Jiangang Wang

Selection of diet for culture of juvenile silver pomfret, Pampus argenteus

Juvenile silver pomfret, Pampus argenteus, was grown in culture tanks for 9 weeks on four different diets, and their effects on fish growth, digestive enzyme activity, and body composition were assessed. The feeding regime was as follows: Diet 1: fish meat; Diet 2: fish meat+artificial feed; Diet 3: fish meat+artificial feed+Agamaki clam meat; Diet 4: fish meat+artificial feed+Agamaki clam+copepods. The greatest weight gain was associated with Diet 4, while the lowest weight gain was associated with Diet 1. No significant difference was observed in weight gain between fish receiving Diet 2 and Diet 3. Specific growth rate followed similar trends as weight gain. The feed conversion ratio (FCR) of fish fed Diet 1 was significantly higher than the other fish groups, but no significant differences were observed in FCRs of fish fed Diet 2, Diet 3 or Diet 4. There was also no significant difference in the hepatosomatic index (HSI) between the four diets. For fish that received Diets 2-4, containing artificial feed, higher protease activities were detected. A higher lipid content of the experimental diets also significantly increased lipase activities and body lipid content. No significant differences in amylase activity or body protein content were found between Diets 1–4. In conclusion, a variety of food components, including copepods and artificial feed, in the diet of silver pomfret significantly increased digestive enzyme activity and could improve growth performance.

Influence of dietary n-3 LC-PUFA on growth, nutritional composition and immune function in marine fish Sebastiscus marmoratus

A 60-day feeding experiment was conducted to investigate the influence of dietary omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) on growth, nutritional composition and immune function of marine fish Sebastiscus marmoratus. Five diets containing 3.6, 10.2, 18.2, 26.5, or 37.0 g/kg n-3 LC-PUFA were prepared. The results reveal significant influences of dietary n-3 LC-PUFA on the final weight, weight gain, specific growth rate, feed conversion ratio, and condition factor. As dietary n-3 LCPUFA increased, weight gain and specific growth rate increased and were significantly higher in groups fed 18.2, 26.5 and 37.0 g/kg than in groups fed 3.6 and 10.2 g/kg (P<0.05); there was no significant difference between groups fed 18.2, 26.5, or 37.0 g/kg (P>0.05). With increasing dietary n-3 LC-PUFA, eicosapentaenoic acid and docosahexenoic acid content in muscle and liver increased significantly, immunoglobulin class M content gradually increased from 9.1 to 14.8 μg/L, and lysozyme activity content increased from 1 355 to 2 268 U/mL. Broken line model analysis according to weight gain indicated that a dietary n-3 LC-PUFA level of 18.2 g/kg is essential for normal growth at a fat level of 125 g/kg. Therefore, appropriate dietary n-3 LC-PUFA not only promote growth and improve the n-3 LC-PUFA content, but also enhance immune function in S. marmoratus.

Optimum Water Temperature for the Growth of Juvenile Common Chinese Cuttlefish, Sepiella maindroni (De Rochebrune 1884)

ABSTRACT The current study was carried out to investigate the influence of water temperature on growth and activity of the digestive enzymes pepsin, trypsin, lipase, and amylase in common Chinese cuttlefish (Sepiella maindroni de Rochebrune). Triplicate groups of S. maindroni (weight ± SD, 4.08 ± 0.26 g; mantle length, 31.37 ± 1.04 mm) were reared at different water temperatures (16°C, 20°C, 24°C, 28°C, and 32°C). S. maindroni instantaneous growth rate (IGR), feeding rate (FR), food conversion (FC), and mantle length increase (ML) were significantly affected by water temperatures. Regression relationships between water temperature and IGR = -0.026T2 + 1.359T - 12.63 (n = 15, R 2 = 0.995); FR = -0.064T2 + 3.465T - 25.69 (n = 15, R 2 = 0.971), FC = -0.069T2 + 3.55T - 25.01 (n = 15, R 2 = 0.983); and ML = -0.238T2 + 12.27T - 123.9 (n = 15, R 2 = 0.992). The optimum temperatures for IGR, FR, FC, and ML were 26.13°C, 27.07°C, 25.72°C, and 25.78°C, respectively. Survival was greatest at 24°C and 28°C (>95%), and was significantly higher than other temperatures. Digestive enzyme activities were highest at 24°C or 28°C, and were significantly higher than at 16°C. In conclusion, the optimum temperature for growth of S. maindroni is 25–27°C based on IGR, FR, FC, and digestive enzyme activities at different temperatures.

Effects of dietary lipid levels on serum biochemistry indices, immunity, and antioxidant activity in Sebastiscus marmoratus : Effects of dietary lipid levels on serum biochemistry indices, immunity, and antioxidant activity in Sebastiscus marmoratus

We evaluated the effects of dietary lipid levels on serum biochemistry indices,immunity,and antioxidant function in Sebastiscus marmoratus.Juvenile fish(average initial body weight: 27.56±0.19 g) were randomly divided into 5 groups and fed diets containing different levels of lipid(from fish meal) for 60 d: diet A(6.1%),diet B(9.5%),diet C(12.4%),diet D(15.1%),or diet E(18.5).The HDL-C content tended to increase with increasing dietary lipid levels.HDL-C levels were highest in the fish fed diet E and were significantly higher than in fish fed diets A–C(P0.05).The LDL-C content also tended to increase at first but then decreased at higher dietary lipid levels.The LDL-C content was significantly higher in fish fed diet C than those fed diets D and E(P0.05).TG and CHO content tended to decrease as dietary lipid levels increased.TG and CHO content were significantly lower in fish fed diets D and E than in those fed diets A-C(P0.05).Diet had no effect on TP(P0.05).The IgM content tended to increase then decrease with increasing dietary lipid levels.IgM levels were significantly higher in fish fed diet C than all other groups.Similarly,LZM levels increased then decreased with increasing dietary lipid levels and were significantly higher in fish fed diet C than those fed diets A,D,and E.The liver SOD,CAT, and T-AOC activity also increased then decreased with increasing dietary lipid levels.Enzyme activity was highest in fish fed diet C than all other groups.The liver MDA content increased with increasing dietary lipid levels and was higher in fish fed diets D and E than those fed diets A.C(P0.05).Serum SOD activity also increased with increasing dietary lipid levels and was higher in fish fed diets D and E than those fed diets A.C(P0.05).Last, serum CAT activity tended to increase but there was no difference among the groups(P0.05).In conclusion,the adaptability of S.marmoratus to the dietary lipid levels is reflected by changes in serum biochemistry.Our data suggest the optimal dietary lipid levels(12.4%) are associated with improved immunity and antioxidant function.

Effects of salinity on serum osmolality,catalase and gill ion-regulatory enzyme activities in silver pomfret

The juvenile silver pomfret were cultured in water with salinity 14,25 and 36,respectively,for 96h. And their serum osmolality,catalase( CAT) and gill V-H+-ATPase( VHA),Ca2 +-ATPase,carbonic anhydrase( CA) activities w ere tested in different salinity over time in this experiment. In this study,the serum osmolality w hich fluctuated w as positively correlated to salinity,and its variation range is 271- 379mOsm / kg. The serum osmolality of different salinity w ould return to normal at 96 h. CAT activities of salinity 36 and 14 returned to normal after they rose significantly( P 0. 05); the highest point of them w as salinity 36 at 8 h. VHA activities rose,then recovered in salinity 14,kept stable in control salinity,fell dow n then recovered in salinity 36. Ca2 +-ATPase activities increased significantly w hen salinity changed( P 0. 05),and the variation trend in salinity 14 w as more identifiable than that in salinity 36. CA activities in salinity 14 and 36 both increased significantly( P 0. 05),and the highest point w as found in salinity 36 at24 h. Through analysis of the data,the serum osmolality w as significantly negatively correlated to gill VHA activity( P 0. 01),and it w as significantly negatively correlated to CA activity( P 0. 01) in low salinity adaptation( 14 and 25). It also illustrated a contrary trend betw een serum osmolality and Ca2 +-ATPase activity in salinity 14. This research proved that serum osmolality w hich changes w ith salinity,w ill activate CAT w hen silver pomfret adapts to different salinity. And VHA,Ca2 +-ATPase and CA are playing important roles in osmoregulation.