Search

Guava (Psidium guajava L.) leaf extracts have antiviral and antibacterial activity against shrimp pathogens such as yellow-head virus (YHV), white spot syndrome virus (WSSV), and Vibrio harveyi, which make it a potential water disinfectant for use in shrimp culture. In this study, the safety of guava leaf supplementation in shrimp was evaluated by studying its influence on growth and the non-specific immune response of Penaeus monodon. Six diets containing different levels of guava leaves (0% [basal diet], 0.025% [G1], 0.05% [G2], 0.1% [G3], 0.2% [G4], and 0.4% [G5]) were fed to groups of shrimp (1.576 ± 0.011 g body weight) in triplicate for 56 days. Growth performance (final body weight, WG, PWG, SGR) of shrimp fed guava leaf diets was significantly higher (P0.05) than that of shrimp fed on the basal diet. The G1 diet resulted in the highest body weight gain (308.44%), followed by the G2 (295.45%), G3 (283.05%), G5 (281.29%), G4 (276.11%), and finally the basal diet (214.58%). Survival of shrimp in the G1 diet group was higher than that of shrimp in the control and the other experimental groups; however, no statistical differences (P0.05) were found. Dietary supplementation with guava leaf improved the activities of prophenoloxidase (PO) and nitric oxide synthase (NOS) in serum, and of superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LSZ) both in serum and hepatopancreas of shrimp. In the experimental groups, the activities of these enzymes followed a similar pattern of change; they increased initially at low levels of dietary supplementation and then decreased with increasing concentrations of dietary guava leaf. Serum PO and SOD activities in shrimp fed the G1 diet reached 7.50 U ml(-1) and 178.33 U ml(-1), respectively, with PO activity being significantly higher than in controls. In shrimp fed the G1 diet, SOD, ACP, and AKP activities in hepatopancreas were significantly higher than in the controls, reaching 57.32 U g(-1), 23.28 U g(-1), and 19.35 U g(-1) protein, respectively. The highest activities of serum ACP, AKP, LSZ, and of hepatopancreas LSZ, were observed in the G3 diet group. Total nitric oxide synthase (TNOS) activity was highest (64.80 U ml(-1)) in the G4 diet group, which was significantly higher than that observed in the control group. These results suggest that dietary guava leaf supplementation could enhance the growth performance and non-specific immune response of P. monodon. Therefore, guava leaf is considered safe for use as a water disinfectant in shrimp culture.

In South China, certain problems exist in some of aquaculture pond ecosystems, where the concentrations of total phosphorus are high in the sediment but the concentrations of phosphate are low in the overlying water. It is very important and necessary to isolate and screen some phosphate-solubilizing bacteria (PSB) that can adapt to the pond environment for enhancing the utilization of phosphorus in the aquaculture systems. To reach the objective, one PSB, named g6, was isolated using modified Pikovskaya and Pikovskaya medium. By 16S rDNA sequencing analysis and BIOLOG auto-identification system, this strain was identified as Pantoea stewartii subsp. stewartii. After 144 h strains cultivation in liquid National Botanical Research Institute’s phosphate growth medium, its activity resulted in accumulations of soluble phosphate 543 mg l−1. Based on the aquaculture pond ecosystems in South China, effects of temperature, salinity, and pH on g6’s growth were also conducted under indoor culture conditions. Results indicated that Pantoea stewartii subsp. stewartii g6 could tolerate wide range of temperature 15–35°C, salinity 5–35‰, and initial pH 6–10. The results showed that g6 had high solubilization efficiency in vitro and could be expected to adapt well to different aquaculture pond environments, based on culture results.

The basal diet (C), with 0.20% medicinal herbs (M) and 0.30% Bacillus (BM1), with 0.10% medicinal herbs and 0.15% Bacillus (BM2), and with 0.30% Bacillus (B), was used to feed white shrimps (Litopenaeus vannamei) (1.91 ± 0.03 g) in order to assess survival, growth, body composition, and digestive enzyme activity. At the end of the feeding trial, survival ranged from 95.83 to 98.33% with no significant difference (P > 0.05) among all groups. Growth measured as weight gain was significantly (P < 0.05) higher in shrimp fed with BM2, BM1, and M compared to that of C. However, no significant differences were found among B, BM1, and M. In the case of specific growth rate, the shrimp fed with BM1 and BM2 exhibited significantly (P < 0.05) higher values than that of C. The contents of body moisture, crude protein, and ash seemed to be unaffected by the feed supplements, though lipid content was found to be significantly (P < 0.05) different among the treatments. The shrimp fed with BM1 and BM2 had the lowest and highest lipid contents, respectively. The digestive enzyme activity assessed using shrimp hepatopancreas revealed that the activities of amylase and protease in shrimp fed with BM2 were significantly (P < 0.05) higher than those of C at the end of the 2nd and 6th weeks. However, better performance of the specific amylase activity was shown by the shrimp fed with B at the end of the 8th week.

White shrimp (Litopenaeus vannamei) was fed six different formulations of medicinal herbs (MH) and Bacillus in a feeding trial conducted for 56 days. The survival, growth, digestive enzyme activity, and serum biochemical parameters were assessed. A basal diet without MH and Bacillus was served as the control. At the end of feeding trial, survival ranged from 76.19% to 84.76% with no significant differences (P > 0.05) among all groups. Growth measured as final weight, specific growth rate (SGR), protein efficiency ratio (PER), protein productive value (PPV), and feed efficiency ratio (FER) were improved with increased dietary MH and Bacillus. Shrimp fed 0.2% MH and 0.3% Bacillus (Diet 23) were found to have the best growth performance. For shrimp fed Diet 23 final weight and SGR were significantly (P 0.05) in serum Triacylglycerols between supplemented groups and control was found. Results revealed that the combined MH and Bacillus in diet could enhance growth because it can improve digestive enzyme activity and digestive metabolism.

Apparent digestibility coefficients (ADCs) of crude protein (CP), lipid, phosphorus, essential amino acids (EAA), non-essential amino acids (NEAA) and fatty acids were determined for white shrimp ( Litopenaeus vannamei ). One type of traditional Chinese medicine (TCM) comprising a mixture of equal proportions of six herbs and plant materials was used at 0, 0.5, 1.0, 2.0, 4.0 and 8.0 g kg −1 in the six experimental diets. ADCs were determined using 0.01% Y 2 O 3 as an indicator. A total of 450 shrimp (initial mean body weight 8.6±0.5 g) were randomly stocked into 18 500 l outdoor concrete tanks. Feces were collected from three replicate groups of shrimp. ADCs of six diets were: CP, 88.39–91.30%; lipid, 61.63–74.36%; phosphorus, 45.38–47.29%; EAA, 90.37–93.28%; NEAA, 89.73–92.10%; saturated fatty acids (SFA), 54.35–66.03%; monounsaturated fatty acids (MUFA), 61.36–77.56%; and polyunsaturated fatty acids (PUFA)+highly unsaturated fatty acids (HUFA), 61.33–85.20%. ADCs of CP decreased as TCM increased. However, ADCs of lipid and phosphorus increased as TCM increased except for the diet containing TCM 8.0 g kg −1 . AA and fatty acids availability values for test diets followed a similar trend to values of CP and lipid.