Effects of varying dietary carbohydrate levels on growth performance, body composition and liver histology of Malaysian mahseer fingerlings (Tor tambroides).

We investigated the effects of four iso-nitrogenous (40% crude protein) and iso-caloric (17.6 kJ g(-1)) diets with different dietary carbohydrate levels (15%, 20%, 25% and 30%) on the growth performance, feed utilization efficiency, body composition and liver histology of Malaysian mahseer (Tor tambroides) fingerlings in a 10-week feeding trial. Fish (initial weight of 0.8?0.1 g; initial total length 4.2?0.1 cm) were fed twice daily at 4% body mass. Dietary carbohydrate level had significant effects (P<0.05) on weight gain, SGR (specific growth rate), FCR (feed conversion rate), PER (protein efficiency rate), survival percentage and all nutrient retention values (PRV, LRV, CRV, ERV). Protein, carbohydrate and gross energy composition of the fish body were also significantly differed (P<0.05) among treatments. Liver histology showed mild hepatic steatosis and hypertrophy for fishes receiving a higher dietary carbohydrate inclusion. In general, treatments with 20% and 25% dietary carbohydrate levels produced better growth results compared to the rest of the treatments. Using a second-order polynomial regression analysis model, the optimal dietary carbohydrate level of 23.4% was estimated for mahseer fingerlings. ?

Dietary lipid requirement of lemon fin barb hybrid.

The present study has been conducted to determine the optimal dietary requirement lipid of lemon fin barb hybrid fingerlings. Five isonitrogenous diets (35% protein) with graded lipid levels of 0%, 4%, 6%, 8% and 12% were fed to 225 lemon fin barb hybrid fingerlings (4.3 ? 0.5 g), which were randomly and equally distributed into twelve 60 l aquaria. The diets were randomly assigned to the aquaria in triplicates, and the feeding experiment was conducted for 10 weeks. Fish were fed at 5% body weight and the feeding ration was adjusted fortnightly. The weight gain, specific growth rate (SGR), protein efficiency ratio (PER) and feed conversion ratio (FCR) of fish fed 4% dietary lipid were significantly superior (P<0.05) than those fed with other diets, except for 6% lipid. Except for whole body moisture content, there were significant differences (P<0.05) between whole body proximate composition and nutrient retentions of fish fed with different test diets. The results showed that palmitic acid was the main saturated fatty acid (SFA), oleic acid was the predominant MUFA while arachidic acid and docosahexanoic were the major PUFAs in the muscle and liver tissue of fish. The n-3/n-6 ratio ranged from 0.66 to 2.65. From the results of this study, a dietary lipid of 4% was recommended for lemon fin barb hybrid. ?

The effects of dietary inclusion of garlic on growth performance and disease resistance of African catfish (Clarias gariepinus) fingerlings against Aeromonas hydrophila infection.

The present study aimed to investigate the effects of dietary inclusion of garlic (Allium sativum) peels and cloves on the growth performance and disease resistance of African catfish (Clarias gariepinus) fingerlings against Aeromonas hydrophila infection. Seven isonitrogenous (36% protein) experimental diets were formulated to contain graded levels of garlic (peels and cloves) at 0, 10, 20 and 30g.kg-1. Fish were fed twice a day for 12 weeks. The results demonstrated that no significant differences were observed with respect to growth performance or feed utilization efficiency (i.e., body weight gain (WG) (133 ? 0.3g), specific growth rate (SGR) (2.23 ? 0.04%), and feed conversion ratio (FCR) (1.00 ? 0.2g) of fish fed with different inclusion levels of garlic peels and cloves as compared to control group. The plasma biochemical results showed higher total protein, albumin and globulin content in control group (T1) as compared to the experimental groups, but these results were not significant. After the fish were challenged with A. hydrophila, low survival (13 %) was found in control group which was significantly lower as compared to all the treatment groups (> 35 %). Meanwhile, the highest survival (64%) was observed for fish fed with garlic cloves at 20g.kg-1 (T3). The results showed that inclusion of garlic cloves at 20 g.kg(-1) could enhance the resistance of African catfish fingerlings to A. hydrophila infection. ??

The effects of dietary inclusion of garlic on growth performance and disease resistance of African catfish (Clarias gariepinus) fingerlings against Aeromonas hydrophila infection.

The present study aimed to investigate the effects of dietary inclusion of garlic (Allium sativum) peels and cloves on the growth performance and disease resistance of African catfish (Clarias gariepinus) fingerlings against Aeromonas hydrophila infection. Seven isonitrogenous (36% protein) experimental diets were formulated to contain graded levels of garlic (peels and cloves) at 0, 10, 20 and 30g.kg-1. Fish were fed twice a day for 12 weeks. The results demonstrated that no significant differences were observed with respect to growth performance or feed utilization efficiency (i.e., body weight gain (WG) (133 ? 0.3g), specific growth rate (SGR) (2.23 ? 0.04%), and feed conversion ratio (FCR) (1.00 ? 0.2g) of fish fed with different inclusion levels of garlic peels and cloves as compared to control group. The plasma biochemical results showed higher total protein, albumin and globulin content in control group (T1) as compared to the experimental groups, but these results were not significant. After the fish were challenged with A. hydrophila, low survival (13 %) was found in control group which was significantly lower as compared to all the treatment groups (> 35 %). Meanwhile, the highest survival (64%) was observed for fish fed with garlic cloves at 20g.kg(-1) (T3). The results showed that inclusion of garlic cloves at 20 g.kg(-1) could enhance the resistance of African catfish fingerlings to A. hydrophila infection. ??

Administration of Bacillus subtilis strains in the rearing water enhances the water quality, growth performance, immune response, and resistance against Vibrio harveyi infection in juvenile white shrimp, Litopenaeus vannamei.

In this study, vegetative cell suspensions of two Bacillus subtilis strains, L10 and G1 in equal proportions, was administered at two different doses 10(5) (BM5) and 10(8) (BM8) CFU ml(-1) in the rearing water of shrimp (Litopenaeus vannamei) for eight weeks. Both probiotic groups showed a significant reduction of ammonia, nitrite and nitrate ions under in vitro and in vivo conditions. In comparison to untreated control group, final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) and digestive enzymatic activity were significantly greater in the BM5 and BM8 groups. Significant differences for survival were recorded in the BM8 group as compared to the control. Eight weeks after the start of experiment, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differences in shrimp survival between probiotic and control groups. Cumulative mortality of the control group was 80%, whereas cumulative mortality of the shrimp that had been given probiotics was 36.7% with MB8 and 50% with MB5. Subsequently, real-time RT-PCR was employed to determine the mRNA levels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and ß-1,3-glucan- binding protein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was only significantly up-regulated in the BM5 group compared to the BM8 and control groups. These results suggest that administration of B. subtilis strains in the rearing water confers beneficial effects for shrimp aquaculture, considering water quality, growth performance, digestive enzymatic activity, immune response and disease resistance.

Effects of Bacillus subtilis on the growth performance, digestive enzymes, immune gene expression and disease resistance of white shrimp, Litopenaeus vannamei.

We studied the effect of two probiotic Bacillus subtilis strains on the growth performance, digestive enzyme activity, immune gene expression and disease resistance of juvenile white shrimp (Litopenaeus vannamei). A mixture of two probiotic strains, L10 and G1 in equal proportions, was administered at two different doses 10(5) (BM5) and 10(8) (BM8) CFU g(-1) feed to shrimp for eight weeks. In comparison to untreated control group, final weight, weight gain and digestive enzyme activity were significantly greater in shrimp fed BM5 and BM8 diets. Significant differences for specific growth rate (SGR) and survival were recorded in shrimp fed BM8 diet as compared with the control; however, no significant differences were recorded for food conversion ratio (FCR) among all the experimental groups. Eight weeks after the start of the feeding period, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differences in shrimp survival between probiotic and control groups. Cumulative mortality of the control group was 63.3%, whereas cumulative mortality of the shrimp that had been given probiotics was 20.0% with BM8 and 33.3% with BM5. Subsequently, real-time PCR was employed to determine the mRNA levels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and ß-1,3-glucan-binding protein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was significantly up-regulated (P < 0.05) in the shrimp fed BM5 and BM8 diets compared to the control group. These findings demonstrate that administration of B. subtilis strains, L10 and G1, can improve growth performance and disease resistance through an enhanced immune response in shrimp.

Selection and identification of non-pathogenic bacteria isolated from fermented pickles with antagonistic properties against two shrimp pathogens.

In this study, potential probiotic strains were isolated from fermented pickles based on antagonistic activity against two shrimp pathogens (Vibrio harveyi and Vibrio parahaemolyticus). Two strains L10 and G1 were identified by biochemical tests, followed by16S ribosomal RNA gene sequence analysis as Bacillus subtilis, and characterized by PCR amplification of repetitive bacterial DNA elements (Rep-PCR). Subsequently, B. subtilis L10 and G1 strains were tested for antibacterial activity under different physical conditions, including culture medium, salinity, pH and temperature using the agar well diffusion assay. Among the different culture media, LB broth was the most suitable medium for antibacterial production. Both strains showed the highest level of antibacterial activity against two pathogens at 30 °C and 1.0% NaCl. Under the pH conditions, strain G1 showed the greatest activity against V. harveyi at pH 7.3-8.0 and against V. parahaemolyticus at pH 6.0-8.0, whereas strain L10 showed the greatest activity against two pathogens at pH 7.3. The cell-free supernatants of both strains were treated with four different enzymes in order to characterize the antibacterial substances against V. harveyi. The result showed considerable reduction of antibacterial activity for both strains, indicating the proteinaceous nature of the antibacterial substances. A wide range of tolerance to NaCl, pH and temperature was also recorded for both strains. In addition, both strains showed no virulence effect in juvenile shrimp Litopenaeus vannamei. On the basis of these results and safety of strains to L. vannamei, they may be considered for future challenge experiments in shrimp as a very promising alternative to the use of antibiotics.