Judul: The use of hydrolyzed Azolla pinnata to substitute soybean meal in juvenile Nile tilapia (Oreochromis niloticus) diet
Abstrak: Nile tilapia, Oreochromis niloticus is one of the most cultured fish species in tropical and subtropical countries of the world. It provides one of the main sources of income and animal protein throughout the world. Because of their faster growth rate, tolerance to harsh environment and ease culture technique, tilapia offers the possibility of commercial and home-grown protein. However, feed is the key cost variable in tilapia culture, which accounts 80% of total production cost. The high feed cost is mostly caused by the high protein content in the diet and the high price of protein. Soybean is one of the most utilized plant protein sources in aquaculture feed. However due to its cost, availability and competitiveness with other human use, alternative plant protein sources were explored which is Azolla pinnata. Azolla pinnata is a cheap, sufficient nutritional value for protein lipid carbohydrate vitamin and mineral, locally available and affordable to most fish farmers. Nutritional quality of Azolla pinnata can be improved by fermentation methods or by hydrolysis using sheep rumen liquor. This contains protease, lipase, amylase, and cellulase enzymes. This study aimed to use hydrolyzed aquatic macrophyte Azolla pinnata meal to substitute soybean meal (SBM) in the diet of Nile tilapia (O.niloticus). Where, enhancement of nutritional composition of azolla pinnata, hydrolyzed Azolla pinnata digestibility and inclusion level of hydrolyzed Azolla pinnata in Nile tilapia diet for growth performance was evaluated. In the nutritional composition of the Azolla pinata meal after hydrolysis with rumen digestive fluid showed satisfactory increase of nutritional contents including protein content 34.03%, lipid 5.56%, and reduced crude fiber up to 7.80%. Morever chromic oxide at 0.5% was mixed as the diet inert markers. The fish feces were collected from six aquariums (50×40×30cm3) during 21 days. The reference diet showed high digestibility of dry matter, protein and energy including 88.1%, 92.8% and 91.2% respectively, for those of test diet with 34.1% 50.3% and 32.3% respectively for digestibility study. Concerning the growth study, five test diets of 30% crude protein were formulated by different substitution level of soybean meal by hydrolyzed Azolla pinnata meal including diets A, B, C, D, E (0%, 10%, 20%, 30% and 40% of hydrolyzed Azolla pinnata meal respectively). The experiment was conducted during 57 days where 10 fish of 8-10g were stocked in 15 aquariums (50×40×30cm3). Fish were fed two times daily to apparent satiation. At the end of this study, results showed that hydrolyzed Azolla pinnata meal can be added to Nile tilapia feed up to 30% without affecting fish growth performance.
Keyword: Digestibility, growth, hydrolyzed Azolla pinnata, Oreochromis niloticus

Judul: Evaluation of rubber seeds (Hevea brasilliensis) fermented meal using rumen liquour as a protein source in diet of nile tilapia (Oreochromis niloticus).
Abstrak: This research is aimed to investigate the effect of replacing soybean meal with rubber seed meal (RSM) as protein sources for feed of Nile tilapia (Orecochromis niloticus) strain Nirwana. The fish (8.14 ± 0.08 g) were cultured in rearing aquaria (100x50x50 cm3) connected to a recirculating aquaculture system, and fed three times daily with 5 different concentrations of RSM feeds: A (0% RSM), B (25% RSM), C (50% RSM), D (75% RSM) and E (100% RSM), with the same protein content and gross energy: 31% and 433.5 kcal GE g-1 respectively. The study consisted of two phase. Phase one aims to determine the digestibility of feed (14 days) and phase two study aimed to growth performance (50 days). During the feeding period, some parameters were measured including feeding rate, feed efficiency, protein retention, fat retention, daily growth rate, cholesterol, triglycerides, feed digestibility, LDL (low density lipoprotein), HDL (high density lipoprotein), hepatosomatic indeks (HSI), glycogen in heart and muscle, and lipid in hearth and muscle. Experimental design was set according to completely randomized design with 5 treatments and 4 repetitions of each. Data were statiscally analysed with one-way analysis of variance (ANOVA) using software Minitab version 16.0, with 95% (p<0.05) confidence interval. The results showed that the replacement of soybean meal with the rubber seed meal at 50% gave the highest protein digestibility (92.95%) and total feed digestibility (70.30%). On the contrary, increasing rate of the replacement up to 100% decreased both protein digestibility and total feed digestibility to 86.79% and 54.58%. Substitution up to 75% and 100% showed low blood protein to 3.57% and 2.58%. Other results revealed that the use of 75% and 100% lead to the increasing of cholesterol, triglyceride and LDL (low density lipoprotein), but decreased HDL (high density lipoprotein). Overall, the replacement of soybean meal with fermented rubber seed meal as protein sources showed no significant different in fish growth rate; 3.43% (25% RSM), 3.42% (50% RSM) and 3.41% (control). This research result may suggest that rubber seed meal which was previously fermented with rumen liquid can be used to replace soybean meal as protein sources and can be used up to 50% in diet of nile tilapia.
Keyword: Alternative protein source, Oreochromis niloticus, rubber seed meal HDL and LDL

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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