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: Aplikasi Berbagai Dosis Bakteri Proteolitik L1k dalam Pakan untuk Pengendalian Streptococcosis pada Ikan Nila Oreochromis niloticus dengan Metode Kohabitasi
Abstrak: Tilapia is a popular freshwater commodity were attacked bacterial disease such as streptococcosis caused by Streptococcus agalactiae. The objective of this research are to assay added treatment of bacterial proteolytic L1k toward increase immune response immune of tilapia (Oreochromis niloticus) infected by Streptococcus agalactiae N14G with cohabitation method. In this study, fish were fed diets containing different doses of proteolytic bacteria of L1k with the doses of 1%, 2% and 3%. Control fish (positive control and a negative control) were not given feed containing probiotic. After that, the fish tested challenged by cohabitation method. Treatment of bacteria proteolytic L1k in different doses of 1%, 2% and 3% can increase the survival rate of tilapia (respectively for 93.33%, 95.56%, and 97.78%) compared with the positive control fish by 68.89%. The addition of bacteria proteolytic L1k as probiotics to the diet may increase the immune response
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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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