Judul: Evaluation of Acacia Tannin Extract Addition to Silage on Nutrient Content and Fermentative Characteristics of Silage
Abstrak: Silase dari hijauan tinggi protein memiliki kelemahan yaitu terjadinya deaminasi asam amino yang menghasilkan amonia. Penelitian ini bertujuan mengevaluasi penggunaan ekstrak tanin dari kulit kayu dan daun akasia sebagai aditif silase. Penelitian int menggunakan rancangan acak lengkap (RAL) faktorial yang terdiri atas 3 faktor (2 x 3 x 4) dengan 5 ulangan. Faktor A adalah penambahan inokulum bakteri asam laktat (Lactiplantibacillus plantarum); faktor B adalah sumber ekstrak tanin dari kulit kayu dan daun Acacia mangium; dan faktor C adalah jenis hijauan (Pennisetum purpureum, Indigofera zollingeriana, Gliricidia sepium, dan Stylosanthes guianensis). Data dianalisis menggunakan ANOVA dan apabila berbeda nyata diuji lanjut menggunakan uji Duncan. Parameter yang diamati, yaitu kualitas fisik, kandungan nutrien, pH, kandungan asam laktat, dan N-NH3 silase. Penambahan inokulum bakteri asam laktat berpengaruh nyata (p<0,05) terhadap kualitas, total asam laktat, dan konsentrasi N-NH3 silase. Pengaruh jenis tanin daun akasia menunjukkan hasil terbaik pada silase indigofera terhadap kualitas fisik, kandungan nutrien silase, dan asam laktat, namun belum optimal menurunkan konsentrasi N-NH3 silase. Kombinasi penambahan inokulum BAL dan jenis tanin daun akasia pada silase indigofera memberikan hasil terbaik terhadap kualitas fisik, kandungan nutrien, nilai pH, dan kandungan asam laktat silase., Silage from high-protein forage has the disadvantage of deaminating amino acids, which produces ammonia. This research aims to evaluate the use of tannin extract from acacia bark and leaves as a silage additive. This research used a factorial completely randomized plan consisting of 3 factors (2×3×4) with 5 replications. Factor A is the addition of lactic acid bacteria (Lactiplantibacillus plantarum) inoculum; factor B is a source of tannin extract from the bark and leaves of Acacia mangium; and factor C is the type of forage (Pennisetum purpureum, Indigofera zollingeriana, Gliricidia sepium, and Stylosanthes guianensis). Data were analyzed using ANOVA, and if significantly different were tested further using Duncan's test. The parameters analyzed were physical quality, nutrient content, pH, total lactic acid, and N-NH3 concentration of the silage. The addition of lactic acid bacteria inoculum had a significant effect (p<0.05) on the quality, total lactic acid, and N-NH3 concentration of the silage. The impact of the type of acacia leaf tannin showed the best results in Indigofera silage on physical quality, silage nutritional content, and total lactic acid, but did not optimally reduce the N-NH3 concentration of silase. The combination of adding LAB inoculum and acacia leaf tannins to Indigofera silage gave the best results on the physical quality, nutritional content, pH value, and lactic acid content of the silage.
Keyword: akasia, tanin, amonia, silase

Judul: Level of Addition of Lactic Acid  Bacteria to Rice Straw Silage and Oil Palm Frond Silage Resulted from Fiber  Cracking Technology
Abstrak: Penelitian ini bertujuan untuk mengidentifikasi pengaruh level pemberian bakteri asam laktat dengan taraf 0%, 0,1%, 0,3% dan 0,5% pada silase jerami padi dan silase pelepah sawit yang telah diolah melalui proses fiber cracking technology (FCT). Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) factorial dengan 2 faktor A (perbedaan hijauan), 4 faktor B (taraf penambahan BAL) dan 4 ulangan. Peubah yang diamati adalah parameter pH, konsentrasi amonia (NH3), volatile Fatty Acid (VFA), kecernaan Bahan Kering (KCBK), kecernaan bahan organik (KCBO). Data kecernaan in vitro dianalisis menggunakan analysis of variance (ANOVA) dan dilanjutkan dengan uji Duncan, Sedangkan parameter kualitas silase dan komposisi kimia bahan silase menggunakan analisis deskriptif. Hasil penelitian menunjukkan bahwa faktor penggunaan bahan jerami padi dan pelepah sawit memiliki pengaruh terhadap parameter kualitas silase, komposisi kimia dan kecernaan in vitro. Sedangkan faktor penambahan BAL hanya berpengaruh terhadap nilai konsentrasi VFA total., This study aimed to identify the level of effect from lactic acid bacteria at 0%, 0.1%, 0.3% and 0.5% on rice straw silage and oil palm frond silage which had been processed through the fiber cracking technology (FCT) process. This study used a factorial Completely Randomized Design (CRD) with 2 factors A (forage differences), 4 factors B (level of addition of LAB) and 4 replications. The observed variables were pH parameters, ammonia concentration (NH3), volatile Fatty Acid (VFA), dry matter digestibility and organic matter digestibility. In vitro digestibility data were analyzed using analysis of variance (ANOVA) and continued with Duncan's test, while the silage quality and chemical composition parameters used descriptive analysis. The results showed that the factor of using rice straw and palm fronds had an influence on the parameters of silage quality, chemical composition and digestibility in vitro. While the addition of LAB only affects the value of the total VFA concentration.
Keyword: fiber cracking technology, lactic acid bacteria, oil palm frond, rice  straw, silage

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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