14 Oct Health functionalities in shrimp feeds: Connecting science with field reality
Jean-Benoît Darodes de Tailly, Thomas Denis, Phileo by Lesaffre
The progressive intensification of shrimp production systems, driven by a growing market demand and land constraints, has inadvertently created ideal conditions for pathogens to thrive. The shrimp industry contends with a wide range of pathogens, including bacteria, viruses, fungi, and parasites which are often associated with intricate disease dynamics and symptoms, making diagnosis complex and treatment costly.

There are also no effective treatments against some of the most important shrimp pathogens such as the white spot syndrome virus and Enterocytozoon hepatopenaei (EHP) which can lead to unpredictable harvests and significant financial losses. Given these challenges, there is growing interest in preventive strategies that enhance shrimp’s natural defense mechanisms and improve their ability to cope with the conditions that may promote disease outbreaks.
Feeds that go beyond nutrition: Function or fiction?
The reality often shows that despite investments in high-quality feed, disease-free post-larvae (PL), water disinfection, and other biosecurity measures, pathogens continue to infiltrate shrimp farming systems through various means. Once pathogens enter a farm, their rapid spread can be exacerbated by the warm temperatures required for shrimp farming and the aqueous environment, which is an ideal medium for pathogen transmission and multiplication. Shrimp sensitivity to pathogens stems from a variety of inherent characteristics. For instance, shrimp naturally inhabit the pond bottom, constantly coming into contact with substrates and potentially pathogenic microorganisms. Regular molting also makes shrimp more susceptible to infections and parasites during this critical period. Additionally, and unlike mammals and some fish species, shrimp lack an acidic stomach barrier that could offer protection against pathogen entry.
Concurrently, the shrimp industry has gradually shifted towards more intensive practices. The higher densities and frequent variations of water quality encountered in such systems, together with adverse conditions exacerbated by the effects of climate change, can be important vectors of stress and compromised immunity further adding to the susceptibility of shrimp. Jiang et al. (2005) demonstrated that suboptimal oxygen concentrations could lead to notable decrease in haemocytes, the shrimp’s primary immune cells. Similarly, Wang and Cheng (2005) found that abrupt salinity shifts could also compromise shrimp immune defenses within hours, favouring Vibrio alginolyticus infection (Figure 1). Once infected, shrimp have limited adaptive immune responses, and no commercial vaccines are currently available to protect them against future infections.

This situation has led farmers to increasingly rely on functional additives by manually top-coating them onto commercial feeds during their culture cycles. While this method has been effective in managing disease outbreaks, directly incorporating additives into the feed formulation offers a more reliable solution. It ensures precise dosage and consistent mixing, and minimizes the risk of water leaching of additives allowing for lower inclusion rates with the same effectiveness. Additionally, this approach simplifies administration, reduces the risk of fraudulent or low-quality additives entering the farm, and provides feed manufacturers with an opportunity to convert farmers into consistent users of functional feeds. With the professionalization of farm management practices over the past decade, there is now greater potential for developing advanced, measurable functional feed concepts, provided there is a solid understanding of the physiological mechanisms required to achieve the desired outcomes.
Pathways to immunity
Unlike many other farmed animals, our understanding of the shrimp immune system remains rudimentary. The existing knowledge is scattered across a wide range of literature, which can be confusing and present limitations for developing effective functional feed concepts.
In practical terms, shrimp natural defenses comprise three main barriers, each of which can be actionable with the right approach. The first barrier is the overall physiological and antioxidant status, which involves maintaining cellular health and mitigating oxidative stress caused by reactive oxygen species. This ensures robustness and less susceptibility to an infectious event. The second barrier is the epithelial layer, which serves as a physical barrier. This barrier includes the shrimp’s cuticle, gills, gut lining, mucus and microbiota. Maintaining the integrity of the epithelial layer effectively prevents pathogens from entering the body cavity and spreading within the shrimp. If pathogens evade these initial defenses, the immune system forms the third and final barrier. The immune system of shrimp relies on innate responses mediated by haemocytes – the shrimp’s immune cells. These cells coordinate and execute various humoral and cellular defense mechanisms that work together to control and eliminate pathogens.
Strategic interventions can be implemented to support and optimize these three barriers. Antioxidants are regularly utilized to block oxidative chains and the excessive production of free radicals. Bioactive compounds and probiotics can be incorporated into feeds to improve gut health and integrity by acting against pathogens and reinforcing the barrier it forms with the external environment. Immunostimulants are also commonly used to boost the production and activation of immune cells, enhancing immunity by fortifying both its cellular and humoral components.
While these strategic interventions are not silver bullets against pathogens in shrimp farming, they remain an important part of an integrated management approach that helps mitigate infection risks and severity. They should be viewed as complementary tools within a broader strategy that includes good farming practices, biosecurity measures, and regular monitoring, as described in Figure 2.

Benefits of integrating health & robustness in feed development
Developing a shrimp diet is a complex process that involves considering the nutritional needs of shrimp at different life stages, selecting appropriate raw materials, and optimizing the physical parameters of the pellets. The goal is to create effective diets at minimal cost while ensuring consistent performance.
The industry typically evaluates diet efficiency using parameters such as feed intake, growth, feed conversion ratio (FCR), and cumulative mortality. However, moving forward, it’s essential to also consider the other benefits of specific diets on a broader range of parameters, particularly those related to health. This is crucial because, while achieving low FCR through high-quality feed is important, disease outbreaks can have a much more severe impact on farm economics at harvest. Table 1 illustrates this by modeling the effects of changing FCR and/or survival rates on an average L. vannamei farm in Vietnam. Unfortunately, assessing diet performance is often constrained by limited resources, and health considerations are not always prioritized. However, these can often be addressed cost-effectively with the right functional approach.

Effectiveness of tailored functional feeds
To illustrate the value of this approach, Phileo by Lesaffre conducted a large-scale commercial trial to evaluate the effectiveness of tailored functional feed concepts. These concepts, developed and validated under laboratory conditions, were tested to determine their impact on economic performance in real farming conditions. The trial was carried out in a cluster of corporate farms near Guayaquil, Ecuador, covering 101 hectares of commercial shrimp ponds and compared the performance of shrimp fed with a functional diet against those fed with a conventional diet over a full culture cycle.
The functional feed included Safmannan®, a yeast postbiotic from Phileo by Lesaffre, rich in beta 1.3 – 1.6 glucans and mannans, and Selsaf®, Phileo’s organic selenium-enriched yeast. These components were blended synergistically to support the three primary health barriers previously discussed in this article. Both solutions were incorporated into the feed at dosages of 0.5kg (Safmannan®) and 0.1kg (Selsaf®) per ton of feed, to mitigate the potential negative effects of pathogenic threats and oxidative stress.

The inclusion of Safmannan® and Selsaf® resulted in an increase in survival rates from an average of 50.3% in the control group to 54.3% in the supplemented group (Figure 3A). Given the absence of any clear infectious events during the culture cycle, moderate improvements in survival could be expected. Nonetheless, FCR improved substantially from an average of 1.78 in the control group to 1.60 in the supplemented group (Figure 3B).
Although no specific health parameters were recorded during production, this improvement in FCR is likely due to an overall enhancement in the health status and gut health of the shrimp throughout the production cycle. Consequently, production costs decreased from an average of USD 4 per kilogram of shrimp in the control group to USD 3.6 per kilogram of shrimp in the supplemented group. This cost reduction resulted in an increased profit margin of USD 409 per hectare. The proposed solution hence yielded USD 100 of returns per ton of feed, for an initial investment of USD 4 per ton of feed for both functional additives, equivalent to an ROI of 1:25.
A guide on functional additives
These results highlight the substantial performance gains achievable through functional feed concepts, even in the absence of clear pathogenic threats. They also demonstrate how improved health can enhance the nutritional performance of conventional diets under commercial conditions with minimal investment in the formulation.
To support shrimp producers in implementing functional solutions, Phileo by Lesaffre developed Aquasaf Shrimp, a comprehensive program offering practical guidance on using fermentation solutions to improve health mechanisms and performance of shrimp.
This program is built from a decade of research and development in yeast and bacteria, probiotics, and postbiotics. It features case studies conducted with numerous institutes and commercial partners around the globe and integrates results from relevant published papers. A detailed user manual accompanies the program, and can be downloaded using the QR code or https://phileo-lesaffre.com/en/program-aquasaf-shrimp/

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