Shrimp Culture
Biofloc flask Paddle wheels in a grow-out greenhouse
production of shrimp with no water exchange from stocking through to harvesting. INVE is supporting Viet-UC with continuous on-site assistance by a technical support team that includes shrimp culture experts with an accumulated experience of more than 185 years. It has today a complete portfolio of products specifically developed to support shrimp grow-out production.
Approach and general setup Since mid-2015, the team has completed several commercialscale production runs. These were designed to introduce the high density zero water exchange protocols, together with the use of the grow-out product portfolio. The know-how transfer introduced by the INVE team met Viet-UC’s production requirements and performed well under local conditions, resulting in a simple, easily replicable production system, which is indispensable for the multiple expansions planned by the company’s grow-out program. As of today, a total of five full-scale production cycles have been conducted over a total of 100 production ponds. The first couple of trials were designed to secure the farming targets using zero water exchange protocols, first experimentally and then commercially. Following these successes, several runs to increase farming outputs with higher stocking densities were conducted. This article summarises the output, explaining the approach and its results. All of the grow-out production were carried out in 500 m2 fully lined ponds, which are 1.2 m deep. The aeration system comprised 2.5 cm (1”) aero-tube diffusers and air was supplied by root blowers. Two long-arm paddle wheels were installed to use as back-up in case of failure of any air blower. The water used was previously disinfected and treated to ensure the removal of pathogens. All ponds were stocked with the selected genetic lines of post larvae (PL 10) supplied by inhouse hatcheries. High quality shrimp feed (40% crude protein) was used. Feed was distributed manually up to 1 g size crumbles; then pellets were distributed via the use of automatic spinner feeders positioned in the centre of the ponds over a 24-hour period. The main principle of the zero water exchange protocol is based on bacterial competitive exclusion, via the use of the selected probiotic bacteria. Also, it should be noted that shade cloth was installed over the ponds to minimise competition and deviation of the physico-chemical parameters due to the phytoplankton population.
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July/August 2017 AQUA Culture Asia Pacific Magazine
Trials baseline protocol Prior to stocking, all the materials and pond surfaces were disinfected with a solution of Sanocare®PUR, to ensure the complete removal of possible pathogens, including bacterial biofilms. After the first pond was filled, no water was added or exchanged into the tanks for the entire period of the crop. During production, two products were used as inoculum of beneficially selected bacteria, or probiotics: the Sanolife®PRO-W for water conditioning, and Sanolife®PRO-2, used as feed coating to act at the level of the shrimp gut bacterial ecology. Both products include a combination of bacteria, with multiple targets: • Bacterial competitive exclusion for space against Vibrio sp. in the water and biofilm colonisation of pond surfaces and gut internal membranes, • Bacterial competitive exclusion for food source of Vibrio sp. via the reduction of organic waste production, • Bacterial competitive exclusion for food source of Vibrio sp. via an improved control of multitrophic nitrification bio-reactions The optimisation and control of the multitrophic nitrification processes remain until today the major limitation to the development of zero water exchange protocols around the globe. Indeed, production systems of this kind, commonly referred to as biofloc production systems, use mainly the heterotrophic nitrification bacterial processes, working with a carbon:nitrogen (C:N) ratio via the addition of external carbon sources, such as molasses, to the ponds. This nitrification pathway alone is not sufficient to digest all the nitrogen involved in a shrimp pond with zero water exchange. Ammonia spikes, followed by nitrite spikes often impact the overall productivity of such systems. In addition, within the specific protocol, special focus is brought to the first month of farming, when the pond ecology is developing. During this time, a high quality nursery feed supplement (Sano®SPAK) is used for the first feeding of each day. S-PAK also includes a complete range of selected immunostimulants to stimulate the shrimp defense against environmental stress (such as high density stocking). Subsequently, the immunostimulants present in the nursery feed supplement are given to the post larvae in the form of the supplement Sano®TOP S, which is coated onto the feed.