The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium


G. Wm. Kissil* and I. Lupatsch

Israel Oceanographic and Limnological Research Ltd., National Center for Mariculture, P.O. Box 1212, Eilat 88112, Israel


As part of a continuing study aimed at finding effective plant protein alternatives to fishmeal, soy protein concentrate, wheat gluten and corn gluten meal were evaluated in combination and as sole sources of dietary protein in diets for gilthead seabream. Both growth trials and digestibility determinations were employed to evaluate the effectiveness of these plant proteins. Digestibility trials indicated superior protein digestibility for soy protein concentrate (92%), wheat gluten (96%) and corn gluten meal (90%) in comparison to fishmeal (86%), while digestibility of energy varied with only wheat gluten (91%, as opposed to 75% for soy protein concentrate and 72% for corn gluten meal) being more available than fishmeal (84%). Diets used in growth trials were as isonitrogenous and isoenergetic as possible. The diets were supplemented with phosphorus and amino acids at levels determined in separate trials as being sufficient yet not growth-limiting.

Growth of seabream (40-130 g) on diets containing soy protein concentrate or corn gluten meal as the sole protein source were inferior to the fishmeal only diet while the wheat gluten diet proved superior. Diets containing a mixture of equal portions of the three plant proteins replacing 25-100% of the fishmeal out-performed the all fishmeal diet by 9-16% greater weight gain.

The feed conversion ratio was significantly superior to fishmeal in the all-wheat gluten diet and in the 50% and 75% mixture replacements. In these treatments, fish used 9-10% less feed for their weight gain. The use of soy protein concentrate or corn gluten meal as the sole protein source in diets for seabream is not recommended while their use in combination with wheat gluten can provide a partial or complete alternative to fishmeal. In a mixture, the wheat gluten is likely supplementing nutrients that may be limiting in the two other protein sources. The economic feasibility of using this mixture of plant proteins to replace fishmeal in seabream diets was evaluated, based on the costs of the feed ingredients in Israel.