Analysis of feed management on vannamei shrimp (Litopenaues vannamei) enlargement in BBPBAP Jepara

Many people are interested in shrimp farming because the large profits. One type of shrimp that is often exported is vannamei shrimp. This study aimed to analysis the feed management of vannamei shrimp at BBPBAP Jepara. The working method used in this study was descriptive method by utilizing primary and secondary data. There were 3 ponds observed, namely A51 (268,500 density), A52 (292,000 density) and A61 (399,000 density). Observation time until shrimp is harvested. The method of feeding was to spread the feed evenly to the pond by walking around the pond plot. The percentage of white snapper nursery in the form of seed survival rate at harvest was 80%, feed conversion ratio was 1.51. The average results of water quality parameters in white snapper fish rearing ponds included salinity ranging from 30-35 ppt, DO ranging from 3.2-3.8 mg/L, and water temperature ranging from 28.6-32.6 °C. It could be concluded the white snapper nursery in BBPBAP Jepara showed good results.


Introduction
Many people are interested in shrimp farming because the profits are very large. One type of shrimp that is often exported is vannamei shrimp. The demand for vannamei shrimp is very large, both in the national and international markets [1]. This is because vannamei shrimp has the advantage of very high nutritional value and has a fairly high economic value [2]. According to data from the Central Statistics Agency, Indonesia is able to produce vannamei shrimp for export of nearly 110,000 tons or around 930 million US dollars). In 2018, the export shrimp commodity is in second place based on the number, therefore many are cultivating it.
The factor that plays an important role in determining the success of aquaculture is feed. Feed as the largest component in financing will determine the success of cultivation [3]. Efficient use of feed in aquaculture is very important because feed is the most expensive production factor. This is because the price of feed ingredients has increased from year to year. Therefore, efforts to improve the composition of nutrients and improve the efficiency of feed use need to be carried out in order to increase the production of cultivated products and reduce the cost of procuring feed and minimize the production of waste in the cultivation media. To achieve this goal, feed management is needed to understand the nutrition and nutrient requirements of the cultivar, feed manufacturing technology, and the ability to manage feed for each type of cultivation of a particular cultivar [4]. This feed management must adapt to the needs of vannamei shrimp feed both from larvae to rearing / brooders.
The Center for Brackish Water Cultivation Fisheries or BBPBAP Jepara is a Technical Implementation Unit (UPT) of the Directorate General of Aquaculture, the Ministry of Marine Affairs and Fisheries, which started its activities in 1971. One of the commodities in BBPBAP Jepara is vannamei shrimp, be it hatchery or grow-out. The development of vannamei shrimp culture technology at BBPBAP Jepara is quite advanced and is included in the ranks of a very good brackish water aquaculture center. This study aims to determine the feed management in BBPBAP Jepara.

Research design
The working method used in this study was descriptive method by utilizing primary and secondary data [5]. There were 3 ponds observed, namely A51 (268,500 density), A52 (292,000 density) and A61 (399,000 density). Observation time until shrimp is harvested.

Research parameter calculation
The parameters tested in this study were ABW (Avegare Body Weight), FCR (Feed Conversion Rate) and SR (Survival Rate). Average body weight could be seen in the following formula [5]: The number of dead fish was counted every day until the end of the study. According to previous study the survival rate of fish was calculated using the formula [6]: : Final number of fish (fishes) N0 : Initial number of fish (fishes) FCR was calculated by using the formula [7]: The water parameter quality measured in this study were salinity, temperature and DO (Dissolved Oxygen). Temperature and DO measurements use a DO meter, while salinity measurements use a refractometer.

Results and discussion
During the study, sampling was conducted four times. In the first sampling, the results obtained were ABW in A51 ponds weighing 3.2 grams, A52 ponds weighing 4.9 grams, A61 ponds weighing 4.25 grams. The second sampling resulted in the ABW of the A51 ponds weighing 4.7 grams, the A52 ponds weighing 6.82 grams, and the A61 ponds weighing 5.57 grams. From this second ABW data, the ADG value could be obtained by subtracting ABW I by ABW II and then dividing by seven (time interval). The ADG (Average Daily Gained) values for each pond plot were A51 pond plots weighing 0.21, A52 pond plots weighing 0.26 grams, A61 pond plots weighing 0.18 grams. From the third sampling, the x 100% IOP Publishing doi:10.1088/1755-1315/1036/1/012121 3 ABW data obtained were A51 pond plots weighing 5.2 grams, A52 pond plots weighing 6.82 grams, A61 pond plots weighing 6.01 grams. Meanwhile, the ADG data that had been calculated were A51 pond plots weighing 0.07 grams, A52 pond plots weighing 0.17 grams, A61 pond plots weighing 0.06 grams. The fourth sampling was carried out so that the ABW data obtained were A51 pond plots weighing 6.47 grams, A52 pond plots weighing 9.25 grams, A61 pond plots weighing 8.11 grams. ADG data that had been calculated were A51 pond plots weighing 0.18 grams, A52 pond plots weighing 0.17 grams, A61 pond plots weighing 0.3 grams. The data could be seen in Figure 1.
This increase was due to the provision of sufficient frequency of feed. Feeding the right shrimp will increase the growth of shrimp [8]. The feeding was carried out four times a day at 07.00, 11.00, 16.00, and 20.00. Meanwhile close to harvest time, feeding five times a day was carried out at 07.00, 11.00, 14.00, 17.00, and 20.00. According to previous study, the influencing factors in feeding are the dose, time, and response of shrimp [9]. The amount of feed given to shrimp will continue to increase in line with the age of the shrimp. Meanwhile, the initial frequency of feeding was carried out 3 times a day until the final frequency (before harvest) was 5 times a day.

Figure 1. Data of shrimp absolute body weight in this study
The results obtained from vannamei shrimp culture are in Table 1. Shrimp size in aquaculture indicates the number of shrimp in 1 kg. Therefore, the lower the size of the shrimp, the higher the weight of the shrimp. Based on the yield data, the largest shrimp size was shrimp from the A52 pond plot and the largest FCR was also owned by the A52 pond plot. This was because the SR of the A52 pond plots was very low considering that the FCR was calculated by dividing   [10]. Good survival rate and FCR values are indicated because the nutritional content received by shrimp is sufficient. The feed used has a protein content of at least 36%. Protein is an important ingredient for the growth of shrimp [11]. The survival rate in A52 was low compared to other pools. The results of laboratory tests showed that the shrimp in A52 were infected with a disease called WSSV (White Spot Syndrome Virus). WSSV is a dangerous disease in shrimp that can cause death [12]. The water quality data could be seen in Table 2. The water quality of salinity and tempeature in the research ponds was not in accordance with the shrimp culture standards from the source used in this study.

Conclusion
It could be concluded the white snapper nursery in BBPBAP Jepara showed good results. The percentage of white snapper nursery in the form of seed survival rate at harvest was 80%, feed conversion ratio was 1.51. The average results of water quality parameters in white snapper fish rearing ponds included salinity ranging from 30-35 ppt, DO ranging from 3.2-3.8 mg/L, and water temperature ranging from 28.6-32.6 °C .