An Evaluation of Feed Management, the Use of Automatic Feeders, and Feed Leaching in the Culture of Pacific White Shrimp Litopenaeus vannamei
Type of DegreeMaster's Thesis
Fisheries and Allied Aquacultures
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Feed management is widely considered to be one of the most important factors of shrimp production, however it has been grossly under studied using standardized methods. New and improving technology is making the use of automatic feeders more realistic for many farmers and could reduce the feeding labor required for production. The objectives of the pond studies were to examine the impact of: 1) Number of daily feedings 2) daily feeding rate and 3) the use of acoustic feedback; on the growth and production performance of Pacific white shrimp Litopenaeus vannamei grown in ponds. Another related aspect of this works was the examination of the leaching of commercial feeds to help understand the mechanism of the benefit of increased daily feedings. One theory suggested by the pond trials was that the increased growth could be attributed to the shorter amount of time that the feed is in the water before being consumed. Shortening this time would result in less nutrients leaching from the feed. Hence, a tank based trial was conducted to evaluate the impact of leaching on the available nutrients in a feed and the growth of shrimp fed the leached feed. All experiments were conducted at the Alabama Department of Natural Resources in Claude Peteet Mariculture Center, Gulf Shores, AL, USA. The two pond trials were performed in 16, 0.1 ha ponds that were stocked at 17 shrimp/m2 (trial 1) and 38 shrimp/m2 (trial 2). Both trials examined the use of a standard feeding protocol (SFP)(1.3 g/wk, 1.2 FCR, and 1.5% weekly mortality), solar timer feeders, and AQ1 Systems acoustic feedback system. The feed leaching trial was performed in 24, round 800L tanks with a daily 5% water exchange from a shrimp production pond. Findings iii of the pond trials showed that increasing the number of daily feedings from 2 to 6 resulted in improved growth and increased shrimp values. Increasing the daily feedings also allowed for a higher daily ration without significantly impacting the FCR. The AQ1 treatment also produced larger shrimp than the timer or SFP treatments in both trials. The larger shrimp resulted in a higher total yield and a higher shrimp value. An economic analysis performed on trial 1 demonstrated that the increased shrimp value of both the timer and AQ1 treatments can offset the costs of implementation in as little as one production cycle. The leaching trial confirmed a decreased biological value of leached feed as the long the feed was pre-leached the poorer the growth rate of the shrimp. These results confirm that the use of automated feeding systems reduced the time feed was in the water prior to consumption and increased the availability of feed over time. Both factors result in improved growth rates of the shrimp resulting in significant improvements in total biomass production under the same time period. These results, also confirm the efficacy of automatic feedback systems for the use in growout ponds.