Choline chloride functions as a lipotropic factor involved in phospholipid synthesis and lipid transport, facilitating the movement of fats through the body. L-carnitine plays a critical role in mitochondrial physiology, shuttling long-chain fatty acids into the cellular powerhouses where they undergo beta-oxidation to produce energy. Lysophospholipids enhance lipid emulsification and nutrient absorption in the digestive tract, potentially improving intestinal morphology and feed utilization. Glycerol monolaurate has been associated with improved intestinal health and nutrient absorption. Together, these compounds were designed to support the efficiency with which dietary nutrients are digested, absorbed, and converted into growth and maintenance processes, with the potential to reduce reliance on amino acids as energy substrates and thereby exert a protein-sparing effect.

After 42 days, the results painted a nuanced picture. The most striking finding was that dietary supplementation significantly increased the protein efficiency ratio compared with the control treatment, rising from 0.0221 to 0.0237, a statistically significant improvement of approximately 7.2 percent. This was the only significant treatment effect detected among the measured growth and feed-utilization variables. In contrast, survival remained high and comparable between treatments, averaging 93.75 percent in the supplemented group and 92.19 percent in the control. Final biomass, final mean body weight, and final body length were similarly unaffected. The feed conversion ratio was numerically lower in the supplemented group at 1.35 compared with 1.46 in the control, representing an improvement of approximately 7.5 percent, but this difference did not reach statistical significance, likely due to the limited number of tank replicates available for comparison.

Beyond the headline growth metrics, the researchers examined a battery of complementary phenotypic indicators that are often overlooked in conventional aquaculture nutrition studies. Growth uniformity, measured by the coefficient of variation for both weight and length, showed no significant differences between treatments, indicating that the additive blend neither enhanced nor disrupted competitive interactions among shrimp within culture tanks. Morphometric condition, assessed through modified condition factor and allometric growth coefficient, remained unchanged. Length-weight relationships, described by the power function W = aL^b, revealed approximately isometric growth patterns in both treatments, with allometric coefficients of 2.948 for the supplemented group and 3.126 for the control, neither differing significantly from the theoretical isometric value of 3.0. Analysis of covariance detected neither a significant treatment effect nor a significant treatment-by-length interaction, demonstrating that dietary supplementation did not alter the fundamental scaling relationship between body length and body weight.

To probe the physiological resilience of the shrimp, the team subjected ten randomly selected individuals from each tank to an acute low-salinity challenge at the end of the feeding trial. Shrimp were transferred directly into test tanks containing water at 0.35 parts per thousand salinity, a level approaching freshwater conditions that was selected to induce severe osmotic stress and maximize the ability to detect potential treatment-related differences in survival. However, because the challenge water temperature was approximately 14 degrees Celsius lower than the culture temperature maintained during the feeding trial, the shrimp were exposed simultaneously to both osmotic and thermal shock. Kaplan-Meier survival analysis and Cox proportional hazards modeling revealed no significant differences in mortality risk between treatments, with a hazard ratio of 1.34 for the supplemented group whose confidence interval encompassed unity. The authors caution that the combined nature of the stressor means any effects of dietary supplementation on salinity tolerance specifically may have been masked by the concurrent thermal challenge.

Multivariate and exploratory modeling analyses provided converging evidence for the study’s central conclusion. Principal component analysis revealed that the first two principal components explained 75.1 percent of the total variance, with protein efficiency ratio and feed conversion ratio contributing most strongly to the multivariate structure. Tanks receiving the additive-supplemented diet tended to be associated with higher PER values and lower FCR, whereas variation in body condition and growth uniformity contributed to differences among individual tanks regardless of treatment. Standardized path analysis and Random Forest classification, though limited by the availability of only eight tank-level experimental units, consistently identified protein efficiency ratio as the variable most strongly associated with dietary supplementation. These exploratory approaches, while hypothesis-generating rather than confirmatory, reinforce the univariate results and suggest that nutrient-use efficiency may be a more sensitive indicator of dietary additive responses than conventional growth metrics.

The authors acknowledge several important limitations when interpreting their findings. The use of four replicate tanks per treatment, while consistent with many controlled shrimp nutrition trials, limits statistical power to detect small-to-moderate treatment effects. The slight difference in analyzed crude protein content between the experimental diets, 42.06 percent in the control and 42.54 percent in the supplemented diet, cannot be completely excluded as a minor contributor to the observed PER response. Additionally, shrimp used in the survival analysis originated from replicated culture tanks, yet tank identity was not incorporated into the survival models, meaning the stress-tolerance results should be regarded as exploratory. The authors also note that feed intake values represent apparent feed intake derived from cumulative feed allocation rather than direct measurements of consumption, as uneaten feed was not quantitatively recovered.

From a practical perspective, the observed improvement in protein utilization efficiency carries meaningful implications for intensive shrimp production systems. Dietary protein is typically the most expensive component of shrimp feeds, and enhanced protein retention could contribute to reduced nitrogen excretion, lowering the environmental footprint of aquaculture operations. Even modest improvements in nutrient-use efficiency may therefore have both economic and environmental value. However, the absence of significant effects on growth performance, morphometric condition, growth dynamics, and low-salinity stress tolerance indicates that the benefits of supplementation are likely to be subtle and primarily related to nutrient utilization rather than broad enhancements of shrimp performance. The authors call for future studies incorporating longer feeding periods, larger sample sizes, temperature-controlled stress challenges, and factorial or dose-response designs to clarify the mechanisms underlying the observed responses and determine whether improved protein-use efficiency can translate into economically meaningful production benefits under commercial farming conditions.

Subject of Research: Effects of a functional feed additive blend on protein efficiency ratio, growth performance, and stress tolerance in juvenile whiteleg shrimp

Article Title: Effects of functional additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on protein efficiency ratio, growth performance, and stress tolerance in juvenile Penaeus vannamei

Article References: Cortes, J. R., & Laudato, B. (2026). Effects of functional additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on protein efficiency ratio, growth performance, and stress tolerance in juvenile Penaeus vannamei. Frontiers in Aquaculture, 5, Article 1909583. https://doi.org/10.3389/faquc.2026.1909583

Image Credits: AI Generated

DOI: 10.3389/faquc.2026.1909583

Keywords: Penaeus vannamei, whiteleg shrimp, aquaculture, feed additives, choline chloride, L-carnitine, lysophospholipids, glycerol monolaurate, protein efficiency ratio, nutrient-use efficiency, stress tolerance, feed conversion ratio