Judul: Growth performance and antioxidants of red tilapia (Oreochromis sp.) fed  with citral addition
Abstrak: Citral merupakan salah satu bahan aktif yang terkandung dalam berbagai bahan alami seperti serai dan kulit jeruk. Citral berpotensi untuk digunakan sebagai fitoadditive pada pakan untuk meningkatkan kinerja pertumbuhan melalui peningkatan pemanfaatan karbohidrat pakan dan antioksidan pada ikan nila merah. Penelitian ini bertujuan mengevaluasi pengaruh penambahan citral pada pakan terhadap kinerja pertumbuhan dan aktivitas antioksidasi pada juvenil ikan nila merah (Oreochromis sp.). Penelitian ini menggunakan lima perlakuan pakan dengan tingkat penambahan citral yang berbeda dengan empat ulangan. Dosis citral yang digunakan yaitu 0 mg/kg (kontrol), 25 mg/kg, 50 mg/kg, 75 mg/kg, dan 100 mg/kg pakan. Ikan nila yang digunakan berukuran 1,21 ± 0,02 g sebanyak 15 ekor yang dipelihara dalam akuarium 0,8 × 0,4 × 0,35 m3 selama 60 hari. Ikan diberi pakan secara at-satiation dengan frekuensi pemberian pakan tiga kali sehari. Hasil penelitian ini menunjukkan bahwa perlakuan penambahan fitoadditive citral pada pakan tidak berpengaruh pada biomassa akhir (252-286 g), bobot individu akhir (19,82-22,05 g), tingkat kelangsungan hidup (85- 93 %), rasio efisiensi protein (2,66-3,15), aktivitas antioksidasi (114-119 U/ g protein) dan rasio konversi pakan (1,20-1,15) pada ikan nila merah. Berdasarkan hasil tersebut maka dapat disimpulkan bahwa penambahan citral pada pakan sebanyak 25 - 100 mg/kg pakan tidak berpengaruh nyata terhadap kinerja pertumbuhan, pemanfaatan pakan dan aktivitas antioksidan pada juvenil ikan nila merah., Citral is one of the active ingredients contained in various natural ingredients such as lemongrass and orange peel. Citral has the potential to be used as a phytoadditive in feed to improve growth performance by increasing the utilization of feed carbohydrates and antioxidants in red tilapia. This study aims to evaluate the effect of adding citral to feed on the growth performance and anti-oxidation activity of red tilapia (Oreochromis sp.). This study used five dietary treatments with different levels of citral with four replicates. Citral doses used were 0 mg/kg (control), 25 mg/kg, 50 mg/kg, 75 mg/kg, and 100 mg/kg of feed. 15 tilapia fish measuring 1,21 ± 0,02 g were reared in an aquarium of 0,8 × 0,4 × 0,35 m3 for 60 days. Fish were fed at satiation with a frequency of three times a day. The results of this study indicated that the addition of phytoadditive citral had no effect on final biomass (252-286 g), final mean body weight (19,82-22,05 g), survival (85-93 %), protein efficiency ratio (2,66-3,15), antioxidant activity (114-119 U/g protein) and feed conversion ratio (1,20-1,15) in red tilapia. Based on these results, it can be concluded that the addition of citral to feed as much as 25-100 mg/kg of feed has no significant effect on growth performance, feed utilization and antioxidant activity in red tilapia.
Keyword: antioxidation, citral, growth, red tilapia

Judul: Growth Performance of Tilapia Oreochromis sp. Fed with Citral Addition by Coating Method
Abstrak: Citral merupakan senyawa bioaktif feed additive yang dapat meningkatkan pemanfaatan karbohidrat. Feed additive yang ditambahkan pada pakan dengan metode coating diduga akan berbeda dengan yang dicampurkan pada saat pembuatan pakan karena adanya risiko leaching. Penelitian ini bertujuan mengevaluasi pengaruh penambahan citral pada pakan secara coating dengan dosis yang berbeda terhadap kinerja pertumbuhan dan antioksidan ikan nila Oreochromis sp.. Penelitian terdiri atas empat perlakuan yaitu pakan tanpa tambahan citral (C0) sebagai kontrol negatif, pakan dengan dosis citral 100 mg kg-1 menggunakan metode repelleting (CR100) sebagai kontrol positif, serta pakan dengan dosis citral berbeda menggunakan metode coating yaitu 150 mg kg-1 (CC150), 200 mg kg-1 (CC200) dan 250 mg kg-1 (CC250). Ikan nila dengan bobot awal 1,96, Citral is a bioactive feed additive compound that can improve carbohydrate utilization. Feed additives added to feed by coating method are expected to be different from those mixed during feed preparation due to the risk of leaching. This study aimed to evaluate the effect of adding citral to feed by coating with different doses on the growth and antioxidant performance of Oreochromis sp. tilapia. The study consisted of four treatments, namely feed without added citral (C0) as a negative control, feed with a dose of citral 100 mg kg-1 by repelleting method (CR100) as a positive control, and feed with different doses of citral by coating method, namely 150 mg kg-1 (CC150), 200 mg kg-1 (CC200) and 250 mg kg-1 (CC250). Tilapia with an initial weight of 1.96±0.00 g were reared in aquariums measuring 50 x 50 x 40 cm at a density of 15 fish per aquarium (200 fish/m3) for 60 days. The test feed was given with a frequency of three times a day at 08.00, 12.00 and 16.00 WIB at satiation. The results showed that the growth performance of tilapia given citral with both repelleting methods was better than feed without citral and with coating method. The CR100 positive control treatment produced the highest final biomass (Bt), final individual weight (Wt), specific growth rate (LPS), total feed consumption (JKP), protein efficiency ratio (REP), and protein retention (RP) and the lowest feed conversion ratio (RKP) than the citral treatment with the coating method at higher dose. The activity of superoxide dismutase (SOD) enzyme in CR100 treatment also showed higher results than other treatments. Based on the results of this study, it can be concluded that tilapia with citral by repelleting method at a dose of 100 mg kg-1 feed (CR100) produced the best growth performance and SOD activity compared to the coating method at higher doses.
Keyword: growth, tilapia, citral, coating, superoxide dismutase

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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