Nutrient mass balances in semi-intensive shrimp ponds from Sonora, Mexico using two feeding strategies:: Trays and mechanical dispersal

An experiment was conducted to determine the effect of two feeding practices - use of feeding trays (FT) and a mechanical feed dispersal device (FD) - on the growth performance and nutrient mass balances of white shrimp Litopenaeus vannamei. Cultured shrimp fed by feeding trays showed greater mean weight (32.3 +/- 0.9 g) and yield than those fed by mechanical dispersal (29.5 +/- 0.5 g). Feed added, shrimp survival and feed conversion were not significantly different between the two feeding strategies. Of the total input of nitrogen and phosphorus to the ponds fed by dispersion, 27.2% and 13.6% were recovered, respectively, yielding 2920 +/- 30 kg/ha of shrimp. Ponds in which trays were used showed nitrogen and phosphorus recovery of 28.3% and 14.3%, respectively, and a yield of 3325 +/- 153 kg/ha. The estimated environmental losses of nitrogen and phosphorus per ton of shrimp produced were 73.3 and 13.2 kg/ton, respectively, for the FD treatment; whereas in FT ponds losses were 70.6 and 12.8 kg/ton, respectively. This study showed the potential of feeding trays as a better strategy for shrimp culture that permits the addition of most feed rates by an improvement in yield of L. vannamei and a reduction of environmental losses of nitrogen and phosphorus in comparison to mechanical feed dispersion. (c) 2006 Elsevier B.V. All rights reserved.