EFFECT OF REPLACING FISH MEAL WITH MEAT AND BONE MEAL IN NILE TILAPIA (O. niloticus) DIETS. 1-NUTRITIONAL EVALUATION AND SAFETY ASSESSMENT STUDY

A growth trial was conducted firstly, to evaluate the effects of using meat and bone meal (MBM) instead of fish meal at rate of 0, 25, 50, 75 and 100% in diets on the growth performance and feed efficiency of Nile tilapia (Tilapia niloticous). Secondly, to assess the safety of inclusion MBM as animal protein source in fish feeds. Five iso-nitrogenous (32% crude protein) and iso-energetic (3500 Kcal estimated digestible energy) diets replacing 25, 50, 75 and 100% of fish meal by MBM were formulated. Each diet was randomly allocated to duplicate groups of fish in fiberglass tanks and each tank was stocked with 25 fingerlings (initial average body weight 1.80 ± 0.15g). Fish were hand fed the experimental diets four times per day for 60 days. For microbial safety assessment of examined fish, three samples from each group were collected at the end of the experiment in sterile bags to measure total bacterial count, total faecal coliform count, bacillus cereus, salmonella and staphylococca. There were no significant differences in terms of final body weight, average weight gain percentage and specific growth rate among fish fed the control diet and those fed diets contained meat and bone meal up to 50% replacement. There were also no significant differences in terms of feed intake, feed conversion ratio and protein efficiency ratio between fish fed the control diet and those contained 25% replacement of fish meal with meat and bone meal. The lowest performance had been recorded for the group of fish fed diet containing 100% meat and bone meal. Total Coliform Count, Faecal Coliform count, Bacillus cereus and Salmonella were not detected in all examined samples. The obtained results of Staphylococcal count showed no significant difference between all groups. The economical efficiency study demonstrated that replacing 25% of fish meal with meat and bone meal had the best net revenue 60.92 L.E. followed by the control 60.88L.E.  and 50% replacement  of fish meal 58.98 L.E.   
Although the present results showed that MBM could safely replace up to 50% of fish meal content in Nile tilapia diets without any adverse effect on Nile tilapia performance and its safety use. Yet, the 25% replacement was the most economical.