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June 16, 2015

The World

Feeding Trays: Advantages and Disadvantages

 

Feeding trays are typically used to avoid overfeeding in aquaculture production systems.  They are sometimes used to deliver 100% of the feed and other times to evaluate broadcast feeding efficiency with a small number of trays.  They are credited with reducing feed cost per unit of production, but there is seldom mention of their effects on overall crop profitability.

 

 

Advantages of Feeding Trays

 

• Reduced feed-conversion ratios.

• Reduced feed costs.

• Improved growth, frequently.

• Improved water quality, which supports increased stocking density, greater yield and reduced environmental pollution.

• Assessment of size classes in the pond.

• Assessment of predators and competitors.

• Discovery of uninhabited areas of the ponds.

• Observation of the animals, which contributes to rapid management decisions concerning feed rates, health management and harvesting times.

• Discovery of even minor mortalities from dead animals carried to trays by shrimp searching for fresh feed.

• Cleaner pond bottoms.

 

 

Disadvantages of Feeding Trays

 

• Employees who perform feeding must be competent, properly trained and economically motivated.

• Using trays without proper supervision can cause huge problems.

• Trays should be on buoys, not tied to fixed posts that result in depressions in pond bottoms.  This requires two-person feeding teams and results in substantial cost increases.

• The number of daily feedings per day is limited because of the time required to apply the feed.

• Feed tray designs must be correct, but there is no industry standard.

• The amount of feed that can be placed on a tray at one time is limited.

• The decision to increase or decrease feeding rates is based on human interpretation.  It is not an exact science and is thus subject to considerable error.

• Trays and related gear require a lot of maintenance.

• Feed that leaves feeding trays by currents or poorly designed trays can lead to misinterpretation and overfeeding.

• Shrimp dive and dig for feed dropped near trays, which causes depressions that fill with uneaten feed and detritus that is repulsive to the shrimp.

• Feed removed from trays by shrimp that consume only a portion of it can lead to misinterpretation and overfeeding.

• At temperatures of 33° C and above, shrimp rapidly remove feed from trays, but do not grow faster, according to reports from Thailand.

• Feeding with feeding trays increases labor and other costs, requiring careful cost-benefit analysis.

• Very few articles in the literature provide detailed analyses of the effects of feeding trays on pond profitability.

• Studies report that using feeding trays improves growth rates, which is logically believed to be a result of improved water quality.  However, it is quite possible that growth rates may not be optimum because animals are not fed sufficient quantities of feed to maximize their genetic potential for growth.

• When broadcast feeding is based on a few sample feeding trays in the ponds, there is considerable opportunity to significantly underfeed or overfeed the shrimp.  This is especially true as stocking densities increase. 

 

Conclusions

 

A review of the limitations clearly shows numerous reasons why the use of feeding trays can result in incorrect conclusions concerning optimum feeding rates for maximized growth rate and survival.  The shrimp farming industry must continually challenge existing management protocols to see if assumptions remain accurate under current practices.  This article strongly suggests a serious review of the various techniques and assumptions associated with the use of feeding trays.

 

Source: The Global Aquaculture Advocate (The Global Magazine for Farmed Seafood).  Editor, Darryl Jory (dejry2525@aol.com).  Feed Trays–The Good, the Bad, the Ugly.  Thomas R. Zeigler (email tom.zeigler@zeiglerfeed.com) and Scott E. Horton (email guategringo@gmail.com).  Volume 18, Issue 3, Page 22, May/June 2015.

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