NS Series Super SPO

for grow-outs

NS Series ER-49

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2nd Experiment

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Introducing:

 

N S   S E R I E S

 Mega SPO   

with

Thiobacillus denitrificans

&

Paraccocus denitrificans

for

High Density

Prawn & Fish Culture

 

 

 


 

 

4 Growth Stages  

 

Second Experiment

Effects of SPO in four growth stages of prawn (37, 50, 76, 96 day-old P. monodon juveniles)

 

 MATERIALS AND METHODS 

Transport of older prawns was done using the usual double plastic bags (50 x 70 cm.) which were filled with oxygen. Water taken from the pond where the prawn juveniles were grown was used. Bigger prawns (i.e. 76 and 96 day-old). were transported at 25 pcs./bag while the smaller ones (i.e. 37 and 50 day-old) were transported at 50 pcs./bag. To each bag were added 5 grams of NS Series SPO to maintain good water quality during the transport since the prawns were not properly conditioned (i.e. not starved for at least 12 hours) prior to transport. No mortality during transport and after 24 hours was observed. Transport time up to the experimental site was 3 hours and 10 min. coming from Nasugbu, Batangas and 4 hours and 15 min. coming from Pagbilao, Quezon. Upon arrival at the experimental site, the transported prawns were placed in 100 liter capacity tanks containing 40 liters of pond water with salinities of 20 and 18 ppt for prawns coming from Nasugbu, Batangas and Pagbilao, Quezon respectively. The set-up was provided with a moderate aeration system. The experimental animals were allowed to be conditioned to its new environment for 24 hours. They were then gradually acclimated to a water salinity of 18 ppt prior to the conduct of the experiment.

Prawn representing four growth stages as indicated below were stocked at 10 pcs. each in 24 units of 100-liter capacity tanks containing 20 liters of water at 18 ppt or an effective stocking density of 42 per square meter. the different stages of growth were designated as follows:

 


Stage of growth Source

Stage

Days of growth Source

Stage I

37 day old

Nasugbu, Batangas

Stage II

50 day old

 Pagbilao, Quezon

Stage III

76 day old 

Nasugbu, Batangas

Stage IV

96 day old

Pagbilao, Quezon

 

NS Series SPO were added at the rate of 1.19 g/tank or a dosage of 5 g/cu.m. Control lots were those without bacterial inoculation. The experimental set-up was provided with moderate aeration and pieces of nets to serve as sanctuary for the prawn during molting.  The experiment was conducted in a randomized Complete Block Design with three replicates per treatment.  Prawns were fed with SMI-President Feeds as in the first. experiment given at the following rates:

 

Stage %Body Weight Type of Feed Growth
Stage I 20% BW Starter
Stage II 20% BW Starter
Stage III 12% BW Grower
Stage V 5% BW Grower

The Designated feeding rates were divided into six equal parts and fed to the prawns at every four hour interval. To determine the activity of NS Series SPO, bacterial counts of the rearing water was taken initially and every two (2) days thereafter through the Most Probable Number (MPN) Method with Nutrient Agar as medium.

The physio-chemical parameters of the water like pH, D.O., nitrite, ammonia and total solids (fecal matter and unconsumed feeds) were likewise taken initially and every two days thereafter using the standard methods (APHA, 1976). No water change was done for the duration of the experiment which lasted for 14 days.

 RESULTS & DISCUSSION 


Nitrite level of the water (Fig.9-A&B)

Inoculation of the NS Series in the rearing medium with prawns at various stages of growth improved water quality. This is evident as early as during the first two (2) days where the nitrite levels were considerably lower (0.156 - 0.213 ppm) than in the un-inoculated control (0.483 - 0.;;63 ppm). The nitrite level was maintained at a significantly lower value in the treated lots than in the control for the duration of the experiment which lasted for two (2) weeks. (It should be noted that there was no water change during the experimental period). On the other hand, the nitrite level in the un-inoculated increased tremendously. In general, the inoculated bacteria was effective in reducing the nitrite level in the rearing medium with prawns by as much as 4~1% This became apparent on the 14th day when the nitrite level reached 2.133 ppm in the control while the medium with the bacteria had only 0.493 ppm. These data were observed in the medium where 96 day-old prawn (Stage IV) were stocked.

The effectiveness of NS Series SPO in the inoculated medium was further demonstrated by the fact that irregardless of age of prawn, the low nitrite level was maintained. This means that despite the high amount of feeds given to older prawns., the inoculated bacteria were able to degrade the uneaten feeds and metabolites such as there were no accumulation of the toxic nitrite in the medium. As the prawns got older, the higher rate of feeding resulted in greater amounts of uneaten feeds and higher rate of nitrite level in the water. This was true for both the inoculated and the un-inoculated rearing media. However, it should emphasized that the nitrite level in the prawn growing medium inoculated with NS Series SPO remained below the toxic level, (For prawn, the toxic level is greater than 5 ppm). On the other hand, the un-inoculated control reached a value of 2.13 ppm.

Statistical analysis showed that significant differences between the treated and control lots were obtained from the 2nd to the 14th day of culture for all growth stages of prawns.

Figure 2A1 & 2A2 shows Nitrite level of the rearing medium of four growth stages of prawns inoculated with NS Series SPO.


Ammonia Content of the water (Fig.l0A & B)

The same trend was observed on the effectiveness of NS Series SPO in maintaining good water quality for prawn farming.  The ammonia levels up to the 6th day of culture were relatively low and safe for the growing of prawns for both control and bacterial-inoculated lots. The values ranged from 0.073 to 0.093 ppm for the inoculated growing media with prawns at stages I to IV while that in the control without bacterial inoculation had higher values ranging from 0.413 to 0.674 ppm. Starting on the 8th day and up to 2 weeks, ammonia accumulated at very high levels for all control lots. During the same period, the bacteria inoculated media maintained an ammonia level below 1 ppm which is still considered tolerable for prawns. Except for the treated lots I which had 37 day old prawns, the ammonia levels remained well below the stress values (0.23-0.54 ppm). In contrast, the un-inoculated control lots had ammonia accumulating in the media at extremely high levels of up to 3.2 ppm.

Earlier reports of Chiu (1987) stated that prolonged exposure of prawns to 0.1 ppm NH3 -N can have adverse effects. The ammonia content of the water is dependent on pH and temperature. At higher pH values, ammonia toxicity problems becomes more serious. During the experiment, there was not much increase in the pH level for both control and treated lots (Figs. 11 A & B). However, in general, in the media inoculated with bacteria, the pH values were lower than in the control. This again is attributed to no water change and the subsequent degradation of organic matter into CO2 H2O and cell tissue by the inoculated bacteria in NS Series SPO.  

The Duncan's Multiple Range Test showed ( significant differences between control and treated lots from 4th to the 14th day of culture.

Effect on the dissolved oxygen (Figs. 12 A & B)

Both control and treated lots showed high D.O. values favorable for the growth of prawns. It should be noted however that the experiment was conducted under a semi-controlled system. This being the case, there was no photosynthetic activity going on which would increase the D.O. content in the water. Moreover, the inoculated bacteria which break down organic matter in the system, consume oxygen in the process. This would explain the lower D.O. values in the NS Series SPO inoculated treatments.

 

Effect on Prawn Survival (Fig. 13)

NS Series SPO treatment was most effective in increasing the percent survival of prawns.  This was observed in all growth stages although the effect was most pronounced for 50 day-old and 76 day-old (Stages II and III) prawns. High survival values of 96.7% and 86.67% were obtained for stages II and III respectively. For the control lots without bacterial inoculation, survival was lowest at stage III (40%) and stage II (43.3%).

Statistical analysis showed significant differences between inoculated and control lots for all the growth stages of prawns.

Total Solids

The ability of the inoculated bacteria to c decompose uneaten feeds and fecal matter (J in the growing media is shown by the total solids content in the water. The amount 1 of feed increases with age of prawns and I- this is reflected in the increasing total solids content in the growing medium with prawns at stages I to IV in the control lots.  At termination of the experiment, the growing media in the control lots were very turbid. Analysis of the total solids present showed that as much as 1.87 g/li or 1,870 ppm accumulated in the control. On the other hand, in all the NS Series SPO treated media, the water seems almost transparent. This condition demonstrates the fact that despite the increasing amount of feeds given to the prawns, the inoculated bacteria were able to decompose the feeds efficiently. The total solids content of the water with bacterial inoculation did not go beyond 0.28 g/li or 280 ppm after two (2) weeks. Based on the amount of NS Series SPO inoculated in the media which is 5 g/cu.m., the decomposition rate was computed at 117.21 mg/li/day for Stage IV on 96 day-old prawns.  Significant differences between control and treated lots occurred on the 4th day for all the growth stages of prawns based on Duncan's Multiple Range Test.

Bacterial Count (Figs. 15 A & B)

The bacterial population in the rearing media increased with time. Higher bacterial counts were obtained in the treated lots which is expected because of bacterial inoculation. The bacterial population was lower in the control lots. Moreover, the type of bacteria between the control and treated lots are assumed to be different. 

The Duncan's Multiple Range Test showed that differences in the bacterial count between treated and control lots in all growth stages of prawns are highly significant (p(0.05).

 

 


                      

 

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