Effect of dietary protein level and commercial feeds on growth and feeding of juvenile common snook, Centropomus undecimalis (Bloch, 1792)

Preliminary results of the effects of different dietary protein levels and commercial feeds on growth and feeding of juvenile common snook, Centropomus undecimalis (Bloch, 1792), were obtained under controlled laboratory conditions in two experiments. In the first experiment (60 days), juveniles (initially 2.9 g) maintained at 26.6degreesC were fed one of four isocaloric experimental diets containing different protein levels (diet A = 28.8%, diet B = 40.4%, diet C = 53.4%, and diet D = 65.8%). Shrimp-, soybean-, and fish-meal were used as protein sources. Best growth, specific growth rate, and feed conversion ratio were obtained with diets B, C, and D. There Were no significant differences (P > 0.05) among these three treatments. Protein efficiency ratio decreased as the level of dietary protein increased and was highest for fish fed diet A. In the second experiment (65 days), the effects of three different commercial pellets (for tilapia, catfish, and trout) and diet C were determined on snook (initially 22.7 g) at 29.1degreesC. There was no significant difference in fish weight gain between diet C and trout pellets. Significantly higher (P < 0.05) weight gain was achieved with diet C and trout pellets compared with that of fish fed the tilapia and catfish pellets. Specific growth rate and feed conversion ratio were best with diet C, and significant differences among all treatments were obtained. Protein efficiency ratio for fish fed diet C and trout and tilapia feeds was not significantly different. The results confirm the snook's ability to feed on pellets, its capability to adapt to dry feeds, the potential of commercial feeds for raising snook, and its relatively high dietary protein requirement

Replacement of live food with a microbound diet in feeding Litopenaeus setiferus (Burkenroad) larvae

Microbound feeds have been well accepted by shrimps and farmers in many penaeid shrimp hatcheries. The present study focused on an adequate level of replacement of Artemia nauplii and microalgae by a microbound diet for rearing Litopenaeus setiferus (Burkenroad) larvae. A microbound diet (MBD) consisting of fishmeal, squid meal, shrimp meal, yeast meal and soybean meal was used. The first experiment was designed to obtain the optimum level of MBD to complete the live feeding schedule, from Protozoea (PZ(III) ) to Mysis (M-III ). The experimental levels of the microbound diet tested were 2, 4, 6 and 8 mg MBD L-1 day(-1) . The next step was to determine the Artemia nauplii replacement level from PZ(I) to M-III by MBD. These experiments were carried out either in the presence (Experiment 2) or in the absence of algae (Experiment 3). Four replacement levels were tested: 0% (4 mg MBD L-1 day(-1) : 1 Artemia nauplii mL(-1) ), 40% (5.5 mg MBD L-1 day(-1) : 0.6 Artemia nauplii), 60% (6.5 mg MBD L-1 day(-1) : 0.4 Artemia nauplii) and 100% (8 mg MBD L-1 day(-1) : 0 Artemia nauplii). In all experiments growth, survival, development, quality index (QI) and performance index (PI), were used to determine the optimum concentration of microbound diet. Results showed that 6 mg MBD L-1 day(-1) can be recommended as a complement to live food for L. setiferus larvae from PZ(III) to M-III . In the presence of algae, maximum growth and survival may be obtained in 40-60% (5.5-6.5 mg MBD L-1 day(-1) ) of Artemia nauplii replacement levels. In the absence of algae, the Artemia nauplii replacement resulted in slower development, less salinity resistance, lower growth and lower survival than was obtained in larvae fed with algae

Growth, survival, quality and digestive enzyme activities of larval shrimp fed microencapsulated, mixed and live diets

An artificial diet for shrimp larvae was microencapsulated with a polysaccharide blend [66% gum arabic, 17% mesquite gum and 17% maltodextrin 10 dextrose equivalent (DE)]. Microencapsulated diet (MD) was fed to mysis alone, as a co-feed with the microalgae Chaetoceros cerastosporum and Tetraselmis chuii (mixed) and compared with a live diet (control) of C. cerastosporum, T. chuii and Artemia nauplii. No significant differences (P > 0.05) were detected in growth rates, development and quality indexes of larvae fed the three experimental diets. All diets supported survival percentages of >90%. Shrimp larvae fed MD and mixed diets had higher specific trypsin activity and soluble protein content than those fed live diet. Amylase activity decreased in larvae fed the mixed and MD apparently due to the carbohydrate composition of the diet. The results indicate that it is possible to substitute a live diet with a microencapsulated one (with a wall composition made up of a polysaccharide blend) in Litopenaeus vannamei mysis