Benefits of autofeeder in aquaculture
2019-06-18 Admin Ann
Blue Aqua International
The Practical Vol.4 issue13
The use of automatic feeding technology has been widely spread in the last decade in South East Asian countries. In Thailand, there is autofeeder developed in the country where shrimp is intensively produced.
Feed cost accounts more than half of total expenses in shrimp farming. Therefore, benefits of using automatic feeder, apart from the feed expenses savings, are visible when compared to manual feeding. Manual feeding is the traditional method, which requires constant hand labor for multiple feeding applications. These feed generally are not fully consumed, results in deteriorating water and soil quality.
In the case of automatic feeders, feed is applied in small but frequent doses, covering a circular area depend on the spreading characteristics and its position in the pond. This frequent feeding strategy allows shrimp to catch the pellets before it reaches the pond bottom thus water quality deterioration is lower. Shrimp in all sizes are evenly fed.
More efficient feeding management through feeding amount, effective feed distribution, and interval between broadcast adjustments enables a continuous shrimp feeding behavior. Besides preventing feed waste accumulation at the pond bottom, feeding management also assures lower FCR and improves shrimp growth. This latter is directly observed in larger average daily growth rates and shorter production cycles. A more frequent feeding enables a constant growth of all stocked shrimp, observed with lower broken size at harvest.
Unlike manual feeding, automatic feeding reduces the fluctuation of the most important water quality parameters such as dissolved oxygen, ammonia and nitrites. Therefore, downward or upward peaks are not observed or significantly diminished. Anaerobic areas due to feed accumulation and nutrient leaching of leftover feed are minimized as well.
In overall, installing an automatic feeder ensures a healthier shrimp due to improved water quality and continuous feeding. Improving water quality reduces the risks of mortalities or disease outbreak, thus fetching larger profits with additional savings on labor and production costs.
Placing the automatic feeder at the pond
The Automatic feeder set up along the pond can be approached in several ways. One of the most common ways to have the feeder running is by placing it on the top of homemade raft or buoyant platform. Many farmers leave autofeeder floating by means of empty barrels or drums tied up together, or using the floating parts out of some dismantled paddlewheels. The floating platform is repeatedly fetched back and forth along one section of the pond through a rope system placed on one or two sites of the embankment. Obviously this method is not very convenient if the autofeeder is intended to operate on a very often basis (as we recommended).
Alternatively, the autofeeder can be set up at the end of the feeding catwalk keeping in mind, however, that the end of the catwalk must be extended further than the maximum autofeeder-operating radius. For instance, if the maximum broadcasting radius for a given autofeeder is 12 meters, the feeding catwalk must be at least 12.5 meters long in order to ensure that the pellet rain falls within the pond surface.
The height of the feed dispenser above the water constitutes also a relevant factor to keep in mind. In this regard, if the dispenser is located too distant over the water surface, operators can have problems to reach the lid of the tank and then refill the autofeeder. Conversely, if the feed dispenser spin is set too close to the water surface, the broadcasting range is shortened in a way that renders useless the function of the feeding trays. The latter situation would lead to having a pellet “dumping spot” in front of the feeding catwalk negatively affect both water quality and the shrimp size variation.
Aside from the pellet broadcasting range and whether or not it interferences the pond borders, the paddle wheels aerators should be prevented from being located directly in middle of the pellet falling trajectory. It is recommended to position it at least of 1.5 meters away from aerators in order to avoid strong water currents that may difficult shrimp feeding.
Considering that a single autofeeder can feed a population of 500,000 to 700,000 shrimp, only one autofeeder will be necessary for small pond while larger ponds will require multiple autofeeders. The latter case must avoid overlapping their broadcasting area. In case of very long and narrow ponds, autofeeders will be placed on the opposite end of each other.
The feeder is placed at least 50 centimeters above the water surface to cover the required area. Not only its position above the water, but also the power of the spreading motor and the type of the feed and its size are relevant. The larger the feed pellets is, the larger area it will cover. Feeder placement should encompass all the factors mentioned above and the aquaculturists must take them into account as per feed type, size or even selected commercial brand.
Shifting from manual to automatic feeding
At initial stage of production, blind feeding is practiced as usual while automatic feeder can be operated from the second week onwards according to the farmer judgment. Generally, any day between 15 to 25 days after stocking is possible.
As mentioned above, feed type, powdered and pelleted, and its size have to be adjusted for a better feeding accuracy, whenever those functions are available in the control panel.
Microcomputer system control panel
Feeders are controlled by an electronic unit which hosts a microcomputer, located in a panel control, and integrates all feed-related information, such as type, amount, time and interval between rations.
Duration of the feed dispersal is automatically determined by the microcomputer system from the total feed quantity and operating hours. Approximately during the first month, feed is distributed more frequently but in smaller rations due to shrimp feeding habits. Afterwards, an increasingly larger quantity lapsed with a larger gap is distributed.
As a matter of fact, most of the feeders can operate 24 hours a day. Nonetheless, it is a common practice to use them 10 to 14 hours a day to avoid night dissolved oxygen drops and to allow shrimp feeding on natural food during the nighttime.
Being an electronic device, care must be taken to protect the panel against the humidity and the rain. Hence, the control panel must be installed inside a watertight cabinet when the autofeeder is operated outdoors by the pond or at the end of the feeding bridge.
One desirable feature of the autofeeder drum is that it requires the minimum maintenance/manipulation possible over the day-to-day pond operations. Precisely, among the improved characteristics of the autofeeders, a big capacity drum or deposit is preferred. In addition to this, the selection of rugged materials for the autofeeder design is of the upmost importance provided that those materials don’t alter the quality of the stored feed over the time. It is also advisable to check the degree of moisture concerning certain pelleted diets prior to refill the autofeeder drum for the same reasons that we have just pointed out.
Feeding efficiency monitoring and regulation
Monitoring shrimp feeding is carried with feeding trays as in the traditional way. It is advisable to set two feeding trays per each autofeeder, placed about 15 centimeters above the pond bottom, covering the broadcasted area, one close to the feeder and another one at 6 to 8 meter approximately from the feeder.
Feed ration, time and frequency are adjusted by using feeding trays observations as an indicator. Generally, feed ration is up or down adjusted by 2-3% depending on shrimp feeding, or feeding frequency modified. Theoretical shrimp weight and survival estimations are used as additional information for a more realistic feeding adjustment.
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• Set frequency and quantity of feed by digital control.
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• Over 98% accuracy of feeding control, including adjustment of accuracy control for powdered or pelleted feed.
• 8-14 meters radius distribution range, widely and equally distributed.
• Savings on electric bills, uses only 50 watt.
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