Judul: Study of feedlot optimality through manipulation of feed, compensatory growth and fattening time period
Abstrak: Usaha penggemukan sapi (Feedlot) di Indonesia pada dekade 10 tahun terakhir ini menunjukkan perkembangan yang pesat. tetapi d~ika ekonomi mak:ro yang tidak menentu akibat krisis ekonomi yang berkepanjangan saat ini, telah menimbulkan implikasi terhadap situasi yang tidak menguntungkan bagi usaha penggemukan sapi (Feedlot) schingga salah satu altematif untuk mengatasi masalah tersebut adalah mencari suatu model penggemukan sapi yang efisien. sehingga usaha penggemukan sapi dapat memberikan keuntungan yang optimal. Model penggemukan sapi yang dikcmbangkan adalah melalui manipulasi terhadap komponen yang memiliki kontribusi dominan terbadap biaya produksi dan berdampak tcrhadap peningkatan kualitas produk daging. Manipulasi dilakukan terhadap kualitas pakan, p.e-n-c-ra-p-a-n- f-c-n-om--e-na pertumbuhan kompensasi dan penentuan periode waktu pcnggemukan yang efisicn, schingga tujuan dari penelitian ini adalah ( 1) untuk mengetahui pengaruh perbedaan kualitas pakan (perbedaan kadar protein/energi), pertumbuhan kompensasi dan periode waktu penggemukan (2. 3 dan 4 bulan) terhadap kinerja pertumbuhan. produksi pemotongan (karkas dan daging) dan kualitas daging (2) untuk mencari model penggemukan sapi yang optimal, dengan cara memanipulasi pakan. Pertumbuhan kompensasi dan penentuan periode waktu penggemukan sapi dalam kombinasi perlakuan yang sinergis., The objectives of the study was to find an optimum production of fattening model through manipulation of feed, compensatory growth and fattening period. One hundred eight young catties (steers) of Australian Commercial Cross (ACC), 2-3 years old were used and 54 heads of catties were slaughtered. Those catties were devided into 3 treated groups. Group I : was treated with different ration of Crude Protein (CP)/Metaboliz.able Energy (ME)= 16,12% /2534 kcal (T); 13,52% /2392 kcal (S) and 11, l 8% /2287 kcal (R) of l kg dry matter ration. Group II : was treated with different condition of steers of thin body I compensatory growth (K) and not thin body/ non compensatory growth (NK). Average Daily Gain (ADG) ofK was more than 0,9 kg/day and NK was less than 0,9 kg/day. Group m : was treated with 3 different fattening time period of 2 months (WP 2); 3 months (WP3) and 4 months (WP4). The study was carried out on November 1997 to September 1998 at P. T. Kariyana Gita Utama f~ Cicurug, Sukabumi, West Java. P.T. Sampico Adhi Abbattoir, Tambun Bekasi, Balai Penelitian Ternak Ciawi, Bogor, Animal Product Technology Laboratory, Faculty of Animal Science and Faculty of Agriculture Technology Gadjah Mada University, Yogyakarta. Results showed that compensatory growth (K). fucreased Average Daily Gain, Feed efficiency, slaughtered weight, percentage of marbling, and unsaturated fatty acid. Different quality of ration (T, Sand R) did not indicated differences on ~owth performance and slaughtered yields. Time periods of fattening (WP 2, WP 3, WP 4) increased on slaughtered weight, dressing percentage, fat of carcass, percentage of marbling, tenderness of meat and unsaturated fatty acid. Optimum production of feedlot was reached at time period of fattening with compensatory growth and feed formulation was base upon consumption of CP and ME that adjusted to the nutrition requirement and considered to capital sirculation, preference of consumer and market.
Keyword: Feedlot, Feed, Compensatory growth, Fattening

Judul: Optimization of Beef Cattle Feed Composition at PT Firma Agros Terra Sukabumi Regency
Abstrak: Jumlah penduduk Indonesia saat ini meningkat diikuti dengan perbaikan tingkat pendapatan dan selera konsumen. Keadaan tersebut membuat konsumen saat ini cenderung memilih protein yang berasal dari hewan, salah satunya adalah daging sapi. Permintaan daging sapi yang tinggi belum dapat dipenuhi oleh pasokan atau produksi dalam negeri, sehingga pemerintah perlu melakukan impor. Produksi daging sapi yang masih rendah antara lain disebabkan pemberian pakan yang belum tepat. Sumber pakan di Indonesia yang beranekaragam dapat meningkatkan produksi daging sapi melalui optimasi komposisi pakan. Penelitian ini membahas penentuan komposisi pakan yang memenuhi kebutuhan nutrisi sapi pedaging pada tingkat biaya minimum. Analisis model program linear menunjukkan bahwa komposisi pakan terbaik untuk pembesaran sapi 450 kg adalah 13,59 kg jerami padi basah, 11,61 kg rumput gajah, 3,32 kg tepung jagung, dan 10,18 kg ampas tahu basah. Komposisi pakan tersebut menghasilkan tingkat biaya yang lebih rendah sebesar 27,71 persen dengan tetap memenuhi kebutuhan minimal 13,50 kg untuk BK, 1,41 kg untuk PK, dan 8,35 kg untuk TDN. Komposisi pakan terbaik untuk pembesaran sapi 350 kg adalah diperoleh 10,58 kg jerami padi basah, 9,01 kg rumput gajah, 2,59 kg tepung jagung, dan 7,92 kg ampas tahu basah. Komposisi pakan tersebut menghasilkan tingkat biaya yang lebih rendah sebesar 39,04 persen dengan tetap memenuhi kebutuhan minimal 10,50 kg untuk BK, 1,09 kg untuk PK, serta 6,54 kg untuk TDN., Indonesia's population is currently increasing followed by improvements in income levels and consumer tastes. This condition makes consumers today tend to choose proteins derived from animals, one of which is beef. High demand for beef has not been met by domestic supply or production, so the government needs to import. Low beef production is due, among others, to improper feeding. Diverse feed sources in Indonesia can increase beef production through optimization of feed compositions. This research discusses determination of feed composition for rearing cow weighing 450 kg was 13,59 kg of wet rice straw, 11,61 kg of elephant grass, 3,32 kg of corn flour, and 10,18 of wet tofu dregs. The results showed that the optimal or best combination of feed for a cow weight of 450 kg can save the cost of broiler feed by 27,71 persen . This good feed combination already meets the nutritional needs of dry ingredients (13,50 kg BK), meets the minimum needs of coarse protein (1,41 kg PK), and meets the total digestible nutrient (8,35 kg TDN) for livestock. Composition for rearing cow weighing 350 kg was 10,58 kg of wet rice straw, 9,01 kg of elephant grass, 2,59 kg of corn flour, and 7,92 of wet tofu dregs. The results showed that the optimal or best combination of feed for a cow weight of 350 kg can save the cost of cow feed by 39,04 persen. This good feed combination already meets the nutritional needs of dry ingredients (10,50 kg BK), meets the minimum needs of coarse protein (1,09 kg PK), and meets the total digestible nutrient (6,54 kg TDN) for livestock.
Keyword: Biaya minimum, komposisi pakan, kebutuhan nutrisi, sapi pedaging, program linier

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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