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: Utilization of hydrolized duckweed (Lemna minor) meal as a soybean replacement in Nile tilapia (Oreochromis niloticus) diet,
Abstrak: Tilapia is a fast growing fish widely cultured in many tropical and sub tropical countries. The recent production figures reported our global production estimates for 2015 is 5,576.8 metric tons. In developing countries the major challenges facing aquaculture industry is high cost of production associated with fish feeds. Feed represents 40-70% of operating costs for aquaculture operations, increasing expenses and potential declining supplies soybean meal have led scientists to search for less expensive but compatible alternative protein sources for fish feed; most of which are based on animal or plant protein sources. The objectives of study was to determine the incubation period for hydrolysis of duckweed and to evaluate the use of hydrolized duckweed as aprotein source for the growth performance of Nile tilapia Three experiments were conducted to determine the composition and digestibility of hydrolyzed duckweed meal by sheep rumen liquor as the replacement of soybean meal in the diet of Nile tilapia. The first trial examined the effectivity of sheep rumen liquor enzyme to decrease crude fiber contents of (DWM), the added volume of sheep rumen liquor was 100 ml/kg DWM and then it was incubated for 0, 12, 24 hr . The second trial was to evaluate the apparent digestibility of hydrolyzed DWM for Nile Tilapia, apparent digestibility were determined using chromic oxide indicator added to both reference diet and test diets. The feed ingredients used in the trial were hydrolyzed DWM (HDWM) and unhydrolyzed DWM (DWM). Ten fish with an average weight of 18±0.36g were used in the trial and reared in the aquarium of size 30×40×50cm for 15 days; feces were collected from three replicates using a fecal collection column attached to the aquarium. Third trial was to evaluate the growth performance of Tilapia fed test diet with hydrolyzed Duckweed meal (HDWM). The experimental design was set according to completely randomized design with four treatments and three replicates of HDWM inclusion levels that is 0%, 15%, 30% and 45%. Nile tilapia fish with initial body weight of 18±0.36g was kept in 12 units aquarium size of 30×40×50cm at stocking density of 10fish/aquarium, the fish were fed two times a day at 08:00am and 16:00pm to apparent satiation for a period of 60 days. The results indicated that duckweed meal (DWM) hydrolyzed with 100 mL/kg and incubated for 24 hrs showed the lowest crude fiber contents of 13.68% compared to other treatments. Total digestibility of hydrolyzed duckweed (HDWM) meal was 87.3% compared with unhydrolyzed duckweed (DWM) which was 66.8%. Total final weight (TFW), survival rate (SR), specific growth rate (SGR), feed conversional rate (FCR) and protein retention (PR) shows growth performance at 15% inclusion. The results of this study showed that 100mL/kg sheep rumen liquor at incubation period of 24 hr can be suitable for hydrolysis of duckweed to reduce crude fiber also hydrolyzed duckweed can substitute soybean meal at an incubation rate of 15% in the diet of Nile tilapia and had the same growth and FCR with control diet
Keyword: Digestibility, Duckweed meal, Growth performance, Sheep rumen

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.
Keyword: