Evaluation Of Dry Clover Meal As A Feed Protein Resource In Practical Diets Of Juvenile Grass Carp, Ctenopharyngodon Idella

In order to attain a more economically sustainable, environmentally friendly and viable production, the research interest has been directed towards the evaluation and use of unconventional protein sources. This study was conducted to evaluate the suitability of dried clover(Medicago sativa L.)meal as an alternative protein source for grass carp, Ctenopharyngodon idella. A56d feeding trial was carried out on6triplicate groups of20fish (8.72±0.34) g in250-L aquaria connected to a re-circulating system. Five test diets were formulated to contain clover meal at levels of2.5%,5%,10%,15%and20%of the diets or1.75%,3.5%,7.0%,10.5%and14.0%of the total plant dietary protein (Diet1,2,3,4and5) respectively and one diet acting as a control which included soybean meal, peanut meal, cottonseed meal and rapeseed meal as protein sources. All diets were isonitrogenous (28.5%crude protein) and isoenergetic (15.92MJ/kg). No mortality was observed during the whole test period. Fish in diets with2.5%and5%dry clover meal (Dietl and2) raised somewhat growth performance and feed effectiveness compared to fish in control. There was no significant difference of growth performance and feed effectiveness between fish in diet of10%dry clover meal (Diet3) and fish in control, but fish in diets with15%and20%dry clover meal (Diet4and5) significantly depressed growth performance and feed effectiveness compared to control (P<0.05). The depression of growth performance and growth parameters could likely be attributed to several factors. Saponins which found in many of the potential alternative plant-derived feed sources as antinutrients were considered to have a detrimental effect on the fish. A further possible reason for low growth at high dry clover meal inclusion levels might be the increasing of cellulose in diet. Dietary fibre apparently influenced the movement of nutrients along with the gastrointestinal tract and significantly affects nutrient absorption. Fibre could bind nutrients like fat, protein and minerals, and reduced their bioavailability. These results suggested that dry clover meal could be used to7,8%to adaptable diets and it substituted up to10%of dietary protein in grass carp without significant reduction in growth.