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: Pengaruh Taraf Inklusi Leguminosa Acacia villosa dan Aditif Lactobacillus plantarum 1A-2 serta Dedak Padi terhadap Kualitas Silase Gabungan Rumput–Leguminosa.
Abstrak: Ensiling of Napier grass (Pennisetum purpureum) combined with potential legume (Acacia villosa) aimed to evaluate the silage quality. Experiment consisted of two factors. First, the level of legume inclusion (0, 30, 40, 50, 60, and 70 % fresh weight) and second, the use of additives (control, 5% rice bran, 1% Lactobacillus plantarum 1A-2 inoculant, and combination rice bran and inoculant) were arranged in completely randomized block design of factorial treatment with three replicates. Crude protein and phenolic compound increased gradually following higher inclusion of legume. While crude fiber showed different result, higher inclusion implicated to lower fiber content (P<0.01). pH increased (P<0.01) to 4.30–4.75 by inclusion of leguminosae. Lactic acid bacteria population was lowest on legume inclusion up to 60%. Lactic acid concentration went down by inclusion of leguminosae more than 50%. Interaction between two factors was detected (P<0.01) on losses during ensiling.
Keyword: silage., rice bran, napier grass, Lactobacillus plantarum 1A-2, Acacia villosa

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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