Judul: Effects of Implementation of Recirculating System on Survivability in Polyculture of Whiteleg Shrimp (Litopenaeus vannamei) with Nile Tilapia (Oreochromis niloticus)
Abstrak: Produktivitas budidaya udang vaname (Litopenaeus vannamei) dapat ditingkatkan dengan menerapkan budidaya polikultur udang vaname dengan ikan nila (Oreochromis niloticus) pada sistem resirkulasi. Penelitian bertujuan mengevaluasi pengaruh penggunaan ikan nila pada polikultur udang vaname, serta penerapan sistem resirkulasi dalam budidaya polikultur udang vaname dan ikan nila dengan rasio tebar udang vaname:ikan nila dan bobot awal yang berbeda. Penelitian dilakukan dengan metode studi pustaka. Penelitian dilakukan dengan cara menganalisis berbagai sumber pustaka berupa jurnal ilmiah terkait penerapan sistem resirkulasi pada polikultur udang vaname dan ikan nila. Penggunaan ikan nila dalam polikultur udang vaname dapat meningkatkan sintasan dan pertumbuhan udang vaname. Selain itu, penggunaan rasio tebar dan bobot awal yang tinggi pada sistem resirkulasi dapat menurunkan produktivitas budidaya polikultur udang vaname dan ikan nila., The productivity in whiteleg shrimp (Litopenaeus vannamei) culture can be increased by implementing the polyculture of whiteleg shrimp and Nile tilapia (Oreochromis niloticus) in a recirculating aquaculture system. This research aims to evaluate the effects of Nile tilapia usage in polyculture of whiteleg shrimp, and the implementation of recirculating aquaculture system in polyculture of whiteleg shrimp and Nile tilapia with different whiteleg shrimp:Nile tilapia ratio and initial weight. This research was conducted by literature study. This research was done by analyzing various literary sources such as scientific articles on implementation of recirculating system on polyculture of whiteleg shrimp and nile tilapia. The usage of Nile tilapia in polyculture with whiteleg shrimp increases the survivability and growth of whiteleg shrimp. Also, the usage of higher fish ratio and initial weight in recirculating aquaculture system may reduce the productivity of polyculture of whiteleg shrimp and Nile tilapia. Keyword: polyculture, recirculating aquaculture syst
Keyword: polyculture, recirculating aquaculture system, survivability

Judul: Production Performance of Whiteleg Shrimp  (Litopenaeus vannamei) Field Scale given Different Feed Additives
Abstrak: Salah satu upaya yang dapat dilakukan untuk meningkatkan fungsi pakan adalah dengan suplementasi bahan tambahan pakan (feed additive) yang memiliki berbagai fungsi baik dalam hal peningkatan kinerja pertumbuhan maupun kesehatan. Penelitian ini bertujuan mengevaluasi pengaruh penambahan feed additive yang berbeda terhadap performa pertumbuhan, gambaran darah, dan efisiensi biaya pakan udang vaname Litopenaeus vannamei yang dibudidayakan pada tambak intensif. Penelitian ini menggunakan dua perlakuan dengan tiga kali ulangan, yaitu feed additive 1 (FA1) dan feed additive 2 (FA2). Perlakuan FA1 merupakan perlakuan dengan penggunaan feed additive alternatif yang menggantikan semua feed additive yang digunakan pada perlakuan FA2. Penelitian ini dilakukan pada tambak intensif dengan luas kolam 2500 m2 dengan padat tebar 125 ekor/m2 selama 86 hari. Nilai total haemocyte count (THC) menunjukkan adanya perbedaan yang signifikan (p<0,05) antar kedua perlakuan. Nilai bobot akhir udang pada perlakuan FA1 dan FA2 adalah sebesar 21,65 g dan 20,85 g, dengan pertumbuhan spesifik masing-masing sebesar 9,07 %/hari dan 9,03 %/hari, serta rasio konversi pakan masing-masing sebesar 1,38 dan 1,42. Tingkat kelangsungan hidup perlakuan FA1 memiliki nilai 67,08% sedangkan perlakuan FA2 60,67%, dengan nilai produktivitas pada perlakuan FA1 sebesar 1,57 kg/m2 dan FA2 sebesar 1,33 kg/m2. Udang yang diberi pakan dengan suplementasi feed additive FA1 menunjukkan kinerja pertumbuhan yang tidak berbeda nyata dengan perlakuan FA2, namun dengan biaya feed additive dua kali lebih rendah. Berdasarkan hasil penelitian ini dapat disimpulkan bahwa aplikasi feed additive FA1 dapat diterapkan sebagai alternatif berbagai feed additive yang diberikan pada perlakuan FA2 pada skala lapangan budidaya udang vaname., One of the efforts that can be made to improve the function of feed is by supplementing feed additives which have various functions, both in terms of increasing growth and health performance. This study aims to evaluate the effect of adding different feed additives to growth performance, blood count, and feed cost efficiency of whiteleg shrimp Litopenaeus vannamei cultured in intensive ponds. This study used two treatments with three replications, namely feed additive 1 (FA1) and feed additive 2 (FA2). FA1 treatment is a treatment with the use of alternative feed additives that replace all feed additives used in FA2 treatment. This research was conducted in intensive ponds with a pond area of 2500 m2 with a stocking density of 125 fish/m2 for 86 days. The value of total haemocyte count (THC) showed a significant difference (p<0.05) between the two treatments. The final weight values of shrimp in FA1 and FA2 treatments were 21.65 g and 20.85 g, with specific growths of 9.07%/day and 9.03%/day, respectively, and feed conversion ratios of respectively. 1.38 and 1.42. The survival rate of FA1 treatment had a value of 67.08% while FA2 treatment was 60.67%, with a productivity value of 1.57 kg/m2 for FA1 treatment and 1.33 kg/m2 for FA2. Shrimp fed with FA1 feed additive supplementation showed growth performance that was not significantly different from FA2 treatment, but with twice the cost of the feed additive. Based on the results of this study, it can be concluded that the application of FA1 feed additives can be applied as an alternative to various feed additives given to the FA2
Keyword: Feed additive, growth, productivity, whiteleg shrimp

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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