Judul: Seleksi bakteri proteolitik dan aplikasi enzim protease untuk meningkatkan kualitas pakan dan kinerja pertumbuhan ikan nila
Abstrak: Growth performance of fish is highly influenced by the quality of feed, which is determined dominantly by the quality of feedstuff used and also by supplementation of exogenous enzymes. This study aimed to select protease producing bacteria, to optimize their existing potential in producing protease and to evaluate the effect of dietary supplementation of bacterial protease on feed quality and growth performance of nile tilapia. Ten strains were isolated from gastrointestinal tract of Clarias gariepinus and two of them were selected based on their maximum clear zone diameter on casein agar medium and the absence of pathogenic activity against the test fish. The incubation time for maximum protease production of two strains was 72 hours, and the optimum dosage of bacterial protease was 1000 ml /kg feed, which was determined based on the level of hydrolyzed protein. A feeding study was conducted using 7 treatments with 3 replicate groups of nile tilapia (average weight of 4,07 ± 0.25 g), reared under laboratory condition. Result showed that the addition of A1 and L1 bacterial protease gave a significant increase on feed comsumption, growth rate of nile tilapia, apparent digestibility of dry matter and crude protein, protein retention and efficiency in formulated feed. Fish survival was not different among the seven treatments. This result suggested that bacterial protease was effective in improving feed quality and growth performance of nile tilapia when it was added to formulated feed containing poorly digestible feedstuffs.
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Judul: Application of Probiotics from Different Genera to Improve Growth Performance and Health Status of Tilapia Oreochromis niloticus Fry
Abstrak: Sejalan dengan perkembangan usaha budidaya ikan nila, terdapat beberapa masalah yang dihadapi pembudidaya salah satunya penyakit infeksius. Penyakit infeksius dapat mengganggu sistem metabolisme, memengaruhi pertumbuhan bahkan kematian massal. Penggunaan probiotik dapat menjadi alternatif untuk mencegah penyakit infeksius. Penelitian ini bertujuan menganalisis aplikasi probiotik dengan genus berbeda, yaitu S. lentus L1k dan B. cereus BR2 melalui pakan dalam meningkatkan kinerja pertumbuhan dan status kesehatan benih ikan nila. Ikan uji yang digunakan adalah ikan nila dengan panjang 5,22±0,33 cm dan bobot 2,23±0,10 g. Ikan dipelihara selama 42 hari dan diberi pakan suplementasi dengan pemberian pakan tiga kali sehari secara at satiation. Penelitian ini menggunakan rancangan acak lengkap (RAL) dengan 4 perlakuan dan 3 ulangan yang terdiri dari K (kontrol), S (S. lentus 106 CFU mL-1 ), B (B. cereus BR2 106 CFU mL-1 ), SB (S. lentus L1k 106 CFU mL-1 + B. cereus BR2 106 CFU mL-1 ). Hasil penelitian menunjukkan bahwa ikan nila yang diberi probiotik monospesies S. lentus L1k dan B. cereus BR2, serta kombinasi keduanya mampu meningkatkan kinerja pertumbuhan dan status kesehatan benih ikan nila. Hasil penambahan probiotik monospesies S. lentus L1k dan B. cereus BR2 tidak memberikan efek berbeda dengan penambahan probiotik dual-spesies S. lentus L1k dan B. cereus BR2.
Keyword: Bacillus cereus BR2, blood, enzyme, enzyme, Oreochromis niloticus, Staphylococcus lentus L1k

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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