The inclusion of SCPs in feed does not affect its attractability to shrimp

Matt Longshaw, Jarin Sawanboonchun, Calysta, Wutiporn Phromkunthong, Nutt Nuntapong, Baranee Bamrung, Prince of Songkla University

The production of shrimp under culture conditions has seen major developments and improvements over the past few decades with a strong focus on the whiteleg shrimp (Litopenaeus vannamei) which is now the most widely cultivated shrimp species. Improvements in cultivation methods, disease diagnostics and management, as well as in seed availability, have been matched with improvements in nutrition and feed quality. Furthermore, the feed industry has strived to reduce its environmental impact by producing balanced feeds with sustainable ingredients and minimal waste.

Calysseo SCPs

One approach of the aquaculture industry more widely has been to look for alternative protein sources to replace fishmeal in whole or in part due to perceived concerns over sustainability and fluctuating costs. This has led to the testing of various protein sources including, but not limited to, various plant and animal protein sources as well as proteins from single cells, such as algae and bacteria (known collectively as singlecell proteins or SCPs).

At the same time, ingredient suppliers such as Calysta have continued to move towards commercial production. FeedKind® protein is a single cell protein fermented from methane and oxygen. With a manufacturing process that uses no agricultural land and little water as compared to traditional protein production, FeedKind stands to accelerate trends in sustainability across the aquaculture industry. Calysseo, a joint venture between Calysta and Adisseo, is on track to commission the first commercial FeedKind production facility later this year in Chongqing, China.

Figure 1. L. vannamei shrimp used to test the attractability of FeedKind® in diets.

Figure 2. Schematic drawing of testing chamber showing acclimation, holding and feeding sections of the maze.

Figure 3. Photograph of staff monitoring shrimp fed diets containing different levels of FeedKind®.

In brief, it is produced at a commercial scale using a loop fermenter, dried using a combination of centrifugation and high temperatures and sold as a feed ingredient under the tradename FeedKind. Closedloop manufacturing can begin to bring the level of consistency and quality to ingredient supply that feed mills have become accustomed to. Primarily composed of the naturally occurring Methylococcus capsulatus, it contains all the essential and non-essential amino acids required by animal hosts.

SCPs attractability

Studies conducted by Calysta have shown that the protein is readily incorporated into feeds with no loss of pellet integrity, is highly digestible, has a high protein content (>70%), and has positive impacts on growth and feed conversion ratios. In addition, it has a positive influence on immune responses in fish and crustaceans and has recently been shown to improve survival outcomes of whiteleg shrimp when exposed to Vibrio parahaemolyticus, the causative agent for acute hepatopancreatic necrosis disease (AHPND), in a disease challenge.

Although our data has shown that the inclusion of FeedKind is not detrimental to feed intake, there have been suggestions that some SCPs may be unpalatable at high levels or may lack certain components, normally present in fishmeal, that improve attractability of feeds to farmed animals and thus potentially reduce feed intake. To address these concerns, Calysta commissioned a study at the Prince of Songkla University in Thailand to test the effect of replacing fishmeal with FeedKind® on diet attractability in whiteleg shrimp.

Materials and methods

Four test diets, each containing around 38% crude protein, and a commercial feed (Gold Advance 852) were tested. The test diets each contained soybean meal, corn protein concentrate and poultry meal as protein sources and either 15% fishmeal and 0% FeedKind (diet 1), 10% fishmeal and 5% FeedKind

Figure 4. Photograph of section of testing maze containing feed and shrimp.

(diet 2), 5% fishmeal and 10% FeedKind (diet 3) or 0% fishmeal and 15% FeedKind (diet 4). Pelleted feeds were produced in-house that contained standard ingredients including binding agents and vitamin and mineral premixes to produce balanced diets. Shrimp, weighing on average 0.5 g (Fig. 1), were acclimated for a week in brackish water and fed the standard diet three times daily. On the day of the trial, 20 shrimps per group were randomly allocated to a rectangular maze system (Fig. 2, 3) and held in the acclimation section for 30 minutes. After this time, 2 g of feed were placed in the feed section of the maze system and shrimp were held in the acclimation section for an additional 10 minutes. Each feed was tested separately and no mixing of water or shrimps between each treatment was allowed. After acclimation and addition of feed, the shutters were lifted, and shrimp were allowed to access the feed part of the maze (Fig. 4). The number of times shrimp interacted with the food was noted over 15 minutes.

Results

The average number of hits over the 15 minutes on diet 1 (15% fishmeal and 0% FeedKind) was 10.00 ± 2.87, while in diets 2, 3, 4 and the commercial diet, the number of hits were 15.30 ± 2.91, 18.33 ± 2.35, 16.60 ± 1.26 and 18.80 ± 2.82 respectively. The difference between the number of hits on the feed for the test diet containing no FeedKind was statistically significantly different from the commercial feed and those diets containing FeedKind. In addition, the attractability of feeds containing 10% FeedKind® was equivalent to the commercial diet, demonstrating that FeedKind® does not have an impact on the palatability or attractability of feeds to shrimp.

Conclusions

The study supports the previous work conducted by Calysta that replacing fishmeal as a protein source in shrimp feeds is feasible and that shrimp readily switch to eating diets containing FeedKind with no loss of appetite. The combination of a protein source with sustainable credentials, that is palatable and has demonstrable health and growth benefits, makes FeedKind® a suitable replacement for protein in aquaculture feeds and when production begins later this year can be considered mainstream rather than “alternative”.

References available on request.

More information: Dr. Matt Longshaw

Senior Scientist Calysta E: mlongshaw@calysta.com

Dr. Wutiporn Phromkunthong

Associate Professor Prince of Songkla University E: wutipornp@yahoo.com

Dr Nutt Nuntapong

Researcher Prince of Songkla University

Baranee Bamrung

Research Assistant Prince of Songkla University

Dr Jarin Sawanboonchun

Technical Director Calysta E: jarin@calysta.com