Body Weight Specific Growth Rate Research Articles

Heterosis of the interspecific sea urchin hybrids between Strongylocentrotus intermedius and Heliocidaris crassispina

In order to study the heterosis of the interspecific hybrids between sea urchin Strongylocentrotus intermedius and Heliocidaris crassispina, comparative culturing experiments were conducted on individuals of the same age from four groups: S. intermedius (SI), H. crassispina (HC), S. intermedius ♀ × H. crassispina ♂ (SH), and H. crassispina ♀ × S. intermedius ♂ (HS). Growth rate at different stages of development, gonadal production and quality, high-temperature tolerance, and resistance to black-mouth disease were compared among these four species. The results were as follows: in the juvenile sea urchin stage, SH sea urchins exhibited 79.11% and 55.28% body weight heterosis at 16 and 20 °C, respectively, with particularly high single-parent heterosis observed at 16 °C compared to the male parent HC (247.79%). In the young sea urchin stage, SH sea urchins displayed mid-parent heterosis in body weight at all temperatures except 28 °C, reaching a maximum of 94.62% at 12 °C. HS Sea urchins showed mid-parent heterosis only at 12, 24, and 28 °C, with the highest observed at 28 °C (36.51%). The body weight specific growth rate of SH sea urchins was significantly higher than those of the other three species (P < 0.05), and they achieved the largest body weight (48.43 g) by the end of the experiment. The gonad wet weight of SH sea urchins was significantly higher than those of the other three species (P < 0.05). While there was no difference in gonad index between SH and SI sea urchins, it was significantly higher than those of HC and HS sea urchins. In terms of high-temperature tolerance, the upper thermal tolerances (UTT) of HC and HS sea urchins were significantly higher than those of SI and SH sea urchins (P < 0.05). Regarding resistance to black-mouth disease, there was no statistically significant difference in survival rates between SH sea urchins and SI sea urchins after infection with Vibrio echinoideorum at a concentration of 1 cfu/mL. However, the survival rate of HS sea urchins was significantly higher than that of SI. The study demonstrated that the SH hybrid sea urchins exhibit notable advantages in growth and gonad yield compared to its parental species, suggesting its potential as a valuable candidate for the cultivation of new sea urchin varieties in aquaculture. These findings hold significant promise for enhancing the efficiency and sustainability of sea urchin farming practices.

Effects of the probiotic Bacillus amyloliquefaciens on the growth, immunity, and disease resistance of Haliotis discus hannai

The effects of a diet containing the probiotic Bacillus amyloliquefaciens on the survival and growth of Haliotis discus hannai were evaluated by measuring growth and hematological parameters and the expression levels of nonspecific immune genes. In addition, the abalone's response to Vibrio parahaemolyticus infection was assessed. H. discus hannai (shell length: 29.35 ± 1.81 mm, body weight: 4.28 ± 0.23 g) were exposed to an 8-week culture experiment in indoor aquariums and a 2-week V. parahaemolyticus artificial infection experiment. In each experiment, the control group (C) was fed daily with the basal feed; the experimental groups were fed daily with the experimental feed, prepared by spraying B. amyloliquefaciens onto the basal feed at final concentrations of 103 (group A1), 105 (A2), and 107 (A3) cfu/g. The survival rate, body weight specific growth rate, and food conversion efficiency in A2 and A3 were significantly higher than those in A1 and C (P < 0.05). The total number of blood lymphocytes, the O2− and NO levels produced from respiratory burst, the activities of acid phosphatase, superoxide dismutase, and catalase, and the expression levels of catalase and thiol peroxidase in A2 were not significantly different from those in A3, but these factors were significantly higher in A2 compared to A1 and C (P < 0.05). The total antioxidant capacity and expression levels of glutathione S-transferase in A1, A2 and A3 were significantly higher than those in C (P < 0.05). At day 9 after infection with V. parahaemolyticus, all abalone in C were dead; at the end of the experiment, the cumulative mortality of abalone in A2 was significantly lower than that in any other group (P < 0.05). Thus, the experimental feed containing 105 cfu/g B. amyloliquefaciens not only facilitated the food intake and growth of abalone, but also effectively enhanced their non-specific immunity and resistance to V. parahaemolyticus infection. In this regard, B. amyloliquefaciens may be a useful probiotic strain for abalone aquaculture.

Effects of flow velocity on growth, metabolism and nitrogen and phosphorus budget of Haliotis discus hannai Ino in a recirculating aquaculture system

To study the effects of different flow velocities on growth, metabolism and nitrogen (N) and phosphorus (P) budget of Haliotis discus hannai Ino in a recirculating aquaculture system, abalones (shell length: 45.71 ± 3.09 mm, body weight: 8.62 ± 0.75 g) were cultured at three different flow velocities with four replicates each: high (400 L/hr), medium (300 L/hr) and low (200 L/hr). At the end of the 70 days experiment, the survival rate, food intake and P utilization rate of abalones in the 200 L/hr group were significantly lower than those in any other group (p < .05), whereas the total ammonia nitrogen and nitrite nitrogen concentrations in the water were significantly higher than those in any other group (p < .05). The body weight specific growth rate, food conversion efficiency, abalone-harvested N and P outputs and N utilization rate were ranked as follows: 300 > 400 > 200 L/hr (p < .05). In the 300 L/hr group, the activities of hexokinase, pyruvate kinase and lactate dehydrogenase were significantly lower than those in the 400 L/hr group, whereas the activity of succinate dehydrogenase was significantly higher than that in the other two groups (p < .05). Aerobic metabolism was the main source of energy acquisition for abalones in the 300 L/hr group. In the 400 L/hr group, the expression levels of manganese superoxide dismutase and thioredoxin peroxidase significantly increased from Day 35 to Day 70, but they still were significantly lower than the values in the 200 L/hr group (p < .05). In the 200 L/hr group, the expression levels of catalase and heat shock protein 70 were significantly higher than those in any other group, and they significantly increased from Day 35 to Day 70 (p < .05). These results indicate that maintaining flow velocity at 300 L/hr will minimize oxidative damage due to deterioration of water quality, reduce the energy consumption required for organisms to resist the impact of water flow, improve the N and P utilization rates of the recirculating aquaculture system, and reduce the cost of culturing abalones.

Effects of upstream exercise training on feeding efficiency, growth and nutritional components of juvenile tinfoilbarbs(Barbodes schwanenfeldi)

The objective of this study was to determine the impact of upstream exercise training on feeding efficiency,growth,and nutritional components of juvenile tinfoil barb Barbodes schwanenfeldi(weight 75.21±2.82 g).The experiment included two stages,1-23 d and 23-45 d.After water current treatment(0 BL/s,0.7 BL/s,2.0 BL/s)for 45 d,the daily feeding ratio(FR)increased significantly with increasing water velocities.The maximum values of the body weight specific growth rate(SGR),body length SGR and feed conversion rate(FCR)were in the water current of 0.7 BL/s,the second maximum values of those were in 0 BL/s and the minimum values were in 2.0 BL/s,with significant differences among the three(P0.05).No significant difference in crude ash and water contents in muscles was observed among the treatments with various water velocities(P0.05).The protein contents of fish muscles increased greatly with the increase of water velocities,while the lipid contents of muscles dropped with increasing water velocities.At the end of the experiment,the contents of total amino acid(TAA),essential amino acid(EAA),and delicious amino acid of the fish treated with the water velocities of 2.0 BL/s were 82.63%,34.34%,and 33.50%,respectively,being significantly higher than respective values of controls(78.27%,32.6%,30.63%)(P0.05).Our result indicated that the lower water currents(0.7 BL/s)could effectively promote growth of juvenile tinfoil barb,improve feed conversion rates,and increase protein contents of fish muscles.The exercise training under the high flow(2.0 BL/s)was unsuitable to growth,but it could increase the contents of EAA and delicious amino acids in muscles of juvenile tinfoil barb.The result could provide basis to improve culturing conditions and nutritional quality of tinfoil barb B.schwanenfeldi.