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Add To Calendar 28/04/2016 15:10:0028/04/2016 15:30:00America/ChicagoAsian-Pacific Aquaculture 2016FISH SIZE AFFECTS LYSINE UTILIZATION EFFICIENCY AT MARGINAL LYSINE INTAKE IN NILE TILAPIA (Oreochromis niloticus)   Diamond 1The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY


Erwin Suwendi*, Dominique P. Bureau, Cláudia Figueiredo-Silva, P. Hidayat, Katheline Hua
Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Faculty of Life Sciences, Humboldt Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany

Determining a reliable amount of digestible lysine (Lys) in feed formulation for different weight class of fish has always been a challenging task in aquaculture industry. Nonetheless, it remains questionable whether Lys utilization efficiency is similar across weight class of growing fish. In the present study, three wheat gluten-based diets were formulated to isoproteic (35.9% as is) and isoenergetic (19.5 kJ/g as is) and to contain graded levels of Lys: 0.9 (basal), 1.1 and 1.3% as is using Lys-HCl. Each diet was hand-fed to near-satiety to three groups of male Nile tilapia with different initial mean body weight (9.8 g, S; 58.1 g, M; and 247.6 g, L) over a 12-week period at 28⁰C in recirculated aquatic system. Lys utilization efficiency was assessed by comparative carcass analysis and analyzed through linear regression analysis.

The results showed that weight gain, thermal growth coefficient (TGC), feed efficiency (gain:feed) and protein, energy and Lys depositions increased significantly with increasing dietary Lys content or intake at each fish size. The efficiency of Lys utilization (slopes of the linear regressions) was estimated at 68%, 63% and 47% for S, M and L fish, respectively. Pooling together the estimated value of Lys utilization efficiency described a quadratic function with an equation: Lys utilization efficiency= -0.064 x (natural logarithm of body weight) + 0.85; R2= 0.88. The equation produced from the present study could be a valuable tool to predict Lys utilization efficiency from fingerling until market size for production and feeding management on commercial scale of tilapia culture operations.

Finally, Lys was indeed a limiting factor for nutrient deposition and increasing Lys level in isoproteic and isoenergetic diets led to dramatic increase of feed intake regardless of any weight classes of fish, at least at marginal Lys intake.

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