by Amine Chaabane, Technical & Product manager, Phodé, France
Bringing nature to shrimp feeds:
Shrimp farming has become a ubiquitous industry in the globe today, with different production systems and environments around the world, but yet with similar issues. Most of shrimp’s notorious diseases as AHPND (Acute Hepatopancreatic Necrosis Disease), WSSV (White Spot Syndrome Virus) or EHP (Enterocytozoon hepatopenaei), all originally native to distinct regions in South-East Asia, are now present in several shrimp-farming countries up to South America.
Diseases have proven to be the biggest threat to aquaculture and especially shrimp aquaculture, as the latter do not possess adaptative immunity and thus are not suitable for vaccination strategies at the moment. Prevention and mitigation strategies have been developed, involving:
- Environment control: one of the first steps to prevent intrusion of pathogens in ponds, although depending on farming system – semi-extensive earthen shrimp ponds are not very suitable – and limited, as pathogen are naturally present and ubiquitous in the water
- Antibiotics: known for their efficacy but not preferred because of antimicrobial resistance
- Genetics: pathogen-resisting genetic lines have been developed in the past years, but at the cost of slower growth compared to other lines
- Probiotics: they have become a full part of farm management as environmental conditioners as well as gut and digestive supporters
From the different strategies mentioned above, several of them involve aquafeeds, as the key vessel for active molecules to reach their target, usually gut and hepatopancreas of shrimp. The evolution of the industry led to a significant diversification of specialty feeds where health feeds play an important role in prevention and cure of diseases. But feeds can also be involved in disease causes by not doing their job; an uneaten feed is a perfect source of organic matter for microorganism development, and an important risk especially at high-density farms.
Health solutions need to commit for sustainability
If microorganisms-derived products as yeasts and bacterial probiotics have proven their efficiency and are now used in most of farms and feed mill in the worlds, the need for solutions stimulating natural defenses are still present, especially regarding the diversity of the type of pathogens mentioned above (bacteria, virus, microsporidian parasites).
Among potential solutions, plant extracts have been demonstrating their efficacy on livestock and human health for many years. Known for their antibacterial and antiparasitic activity, as naturally produced metabolites are part of plant defense system against parasites and predators, plant extracts also include some of the most potent antioxidant molecules, and their capacity to stimulate immunity cannot be doubted today.
Apart from their efficiency, plant extracts are also a promising solution as they are sustainable in their natural origin, safe for use at recommended dosages, and can come in several forms.
Phodé Laboratories, experts in functional olfaction and plant extracts; have studied shrimp diseases and its response to design Olpheel Protect, a feed additive composed of synergic blend of plant extracts, to limit the impact of pathogens in shrimp ponds and support shrimp natural defenses.
Effect on disease prevention
To evaluate the effect of Olpheel Protect on disease prevention, an AHPND challenge trial was carried in Vietnam. AHPND is one of the oldest and most common disease in shrimp ponds and can be quickly identified by visual observation of shrimp. For the experiment, specific pathogen free (SPF) whiteleg shrimp (Litopenaeus vannamei), with an average body weight of 1.41 g were tested. An experimental feed was produced with four different treatments tested:
- Negative control : uninfected shrimp fed with control feed
- Positive control : infected shrimp fed with control feed
- Treatment 1 : infected shrimp fed with an Olpheel Protect supplemented feed at 1 g/kg of feed
- Treatment 2 : infected shrimp fed with an Olpheel Protect supplemented feed at 2 g/kg of feed
After 14 days of acclimatation, shrimp were infected with Vibrio parahaemolyticus, at an infection dosage previously established through a separate calibration test.
Survival rate and immune system enhancement were evaluated at three sampling times: 24 hour pre-challenge, 72 hour post-challenge, and ten days post-challenge.
