by H Salehi, E M Ko, N Dang, K Nguyen, B Fronte, R Licitra and R Heavyside
Acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio parahaemolyticus (VP), remains a major threat to Whiteleg Shrimp (Litopenaeus vannamei) culture. As antibiotic use declines due to regulatory pressures and safety concerns, functional feed additives are increasingly recognised as essential tools for disease prevention. Marfeed®, a research-driven functional ingredients brand, has developed a eubiotic product called Gut12. Marfeed® Gut12 – a blend of essential oils, yeast-derived prebiotics and glycerol fatty acid esters – was evaluated in an AHPND challenge trial in Vietnam. Shrimp fed 5g/kg Marfeed® Gut12 showed nearly double the survival of challenged controls (p < 0.05) and exhibited the lowest hepatopancreatic VP loads. These results indicate that Marfeed® Gut12 offers an effective, antibiotic-free strategy to enhance shrimp resistance to AHPND, supporting more sustainable aquaculture production.
Current challenge
Whiteleg Shrimp (Litopenaeus vannamei) represents one of the most widely farmed crustacean species worldwide. Research shows that this species is particularly susceptible to Vibrio parahaemolyticus (VP), the bacterium responsible for acute hepatopancreatic necrosis disease (AHPND). Since its emergence around 2010, AHPND has caused severe economic disruption. Industry analyses report that AHPND led to over US$44 billion in losses between 2010 and 2016 across Asia and the Americas.
The infection specifically targets the hepatopancreas, the shrimp’s central organ for digestion and immunity, causing atrophy, discoloration and rapid mortality. AHPND progresses quickly, with outbreaks typically occurring around eight days after stocking and severe mortality rates – up to 100 percent – within 20 to 30 days. As shrimp farming intensifies worldwide, the threat posed by VP continues to rise, driving the industry toward reliable, non-antibiotic health solutions.
Functional additives as alternatives
The global aquaculture industry is moving away from antibiotic use due to increasing concerns about antimicrobial resistance and food safety. Additionally, many shrimp-importing countries enforce strict inspection protocols and pre-export testing for antibiotic residues, underscoring the need for sustainable alternatives to manage AHPND.
In aquaculture, antibiotics are applied through various methods – oral administration, baths, pond treatments and injections – to prevent or treat disease, with some additionally used as growth enhancers. However, widespread application increases the likelihood that antibiotic residues will remain in farmed aquatic products. Scientific reviews emphasise that managing vibriosis through prevention rather than treatment should be regarded as a key strategy for sustainable shrimp farming.
Formulation and rationale
Marfeed® Gut12 is a formulated blend of immunomodulators comprising essential oils, yeast-extracted prebiotics and glycerol fatty acid esters. Prebiotics derived from yeast cell walls, such as mannan oligosaccharide (MOS) and β-glucan, have been effectively used in various shrimp species to combat Vibrio infections. Moreover, essential oils have demonstrated antibiofilm and bactericidal activity.
This combination is designed to exhibit eubiotic activity, helping to balance gut microflora and support the shrimp gut ecosystem, with the objective of improving survival and growth. This approach aligns with the broader industry focus on feed-based compounds intended for disease prevention rather than treatment.
Controlled challenge study under AHPND pressure
Tables 1 and 2 outline the experimental conditions. The efficacy of Marfeed® Gut12 against AHPND was evaluated in a 27-day controlled challenge study conducted at ShrimpVet’s facilities in Ho Chi Minh City, Vietnam.
Twenty aquaria of shrimp were assigned to one of five experimental groups (Table 1). These were either an unchallenged control, a challenged control or challenged groups fed a diet including Marfeed® Gut12 at an inclusion level of 1.0, 2.5 or 5.0 g/kg feed.
Shrimp were fed their assigned diet for two weeks prior to being challenged with VP. Following challenge, mortality was assessed eight times per day for five days. At 10dpi, the hepatopancreas from three shrimp per aquaria (12 per experimental group) were collected to measure VP load.
| Table 1: Experimental groups | ||
| Diet** | VP challenge | |
| Co- | Standard diet* | no |
| Co+ | Standard diet* | yes |
| Gut12_1 | Standard diet* + 1,0g/Kg Marfeed Gut12 | yes |
| Gut12_2,5 | Standard diet* + 2,5g/Kg Marfeed Gut12 | yes |
| Gut12_5 | Standard diet* + 5g/Kg Marfeed Gut12 | yes |
| *Moisture (9,7%), Crude protein (38,4%), Crude lipid (6,9%), Crude fiber (2,1%), Crude ash (7,9%) ** each diet was administered to 4 replicate aquaria (20 aquaria total) | ||
| Table 2. Experimental diets | |
| Co- | standard diet*, no challenge |
| Co+ | standard diet, VP challenge |
| Gut12_1 | standard diet, VP challenge, 1.0 g/kg Marfeed® Gut12 |
| Gut12_2.5 | standard diet, VP challenge, 2.5 g/kg Marfeed® Gut12 |
| Gut12_5 | standard diet, VP challenge, 5.0 g/kg Marfeed® Gut12 |
| * Moisture (9.7%); Crude protein (38.4%); Crude lipid (6.9%); Crude fiber (2.1%); Crude ash (7.9%) | |
Results: Clear survival and pathogen-load benefits
Figures 1 and 2 show that Marfeed® Gut12 improved survival in challenged shrimp, particularly at the highest inclusion level. Shrimp fed 5.0g/kg Marfeed® Gut12 achieved approximately 29 percent survival under AHPND challenge – nearly double the survival observed in the challenged control group (approximately 12%), with statistical significance (p < 0.05).
In parallel, these shrimp exhibited the lowest VP loads in the hepatopancreas, indicating improved suppression of the pathogen and better protection of this critical organ. Lower inclusion levels showed intermediate responses, suggesting a dose-dependent effect. These findings support the hypothesis that combining multiple immunomodulatory compounds can enhance resilience against AHPND.
Practical implications for shrimp farmers
For shrimp producers operating under increasing regulatory and market pressure to eliminate antibiotics, feed-based immune enhancers offer a practical pathway forward. Key to success is integration. Functional additives such as Marfeed® Gut12 are most effective when incorporated into well-designed feeding programs supported by strong biosecurity, consistent water quality management and early disease diagnostics.
From a practical standpoint, antibiotic-free production systems benefit from proactive nutritional strategies that stabilise gut health before pathogen pressure peaks – often within the first few weeks after stocking, when AHPND outbreaks typically occur. The use of immune-supporting feeds during these high-risk periods can contribute to improved survival and reduced economic losses.
A feed‑based strategy for AHPND management
This study demonstrated that Marfeed® Gut12, particularly at a 5g/kg inclusion level, significantly improved survival and reduced V. parahaemolyticus loads in L. vannamei under AHPND challenge. By supporting gut health and innate immunity, functional additives of this type offer shrimp farmers an antibiotic-free approach to enhance disease resistance. In the transition toward more sustainable shrimp farming, functional feed additives are increasingly recognised as a component of disease prevention strategies.
