Nutrient sparing concepts in aquatic diets are recognized as reasonable approach to
support sustainable and efficient use of marine resources and thereby contribute against
overfishing. Simultaneously, the reduction in marine protein source (MPS) often causes
reduced health status and thus increased mortality of animals grown in aquaculture.
The objective of the current study was to investigate the impact of a phytogenic feed
additive (PFA) on shrimp performance in a nutrient sparing concept over a period of
57 days. A total of 240 white-leg shrimps Litopenaeus vannamei (1.5 – 2.0 g body weight (BW)) were randomly allocated to 12 tanks (RAS system with
appropriate water quality parameters) which were divided into two experimental groups
(n=6). Both groups received a diet based on soybean meal, wheat and corn, including
15% MPS. One group additionally received 0.2 g/kg feed of the PFA, an encapsulated
blend of essential oils with thymol as major component. Shrimp health was monitored
through observation and water quality parameters were recorded daily. BW as well as
feed consumption were determined at day 0, 28 and 57. Hepatopancreas weight was measured
at trial end. Statistical analysis comprised Student’s t-test and Kolmogorov-Smirnov
test. Over the entire trial period, the PFA group showed increased biomass (p<0.001)
and weight gain per tank (p<0.001), survival (p=0.004) and decreased feed conversion
ratio (FCR, p=0.001). Especially the improved FCR demonstrates how PFAs can promote
a better efficacy in nutrient utilization which ultimately yields an improved health
status, increased survival whilst contributing to improved sustainability through
reduced effluents.
