EVALUATION OF DATES AND DATE PITS AS DIETARY INGREDIENTS IN TILAPIA (OREOCHROMIS-AUREUS) DIETS DIFFERING IN PROTEIN-SOURCES

Seven isonitrogenous (40% crude protein) and isocaloric (18.6 kJ/g gro ss energy) diets were formulated to investigate the utilisation of dat es and date pits as carbohydrate sources for tilapia fry (Oreochromis aureus) and to evaluate the complete substitution of fish meal by poul try byproduct and blood meals. The growth and feed utilisation efficie ncy of fish fed on diets in which poultry byproduct meal was the only animal protein source were higher (P<0.05) than with the other two pro tein sources. Since these results disagree with those of previous stud ies with other fish species, it was assumed that the low performances of fish on fish-meal and blood-meal diets were due to inadequate proce ssing of the raw products. The inclusion of the dates and date pits di d not influence the growth of the fish. A trend of increasing body-pro tein content and decreasing fat was observed in fish fed diets supplem ented with date-pits meal. An estrogenic action of date pits was hypot hesised as the direct cause of this phenomenon. Copyright (C) 1996 Els evier Science Ltd.