Setting up an efficient aquaculture feeding strategy

Feed is the largest expense in most fish farms, accounting for up to 80 % of the total costs involved in rearing cycles. Choices related to feed composition, modes of feeding, and modes of distribution are key to sustainable farming. What are the factors to consider when developing a feeding strategy?

Whatever the fish farming system, feed is almost always its main budget item. This also applies to semi-intensive farming systems where pools and ponds naturally produce nutrients. Investments in phytoplankton growth and maintenance are also attributable to feed expenditures.
It is therefore of the utmost importance to design a feeding strategy that allows for optimised animal performance and minimal waste. An effective strategy is one that provides each animal with a feed whose content and digestibility are sufficient for its needs (maintenance and growth).
Out of the 150 to 200 aquatic species of fish that are currently being farmed, only a dozen have been the subject of significant research. Research has allowed for an empirical estimate of these animals’ nutritional needs, and the feed industry has made significant progress in manufacturing feeds that are better suited to the diverse species being farmed and the various farming conditions.

• The number of animals in the pool: this often overlooked variable is at the core of an appropriate feeding strategy.
• Water temperature: the closer the water temperature is to the thermal optimum of a given species, the more substantial the portion should be (see graphic).
• Health conditions: a healthy population of animals will usually have more appetite than a group of sick animals.
• Feed composition: depending on the chosen feeding strategy, the feed content is more or less rich in nutrients.
• The stress state: a fish will react more intensely to stress when it is in the process of digesting. Feeding intakes should therefore be reduced to a minimum around the time of a stressful event. 
• The amount of oxygen available: feed ingestion can trigger increased metabolic activity, increasing the animal’s need for oxygen.
• Split-meal delivery:  this is an essential variable in determining the amounts of feed that are to be distributed.
• The spreading of the feed: the spatial pattern of feed delivery is also an important factor to consider. It is necessary to ensure that the feed distributed over the tank or cage surface is spread as evenly as possible, especially if animal density is very high. Automated distribution systems allow for an optimal distribution of feed.
• Consideration of excretions: the need to limit pollution from excretions varies depending on environmental and legislative constraints. The amount of feed distributed directly influences the pollution produced (solids, dissolved). A well-thought rationing strategy should limit this pollution.
• The evaluation of feed ingestion: it is always necessary to check that the feed distributed is well ingested by the animal. Many tools, such as underwater camera devices enclosed in sea cages or feeding platforms over the ponds, can provide a good indication of the amount of feed ingested. In the case of tanks and aquariums the amount of pellets recuperated at the exit of pools can give a good hint of what has actually been ingested or not.

Would you like to devise an effective feeding strategy tailored to your farming needs or those of your customers? Techna supports feed manufacturers and farmers throughout this process. We can help you optimise the composition, texture, and distribution of feed, and most efficiently observe your animals’ behaviour so that you can best meet their needs. Please contact our experts!