Theses and Dissertations


Title: OPTIMIZATION OF DIETARY NUTRIENT INPUTS FOR PACIFIC WHITE SHRIMP Litopenaeus vannamei

Name: Venero, Jesus A.

Degree: PhD

Chair: D. Allen Davis

Resides: FAA library

University: Auburn University

Location: Auburn, Alabama

Date: 2006

Pages: 161

Keywords: marine shrimp, Litopenaeus, diet, protein, energy

Abstract:

A series of studies were conducted with Paciiic white shrimp, Litopenaeus vannmnei, with the objective of optimizing feed input and improving feeding management strategies to reduce wastes and the potential of negative environmental impacts of shrimp aquaculture. In the first study, two trials were conducted with juvenile (2.2 g +- 0.2, n = 30) and sub-adult (1 1.1 +- 0.4, n = 30) shrimp. Digestible protein (DP) and digestible energy (DE) requirements for maintenance of shrimp were determined using a factorial procedure. The DE requirement for juvenile shrimp was 41.1 Kcal/kg BWd (body weight per day) and the DP requirement was 2.82 g/kg BWd. For juvenile shrimp, the efficiencies of DE and DP utilization were 0.29 and 0.54, respectively. The DE requirement for sub-adult shrimp was 50.3 Kcallkg BWd and the DP requirement was 3.6 g DP/kg BWd. The efficiencies of DE and DP utilization and were 0.42 and 0.72, respectively. Data on DE and DP requirements as well as the partial efficiencies of utilization and deposition of dietary DE and DP were used to formulate a bioenergetics model to calculate daily feed allowance for shrimp cuiture. Values of feed allowance determined using the bioenergetics model showed that shrimp could be fed with diets with different levels of DE and DP, but the levels of feed input had to be adjusted to the energy and nutrient density of the diets as well as the growth rate of shrimp under the specific biotic and abiotic conditions. In order to verify this statement in practical conditions, the growth response of juvenile shrimp to a 30 and a 40% CP diet offered at the same input of nitrogen was evaluated in tank and pond trials. In a tank trial, both the 30 and the 40% CP diets were offered at three feeding rates (100, 75, and 50% standard feeding). At the conclusion of the trial (56 days) there were no significant differences in final weight between shrimp offered the 30% CP diet fed at 100% of the ration and the 40% CP diet offered at 75% of the ration (10.3 g, mean weight), which provided the same protein input. These results demonstrated that under controlled experimental conditions, shrimp can be fed with diets containing different levels of nutrients or energy,
but the levels of feeding have to be adjusted to the energy and nutrient density of the diets. In the pond trial the same two diets (30% and 40% CP) were offered to juvenile shrimp (0.04 +- 0.04 g, n=56) at two feeding rates (100 and 75%). At the conclusion of the trial (114-121 days), there were no significant differences in final weight among shrimp from the different feeding treatments (19.7-21.7 g). However, production was signifcantly higher for the treatment 30-100% than for the treatment 30-75% (6,482 versus 5,054 kg/ha). Yield for the 40-75 treatment tended to be lower than that of the 30% CP diet offered at standard rate (30-100%). However, this statement was not evaluated statistically due to loss of two ponds of the 40 -75% treatment. In order to evaluate the effect of the DE/CP ratio under these isonitrogenous feeding regime, a third study was performed with juvenile shrimp in a clear water recirculating system. Two treatments consisted of 30% and 40% CP diets (30 ISO-100% and 40 ISO-75%, respectively) with a constant level of DE (3.28 Kcal/g). Two treatments consisted of 30% and 40% CP diets with variable levels of DE (2.70 Kcal/g and 3.6 Kcal/g, respectively) to maintain a constant DE/CP ratio of 9 Kcal/g of protein (30 RAT-100% and 40 RAT-75%, respectively). At the conclusion of the trial (49 days) there were no significant differences among the four feeding treatments, which indicated appropriate levels of energy inputs for all the treatments. However, the feed conversion rate (FCR) was lower for the low feeding rate treatments (75% feed rate) (1.48 and 1.50 versus 2.09 and 2.06). Results obtained in this study with the development and experimental application of a bioenergetics model support the principle that shrimp feed input should be based not on constant nutrient requirements referred as a dietary level of the nutrient, as traditionally has been used, but as a daily quantitative requirement that can be supplied with diets with variable levels of nutrient and energy.

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