32 JUNE 2017 • WORLD AQUACULTURE • WWW.WAS.ORG weeks of growth, 3) automatic feeder distributing feed six times per day using the same ration as the SFP, and 4) the AQ1 feeding system that fed ad libitum using a hydrophone and computer software to monitor feeding activity. The SFP was calculated based on an expected weight gain of 1.3 g/wk, a feed conversion of 1.2, and a survival of 75 percent during the culture period. Shrimp in the SFP and SFP+15 treatments were fed manually twice daily (0800 and 1600 h). Shrimp in the automatic feeder treatment received feed six times daily (0800, 1000, 1200, 1400, 1600, and 1800 h). The acoustic feedback can be used once shrimp are 3-4 g or when a sufficiently strong signal is received by the hydrophone. In our case, we initiated the system four weeks after stocking, when shrimp were 6 g. The computer system allows selection of maximum daily feed inputs and times. Based on our pond size, we limited the daily feed to 12 kg/pond (120 kg/ha) and fed only during daylight hours 0700 to 1900 h because the noise of aerators operating at night interfered with sensing of shrimp feeding by the hydrophone. Automatic feeder and AQ1 treatments were not randomly assigned to ponds because of constraints associated with the location of the power supply, although the SFP and SFP+15 treatments were randomly assigned to the remaining ponds. Juvenile white shrimp (initial weight of 0.07 g) were collected from a nursery system and stocked at 17/m2 in 16 production ponds at the Claude Peteet Mariculture Center, Gulf Shores, AL. Ponds used for grow-out were approximately 0.1 ha and shrimp were reared under standard conditions for 16 weeks (Sookying et al. 2011). Final production data averaged across the four treatments was a yield of 3504 kg/ha, individual weight of 28 g, an FCR of 1.03, and survival of 72.6 percent. A summary of the production data for the four treatments is displayed in Table 1. There were no significant differences in survival or FCR. However, yield, final mean weight and weekly growth of shrimp cultured using the AQ1 feeding system outperformed shrimp in the other feeding treatments. The final mean weight and weekly growth of shrimp in ponds with automatic feeders was also greater than those of shrimp in the two manually fed treatments. This indicates that simply increasing the number of feedings per day increases growth performance without increasing the daily amount of feed offered. The culture performance of shrimp in the SFP and SFP+15 treatments were not significantly different. Table 2 provides a summary of and economic analysis of trial results and shows a significant advantage of the AQ1 treatment for The AQ1 SF200 control box at the side of a shrimp research pond. Photo: Allen Davis. An automatic feeder connected to the AQ1 system in a 0.1-ha shrimp pond. Photo: Allen Davis. Cast net sampling is used to assess shrimp growth rates and conduct health checks. Photo: Carter Ullman. (CONTINUED ON PAGE 34)
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