Enhancement of Growth Performance of Kuruma Shrimp

 

 

Dr. Toshiaki ITAMI

October 27, 2002

 

Conclusions

The efficacy of SNG-100 and SNG-200 were examined on growth performance, toxicity and susceptibility to infection in shrimp.  Followings are the conclusions:

1. The oral administration of SNG-100 at the concentration of 0.75 mg/kg body weight /day (0.005% SNG-100 in diet at 1.5% feeding rate) remarkably enhances the growth rate of shrimp.  Growth effectiveness of the SNG-100 dose less than 0.005% in diet remained to be investigated.

2. SNG-100 and SNG-200 are at least non-toxic to the juvenile shrimp, which are generally very sensitive to the toxic materials.  SNG-100-fed groups showed the slightly better survival rate than the control, although statistical differences were not observed.

3. Feeding SNG-100 to shrimp does not increase the resistance against Vibrio harveyi infection in shrimp.  SNG-200 might increase the susceptibility of shrimp to luminous vibriosis or decrease the resistance to this bacterial infection because the SNG-200-fed groups showed higher mortality than SNG-100-fed groups and control group. 

Abstract

An attempt was made for evaluation of SNG-100 for growth performance and disease resistance against luminous vibriosis in kuruma shrimp, Maruspenaeus japonicus.  Shrimp were fed diets containing 0.01% and 0.005% of SNG-100 and 0.1% SNG-200 for about 30 days and monitored the growth performance and mortality.  Shrimp fed with 0.005% SNG-100 showed the better growth than the shrimp received control and other test feed.  The shrimp received the 0.005% SNG-100 showed the better growth than those fed with 0.01% SNG-100.  Therefore, the further study will be needed to lessen the amount of SNG-100 to increase the effectiveness of growth enhancement.  Shrimp were fed with these 4 different types of feed including control diet for 32 days and then challenged with Vibrio harveyi, which is the agents of pandemic shrimp disease in tropical area and causes serious damages there.  No difference in survival rates after the challenge was found in groups of shrimp fed with and without SNG-100 and SNG-200.  These results indicate that oral administration of 0.005% SNG-100 to shrimp enhances the growth performance and does not decrease the disease resistance against luminous vibriosis nor show the toxicity to shrimp.   

 

Introduction

M. Fudinaga and his colleagues developed the seed production technique and culture system of kuruma shrimp in the early 1960s in Japan after many groundbreaking studies over the preceding 30 years.  Their techniques have been spreading throughout the world and have helped the world shrimp culture industry grow enormously. 

Shrimp industries in the world had progressed without major disease problems until the early 1990s.  In 1985, the annual production of shrimp in the world was 210,000 tons and then increased rapidly to 920,000 tons in 1994, which is 4.3 times higher than that in 1985¹⁾.  The decrease in shrimp production in late 1980s and early 1990s was mainly due to Vibrio spp. infection, which caused opportunistic infection in shrimp weakened by stressful condition.  In 1990s, there was a drastic decrease in shrimp production due to introduction of new types of viruses and bacterial infection: yellow head virus²⁾, white spot syndrome virus (WSSV)^{3, 4)}, Taura syndrome virus⁵⁾, Vibrio harveyi.  These viruses and bacterium are still damaging the shrimp culture industries in the world.  Especially, WSSV and V. harveyi are widely spreading from Asian countries to Central and South Americas, and giving a huge negative impact to shrimp production and food processing industries in these countries, where shrimp products are extremely important for major exports to earn foreign currency. 

Post-larvae stage of the shrimp is very susceptible to viral and bacterial diseases and big mortality is usually found in this stage.  To shorten this stage by enhancing the growth by SNG-100 would provide advantages to shrimp farmers for successful harvest.  SNG-100 is extracted from Achyranthes roots that is commonly used in Korea and credited with notably tonic property.  Therefore, in this experiment we attempted to evaluate the efficacy of SNG-100 and its mixture for shrimp growth.

 

Materials and Methods

 

[Growth Performance Trials]

Shrimp: Kuruma shrimp, Penaeus japonicus, were used.  Average body weights of the animal used for growth test were 8.8 and 5.8 g.  Shrimp were kept for 2 weeks for acclamation in our facility before the test diets were fed.  During the acclamation period, control diet was fed.

Diet: The basic composition of diet was "Ebian-Kyowa" for adult kuruma shrimp, M. japonicus.  Four different types of dry pellet were manufactured; 0.1% SNG-200, 0.01% SNG-100, 0.005% SNG-100 in the diet and control diet without additives.  Following are the content of the additives per kg body weight of shrimp per day when 0 - 0.1% SNG-100 or SNG-200 diet is fed at 1.5% feeding rate. 

 

Additives in diet (%)	0%	0.1% SNG-200	0.01% SNG-100	0.005% SNG-100
mg/kg shrimp body weight/day	0	15	1.5	0.75

Test group: Four groups of shrimp were set: Control (0%), 0.1% SNG-200-fed group, 0.01% SNG-100-fed group, 0.005% SNG-100-fed group.  Each group had 10 shrimp.

Feeding schedule: Diets were fed every day for about 4 weeks. Feeding frequency was one time a day (6:00 pm). 

Rearing condition: Shrimp were kept in 50 litter holding tank. Water temperature was 25 Celcius.. 

Measuring factors: Mean body weight (± SD) with a week interval (initial body weight, final body weight), mortality during the test period and number of molted carapace

 

[Toxicity Test]

 

Shrimp: The shrimp whose weight was 2.0 g at the beginning of the trial were used.

Diets: Four types of dry pellet mentioned in the previous section were fed to the shrimp.

Test groups: Four groups of shrimp, which were Control (0%), 0.1% SNG-200-fed group, 0.01% SNG-100-fed group, 0.005% SNG-100-fed group same as in the previous section, were set.  Each group has 30 shrimp.

Feeding schedule: The test diets were fed everyday for 4 weeks. 

Rearing condition: Shrimp were kept in 50 litter holding tank.  Water temperature was 25 Celcius. 

Measuring factors: Mortality during the test period 

[Resistance against Luminous Vibrio Infection in Kuruma Shrimp]

Shrimp: The shrimp whose weight was 5.8 g at the beginning of the trial were used.

Diets: Four types of dry pellet mentioned in the previous section were fed to the shrimp.

Test groups: Four groups of shrimp, which were Control (0%), 0.1% SNG-200-fed group, 0.01% SNG-100-fed group, 0.005% SNG-100-fed group same as in the previous section, were set.  Each group has 9-10 shrimp.

Feeding schedule: The test diets were fed everyday for 32 days before the challenge and 10 days after the challenge. 

Rearing condition: Shrimp were kept in 50 litter holding tank.  Water temperature was 25±1°C. 

Challenge trial: Twelve-hours culture of Vibrio harveyi was harvested in 50% sterile seawater and injected into the 2nd muscle segment at concentration of 8.8´10⁶ and 1.7´10⁶ cfu/shrimp.  After the injection, the shrimp were transferred back to the 50-litter holding tanks.  The mortality was observed for 10 days after the challenge. 

Measuring factors: Mortality after the challenge, reisolation of luminous bacteria on the seawater-based nutrient agar. 

 

Results and Discussion

[Growth Performance Trials]

Fig. 1 shows the growth curve of shrimp fed with SNG-100 and SNG-200 at different concentrations in the 1st trial using 8.8 g of shrimp.  Shrimp fed with 0.005% SNG-100 showed the remarkably higher growth rate than 0.01% SNG-100-fed group, 0.1% SNG-200-fed group and control group.  The difference of average body weight was observed on the 2nd week and biggest difference was found on the 3rd week, when the difference in average body weight between 0.005% SNG-100-fed group and control was 0.8 g.  Growing rate of 0.005% SNG-100-fed group from the day 21 to 28 decreased because of the high stocking density in the holding tank. 

In the 2nd trial of growth test, duplicated groups were set. Each group had 10 shrimp.  Fig. 2 and 3 show the changes of weight gain of shrimp fed with control diet and test diets.  Fig. 2 shows the results of duplicated tests and Fig 3 is averages of these results.  In Fig. 2, changes of two groups of 0.005% SNG-100-fed shrimp showed the same trend and the weight gain of these groups is higher than other groups.  Therefore, this result demonstrates the effectiveness of oral administration of 0.005% SNG-100 for growth enhancement of shrimp, supporting the results shown in Fig. 1.  The difference of body weight gain between 0.005% SNG-100-fed group and control is 0.34 g at the termination of the experiments.  There is no difference among 0.1% SNG-200-fed group, 0.01% SNG-100-fed group and control group as well as found in the 1st experiment. 

 

 

[Toxicity Test]

Juvenile shrimp (weight: 2.0g, 30 shrimp/group) were fed with above-mentioned 3 types of test diet and control diet for 33 days every day and survival rates was examined. At the termination of the tests, survival rate of Control, 0.1% SNG-200-fed group, 0.01% SNG-100-fed group and 0.005% SNG-100-fed group were 90.0, 96.7, 100 and 100% respectively (Table 1).  These results demonstrate that SNG-100 and SNG-200 are at least non-toxic to the juvenile shrimp that are generally sensitive to the toxic materials, and SNG-100-fed groups showed the slightly better survival rate than the control, although statistical differences were not observed. 

Table 1.  Survival rates of juvenile kuruma shrimp (2.0 g) after oral administration of test diets and control diet for 33 days.

	Control	0.1% SNG-200	0.01% SNG-100	0.005% SNG-100
Survival rate (%)	90.0	96.7	100	100
No. survivors/No. tested	27/30	29/30	30/30	30/30

 

 [Resistance against Luminous Vibrio Infection in Kuruma Shrimp]

Shrimp that received the test diets and control diet were challenged with V. haveyi at a concentration of 8.8´10⁶ and 1.7´10⁶ cfu/shrimp.  Mortality was recorded and bacterial isolation from the dead shrimp was carried out for confirmation of the infectious agents.  Table 2 shows the survival rates of challenged shrimp.  When the shrimp were challenged with 8.8´10⁶ cfu/shrimp, no difference was found in the mortality of the shrimp between test diets and control diets.  When shrimp were challenged with lower concentration of bacteria (1.7´10⁶ cfu/shrimp), shrimp fed with 0.1% SNG-200 showed slightly higher mortality than SNG-100-fed groups and control, and no difference was found between SNG-100-fed group and control (Fig. 4).  These results may indicate that SNG-200 might increase the susceptibility of shrimp to luminous vibriosis or decrease the resistance to the bacterial infection.  SNG-100 does not have side effect of increasing susceptibility to infection since the differences in mortality between SNG-100-fed group and control group were not found after the challenge, although the prophylactic effect against Vibrio infection was not found

 

Table 2. Survival rates of shrimp fed with test diets and control after challenged with Vibrio harveyi. 

		Control	0.1% SNG-200	0.01% SNG-100	0.005% SNG-100
8.8´106 cfu/shrimp	Survival rate (%)	20%	10%	10%	20%
	No survivors/ No. tested	2/10	1/10	1/10	2/10
1.7´106 cfu/shrimp	Survival rate (%)	80%	50%	89%	78%
	No. survivors/ No. tested	8/10	5/10	8/9	7/9

 

 

Fig. 4.  Survival rates of shrimp fed with 0.1% SNG-200, 0.01% SNG-100, 0.005% SNG-100 and control diet after the challenge with Vibrio harveyi

 

References

1)      Food and Agriculture Organization (1996): FAO Fisheries Circular, No. 815, Rev., 8, Rome<>, pp. 1-188.

2)      Boonyaratpalin, S., K. Supamattaya, J. Kasornchandra and C. Chantanachooklin (1993): Non-occluded baculo-like virus, the causative agents of yellow head disease in the black tiger shrimp (Penaeus monodon).  Fish Pathology, 28, 103-109.

3)      Takahashi, Y., T. Itami, M. Kondo, M. Maeda, R. Fujii, S. Tomonaga^, K. Supamattaya and S. Boonyaratpalin<> (1994): Electron Microscopic Evidence of Baculo-like Virus Infection in Kuruma Shrimp (Penaeus japonicus). Fish Pathology, 29, 121-125.

4)      Y. Takahashi, T. Itami, M. Maeda, N. Suzuki, J. Kasornchandra, K. Supamattaya, R. Khongparadit, S. Boonyaratpalin , M. Kondo, K. Kawai, R. Kusuda, I. Hirono and T. Aoki (1996): Polymerase chain reaction (PCR) amplification of bacilliform virus (RV-PJ) DNA in Penaeid japonicus Bate and systemic ectodermal mesodermal baculovirus (SEMBV) DNA in Penaeus monodon Fabricius.  Journal of Fish Diseases, 19, 399-403.

5)      Lightner, D. V. (1996): A handbook of pathology and diagnostic procedures for diseases of penaeid shrimp.  World Aquaculture Soc., Baton Rouge, Luisiana, Section 3.11.