EVALUATION OF SOME PLANT INGREDIENTS AS DIETARY-PROTEIN SOURCES FOR COMMON CARP (CYPRINUS-CARPIO L) FRY

A laboratory growth trial was conducted to evaluate the suitability of various oilseed cakes and leucaena leaf meal as dietary protein sourc es for common carp fry (mean +/- SE weight, 50 +/- 1.6 mg). Eleven exp erimental diets were formulated containing different levels of mustard , sesame, linseed, copra and groundnut oil cakes and leucaena leaf mea l to substitute for fish meal protein up to a maximum of 75% of the to tal protein content. Sesame oil cake was tested at three inclusion lev els (25, 50 and 75% of total protein), whereas mustard (25 and 50%), l inseed (25 and 50%) and groundnut (25 and 75%) oil cakes were each tes ted at two levels. Copra and leucaena were tested at one inclusion lev el (25% of total protein) only. The control diet was prepared with fis h meal as the sole source of protein. All diets were isonitrogenous an d contained about 40% protein. The experiment was conducted in a labor atory recirculation system with three replications for each treatment. The performances of the diets were evaluated on the basis of feed acc eptability, survival, growth, feed conversion, protein utilisation, pr otein digestibility, body composition and histopathological changes. T he results of the study showed that growth and performance were signif icantly affected by the type of plant protein as well as level of incl usion. There was no significant (P > 0.05) variation in the observed g rowth responses and feed conversion ratios among the control diet and the diets containing 25% linseed and 25% groundnut oil cakes. The diet containing 25% leucaena meal showed the poorest performance. Similar trends were also observed for protein efficiency ratio and apparent ne t protein utilisation, Apparent protein digestibilities were broadly s imilar (78-90%) for all diets except the diet containing 25% leucaena meal which showed the poorest value (63%). With the exception of the c ontrol and 25% leucaena diets, the carcass composition of experimental fish was relatively unaffected by different dietary treatments. Histo pathological examination of liver revealed higher levels of intracellu lar lipid deposition in fish fed diet containing mustard fake. A large proportion of fish fed the 75% groundnut diet showed severe deformati ons of the body. Based on these results, the possibility of using plan t ingredients as a partial replacement for fish meal in diets for the common carp fry is discussed. (C) 1997 Elsevier Science B.V.