Response of Genetically Improved Heterobranchus Longifilis Juveniles to Different Diets Containing Beniseed Meal and Extruded Soybean Meal

Three isoproteic 35% crude protein diets were formulated with same basal ingredients and ranging levels of extruded soybean, beniseed and yellow maize meals and fed at 5% body weight to groups of genetically improved Heterobranchus longifilis juveniles of mean weight 79.57± 0.365g in nine out door concrete tanks each measuring 2x2x1m. The tanks were filled to 2/3 of their holding capacity with water fertilized with poultry manure 2 weeks prior to the commencement of the experiment. Growth and nutrient utilization indices; %Weight Gain (WG), Specific Growth Rate (SGR), Feed Conversion Ratio (FCR) and Protein Efficiency Ratio (PER), and water quality parameters; pH, Dissolved oxygen and Temperature were monitored for 56 days. The best growth and nutrient utilization values were observed in beniseed based diet with a significantly high values (P<0.05) for WG, SGR FCR, and PER. The high methionine content of beniseed meal coupled with the abundant lipids having a good array of polyunsaturated fatty acids were suggested as possible reasons for the better growth performance of the beniseed based diet. @JASEM Fish feed account for about 70% of aquaculture operation (FAO, 1983) and most fish farmers in Nigeria do not make use of standard fish feeds due to high cost (Eyo, 1995). Fish feeds were developed on the concept of `fish eat fish’, which is why fishmeal is often a traditional component of fish feeds. However, in recent times, the cost of fishmeal has made scientists to suggest the possibility of replacing plant protein feedstuff in fish feed production to reduce cost of producing the feed and the cost per kilogramme of produced fish weight (Falaye, 1992). Among the potential plant protein feedstuffs are soybeans and beniseed with crude protein ranging from 24 48 percent, crude lipids 15.0 50 percent, and very high nitrogen free extract (NFE) (Shiau et al., 1990, Aduku and Olukosi, 1991). Both are abundantly produced in Nigeria especially in the guinea savannah region of Benue and Oyo States. Catfish is highly relished in Nigeria because of its fast growth and the high taste value of the fish (Oladosu et al., 1994). The wild and the local fingerlings do not grow as fast as those that have been improved genetically through manipulations and this is a major constraint to rapid development of aquaculture industry and stock management in Nigeria (Aluko, 1994). The aim of the study is to determine the response of genetically improved Heterobranchus longifilis juveniles to diets containing beniseed and extruded soybean meals. In order to achieve this, the proximate composition of beniseed was determined as well as valuation of the growth performance and nutrient utilization of the genetically improved catfish on diets formulated with both plant protein sources. MATERIALS AND METHOD Feedstuffs used in the study were yellow maize grains, extruded soybean meal, groundnut cake, fish meal (clupeid), beniseed, blood meal, cod liver oil, bone meal and vitamin and mineral premixes. The genetically improved Heterobranchus longifilis juveniles were obtained from the NIFFR genetic laboratory. The clupeid fish were sun dried and milled to fine particles. Soybean seed was extruded at temperatures ranging from 135-140C and 30-40 bar pressure (Eyo et al, in press). The beniseed was toasted in an electric oven at 100C for one hour in the laboratory to destroy antinutritional factor especially Trypsin inhibitor, which is destroyed by heat treatment (Eyo 2001). The blood meal was prepared by first cooking the scarlet bovine blood in an aluminum pot to extract the serum and the black semisolid left over was sun dried and incorporated in the feed as blood meal. All ingredients except the cod liver oil, common salt, vitamin and mineral premix were milled together with hammer milling machine to obtain fine particulates, which was incorporated in the diets at various levels of inclusion as shown in Table 1. The crude protein content of the diets were kept essentially at the 35% level since this was determined as the protein requirement of juveniles catfish hybrid in a previous experiment (Eyo and Falayi, 1999) Each diet was first mixed dry and later with just enough warm water to obtain homogenous hard-paste JASEM ISSN 1119-8362 All rights reserved J. Appl. Sci. Environ. Mgt. 2004 Vol. 8(2) 29 33 Full-text Available Online at http:// www.bioline.org.br/ja *Corresponding author mixture (dough) in a pelletizer and rolled out into flat tray through 2mm die disc holes in different lengths. The pellets were dried in electric oven at 105C for 2 hours. 100g samples of each diet was put in sealed sampling bottles and sent to the laboratory for proximate analysis and the bulk was put in sealed polythene bags for feeding trial. Ninety juveniles of genetically improved Heterobranchus longifilis with mean weight 79. 57± 0.365g were acclimatized for 48 hours and arranged in groups of 10 homogenous fish. Each juveniles group was stocked in triplicate in nine concrete tanks each measuring 2x2x1m located outdoors. The fish were stocked in water fertilized with poultry manure 2 weeks before the commencement of the experiment. The fish were starved for 48 hours to empty their gastro-intestinal tract before the feeding trial. Fish were fed at 5% body weight daily (2.5% in the morning (7-8am) and 2.5% in the evening 5-6 pm, local time) throughout the duration of the experiment. Fish sampling: Fish sampling were done biweekly. Beach seine net was used to trap the fish and weighing was conducted with sensitive top loading balance. Physico-chemical parameters: Water samples were collected weekly for analysis of Temperature, Dissolved Oxygen (D0), pH and conductivity parameters using the APHA (1990) methods. Table 1: Composition of experimental diets and the proximate analysis.