Abstract
The effect of substituting fishmeal with crustacean (Callianassa) meal in the diets of mixed sex Nile tilapia (Oreochromis niloticus) fry (0.2 g) was evaluated. Three isonitrogenous and isolipidic diets were formulated to contain 30% CP and 15% CL where fishmeal was substituted with Callianassa meal at 0, 25 and 50% in diets R1, R2 and R3 respectively. The experiment lasted for 6 weeks. The stocking density was 10 fish per tank in an isolated system and the capacity of each tank was 50L. Each treatment was administered in duplicates and fish were fed three times per day (09h, 13h, and 17h). The daily ration corresponds to 10% of the live weight of the fish during the first 2 weeks and was reduced to 8% and then 6% for the second and last two weeks of the trial period. At the end of the experiment, fish fed on R1 (control) diet and R2 diet (25% fishmeal replacement) had similar final weight (0.62 g), absolute mean weight gain (0.42 g), relative mean weight gain (210 %) and specific growth rate (2.50 %) and were significantly different from the values obtained from those fed on R3 diet (50% fishmeal replacement). R3 diet had the best FCR (1.42) and was significantly different from the values obtained from R1 and R2 diets but the values of the diets were not significantly different. The dry matter content of the initial fish (96.33%) and those of the R1 (94.12%) and R2 (95.71%) diets did not differ significantly but were slightly higher than that of the value obtained from fish fed on R3 diet (91.15). The protein content of the initial fish (49.63%) was significantly lower than the values obtained from fish fed on R3 diet (61.95%), R1 diet (54.74%) and R2 diet (52.59%). The fat content of the initial fish (41.51%) was higher than the values obtained when fish were fed on the experimental diets. Among the tested diets, the higher the crustacean meal in the diet, the lower the fat content of the fish muscle. The fat content of R1 (control) diet (29.56%) was slightly higher than the value of R3 diet (24.44%) and slightly lower than R2 diet (32.56%). It is concluded that crustacean meal can replace 25% of fishmeal in the diet of Nile tilapia (Oreochromis niloticus) fry at 0.2 g without any effect on the growth performances and feed efficiency.
Highlights
The strong demographic growth is increasing the demand for fishery products, a large part of which is provided by capture fisheries
At the end of the experiment, fish fed on R1 diet and R2 diet (25% fishmeal replacement) had similar final weight (0.62 g), absolute mean weight gain (0.42 g), relative mean weight gain (210 %) and specific growth rate (2.50 %) and were significantly different from the values obtained from those fed on R3 diet (50% fishmeal replacement)
The present study reveals the importance of crustacean meal as an essential ingredient in tilapia feed
Summary
The strong demographic growth is increasing the demand for fishery products, a large part of which is provided by capture fisheries. The productivity of this sector is declining because most of the fish stocks are either over-exploited or fully exploited and only a few stocks are under-exploited. Declining catches is characterizing the current situation of scarcity of fish in the world. Aquaculture is considered to be the sector capable of increasing fish production and animal protein intake for the ever-growing population. The world production of farmed fish for human consumption has been remarkably increasing and stood at 73.8 million tons in 2014 while in 1960, it was just 1.6 million tons (FAO, 2016). The pivotal role aquaculture is playing in supplying fish to the market during these decades has made it to be considered as one of the most highly productive animal producing activities. The 73.8 million tons produced by aquaculture in 2014 was estimated at US $ 160.2 billion at first sale which
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