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Simulation of nitrogen dynamics and shrimp growth in an intensive shrimp culture system: effects of feed and feeding parameters

Authors
Journal
Ecological Modelling
0304-3800
Publisher
Elsevier
Publication Date
Volume
122
Identifiers
DOI: 10.1016/s0304-3800(99)00123-4
Keywords
  • Litopenaeus Vannamei
  • Modeling
  • Nitrogen Dynamics
  • Shrimp Cultures
  • Simulation
Disciplines
  • Biology
  • Ecology
  • Geography
  • Medicine

Abstract

Abstract Worldwide increases in shrimp culture have caused concern about potential environmental impacts, particularly water pollution resulting from discharge of nitrogenous wastes from shrimp farms. This study describes development of a simulation model representing the effect of feed nutritional quality, feed physical characteristics, and feeding strategies on nitrogen dynamics and growth of the Pacific white shrimp, Litopenaeus vannamei, in intensive systems receiving dry feeds in the absence of natural productivity except bacteria. The model represents the addition of nitrogen to the culture system as dry feed, its consumption and metabolism by shrimp, and its loss in uneaten feed, particulate feed, feces, and excretion as ammonia. Shrimp somatic growth is based on the amount of nitrogen incorporated into whole body. The model was quantified using unpublished research results conducted at the Shrimp Mariculture Research Laboratory of Texas A&M University and published information on the species. The model is multivariate, deterministic, and uses a compartment model structure based on difference equations. Evaluation of the model consisted of simulating six indoor and one outdoor experiments that examined the effect of various feed and feeding parameters on shrimp growth. Simulated shrimp growth dynamics generally agreed with indoor experimental results but at low dietary protein levels (below 11%) and low feeding frequencies (below 2 times per day) simulated final biomass was underestimated by 22 and 50%, respectively. Simulated final biomass was overestimated by 15% when compared to the outdoor experiment. Simulations investigating a range of possible consumption rates suggested that either experimental animals used other sources of food or consumption rates for 2 g animals are underestimated in the literature.

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