ABSTRACT
A 90-day experiment was conducted with four-month-old juvenile tench to test seven diets differing in replacement level of fishmeal (FM) by soy protein concentrate (SPC): 0% (control diet), 45%, 55%, 65%, 75%, 85% or 100% corresponding to 0, 312, 383, 451.6, 521.7, 590 or 695 g SPC kg−1 diet, respectively. Methionine and arginine supplementation was included from substitution levels of 55% and above to reach similar values to those provided by the control diet. Survival rate was close to 100%. The highest total length (TL) and weight (W) were reached with the control diet without significant differences from 45% to 55% diets. Significant lower TL, specific growth rate and daily increment in total length were obtained with 65% or higher replacement levels. The percentages of fish with externally visible deformities ranged from 0% to 9.3%, being higher with 75%, 85% and 100% replacement diets.
Abbreviations
TL: total length
W: weight
SPC: soy protein concentrate
FM: fish meal
ANF’s: antinutritional factors
EAA: essential amino acids
NEAA: non-essential amino acids
SGR: specific growth rate
ITL: daily increase in total length
K: condition factor
Acknowledgments
We thank the collaboration of Cargill España (Madrid) and Skretting España S.A. (Burgos) for providing us most of the ingredients of diets.
Disclosure statement
No potential conflict of interest was reported by the author(s).