Judul: Utilization Tannin Chesnut (Castenia sp.) as a Protective Agent in Slow Release Nitrogen
Abstrak: Penggunaan urea sebagai penyumbang suplemen pakan utama karena memiliki harga yang murah, mudah dalam pengaplikasian, dan bermanfaat sebagai sumber nitrogen untuk sintesis protein mikroba. Urea memiliki kelemahan salah satunya dapat terhidrolisis cepat menjadi amonia. Solusi dari permasalahan tersebut maka dilakukan mekanisme yang dikenal dengan nitrogen lepas lambat menggunakan tanin jenis terhidrolisis. Penelitian ini bertujuan untuk mengevaluasi rumen in vitro terhadap perlindungan urea dengan menggunakan tanin komersil chestnut dalam berbagai taraf antara lain 0% (P0), 1% (P1), 2% (P2), 3% (P3) ke dalam pakan kontrol. Data dianalisis menggunakan analysis of variance dan perbedaan nyata antar perlakuan dilakukan uji tukey’s hsd test. Hasil penelitian menunjukkan tidak ada perbedaan statistik pada pH rumen, kecernaan bahan kering (KcBK), kecernaan bahan organik (KcBO), dan sintesis protein mikroba (SPM). slow release nitrogen (SRN) berbeda nyata (P<0,05) pada volatile fatty acid (VFA) total. Efek perlindungan berpengaruh negatif terhadap VFA total seiring dengan peningkatan taraf SRN. SRN berbeda sangat nyata (P<0,01) pada produksi amonia. Efek perlindungan berpengaruh negatif terhadap produksi amonia seiring dengan peningkatan taraf SRN. Kata kunci: nitrogen lepas lambat, tanin terhidrolisis, in vitro ABSTRACT FEGGIE. Utilization Tannin Chesnut (Castenia sp.) as a Protective Agent in Slow Release Nitrogen. Supervised by ANURAGA JAYANEGARA and KOMANG GEDE WIRYAWAN. Urea has become indispensable for supplying the necessary feed supplement because of cheap, easy to use, and had a benefit as nitrogen sources for microbial protein synthesis. Urea have a weakness to readly hydrolyzable into amonia. For the solution with use the mechanism that we called slow release nitrogen with hydrolyzable tannin. This experiment was conducted to evaluate in vitro rumen on different levels of tannin chestnut such as 0% (T0), 1% (T1), 2%(T2), 3%(T3) into a control diet. Data were analysed using analysis of variance and any significant different further tested using tukey’s honest significant difference Test. Results this experiment showed addition of different concentration of tannin chestnut as urea protector did not affect with any parameters in pH rumen, dry matter digestibility, organic matter digestibility, and microbial protein synthesis. However, the addition of different concentration of tannin chestnut have negative effects on volatile fatty acid (VFA) total production (P<0,05) and amonia production (P<0,01). Keywords: hydrolyzable tannin, in vitro, slow relase nitrogen
Keyword: hydrolyzable tannin, in vitro, slow release nitrogen

Judul: Fermentability and Digestibility of Feed Added Slow Relase Urea-Nitrate In Vitro.
Abstrak: Penelitian ini bertujuan menguji pengaruh penambahan slow release urea-nitrat dalam ransum secara in vitro. Penelitian ini menggunakan rancangan acak kelompok 5 perlakuan dan 4 ulangan. Perlakuan terdiri dari P0 = ransum kontrol; P1 = P0 + urea; P2 = P0 + urea-nitrat; P3 = P0 + urea-nitrat dilapisi dengan molases; P4 = urea-nitrat dilapisi dengan limbah cair sari kurma. Peubah yang diamati adalah kecernaan bahan kering (KcBK), kecernaan bahan organik (KcBO), konsentrasi amonia (NH3), derajat keasaman (pH), volatile fatty acid (VFA) total, sintesis protein mikroba (SPM), total produksi gas, dan gas metan. Data dianalisis menggunakan analysis of variance (ANOVA) dan perlakuan yang berbeda nyata akan dilakukan uji lanjut dengan uji duncan menggunakan statistical product and service solutions (SPSS) 25. Hasil penelitian menunjukkan bahwa perlakuan tidak berpengaruh nyata (P>0,05) terhadap nilai KcBK, KcBO, VFA total, pH, SPM, total produksi gas, dan gas metan. Perlakuan yang berpengaruh nyata (P<0,05) adalah konsentrasi amonia (NH3). Simpulan penelitian ini adalah penambahan slow release urea-nitrat belum mampu menurunkan konsentasi amonia., This study aimed to examine the effect of the addition slow release urea-nitrate in rations in vitro. This study used a randomized block design with 5 treatments and 4 replications. The treatment consisted of P0 = control ration; P1 = P0 + Urea; P2 = P0 + urea-nitrate; P3 = P0 + urea-nitrate coated with molasses; P4 = urea-nitrate coated with palm juice liquid waste. The observed variables were dry matter digestibility (KcBK), organic matter digestibility (KcBO), ammonia concentration (NH3), degree of acidity (pH), total volatile fatty acid (VFA), microbial protein synthesis (SPM), total gas production, and methane gas. Data were analyzed using analysis of variance (ANOVA) and significantly different treatments would be further tested with Duncan's test using statistical product and service solutions (SPSS) 25. The results showed that the treatment had no significant effect (P>0.05) on the KcBK, KcBO, total VFA, pH, SPM, total gas production, and methane gas. The treatment that had a significant effect (P<0.05) was the concentration of ammonia (NH3). The conclusion of this study was the addition of slow release urea-nitrate has not been able to reduce the concentration of ammonia.
Keyword: ammonia concentration, in vitro, methane gas, slow release urea-nitrate

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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