Judul: Uji Kecernaan In vitro Silase Campuran Rumput Gajah (Pennisetum purpureum) dan Lamtoro Merah (Acacia villosa)
Abstrak: The aim of this experiment was to study in vitro digestibility of mixed Pennisetum purpureum and Acacia villosa silage in different proportion. The experiment used factorial block randomized design 3x6 with three replicates. Factor A was the ratio between P. purpureum and A. villosa i.e. A1 = 60% P. purpureum : 40% A. villosa, A2 = 50% P. purpureum : 50% A. villosa, and A3 = 40% P. purpureum and 60% A. villosa. Factor B was incubation times i.e. B1-B6 for 4, 8, 12, 24, 48, and 72 hours. Data were analyzed using analysis of variance (ANOVA), the difference between treatments were tested with polynomial and Duncan test. The result showed that bacterial population, and organic digestibility were influenced by treatments (P<0.05). Ammonia concentrations, and dry matter digestibility were influenced by incubation time (P<0.05). Protozoa populations was influenced by treatments and incubation time (P<0.05). Interaction between two factors was detected (P<0.05) on total VFA concentrations. Methane was reduced by the increased of A. villosa. It is concluded that the addition of 40% of A. villosa cause the highest digestibility and total VFA production but produce the highest methane.
Keyword: P. purpureum, methane, digestibility, A. villosa

Judul: Kualitas Fermentasi dan Kecernaan Silase Campuran Rumput Gajah (Pennisetum purpureum) dan Litter Broiler
Abstrak: Penelitian ini bertujuan mengevaluasi kualitas fermentasi dan kecernaan silase campuran berbahan rumput gajah dan penambahan litter broiler dengan tingkat persentase berbeda. Penelitian ini menggunakan rancangan acak lengkap dengan empat perlakuan dan empat pengulangan. Perlakuan tersebut terdiri dari LB0 = 100 % rumput gajah + 0 % litter broiler; LB10 = 90 % rumput gajah + 10 % litter broiler; LB25 = 75 % rumput gajah + 25 % litter broiler LB50 = 50 % rumput gajah + 50 % litter broiler. Parameter yang diujikan dalam penelitian ini adalah kualitas proksimat silase, konsentrasi amonia silase, nilai pH, nilai fleigh, dan kualitas pencernaan silase secara in vitro. Data dianalisis menggunakan ANOVA dan dilanjutkan dengan uji Tukey apabila terdapat hasil yang memiliki perbedaan signifikan (P<0,05). Hasil menunjukkan bahwa penambahan litter broiler dengan tingkat persentase berbeda secara signifikan mempengaruhi kualitas fermentasi dan kecernaan silase (P<0,05). Semakin tinggi penambahan litter maka semakin menurun kualitas fermentasi dan pencernaan silase., This study aimed to evaluate the fermentation and digestibility quality of mixed silage made from elephant grass and the addition of broiler litter with different percentage levels. This study used a complete randomized design with four treatments and four replications. The treatment consisted of LB0 = 100% elephant grass + 0% broiler litter; LB10 = 90% elephant grass + 10% broiler litter; LB25 = 75% elephant grass + 25% broiler litter; and LB50 = 50% elephant grass + 50% broiler litter. The parameters tested were the proximate quality of silage, silage ammonia content, pH value, fleigh value, and in vitro digestion quality of silage using the Tilley and Terry method. The data obtained was analyzed using Analysis of Variance (ANOVA) and continued with the Tukey test if there were results that had significant differences (P<0.05). The results showed that the addition of broiler litter with different percentage levels significantly affected the quality of fermentation and digestibility of silage (P<0.05). The higher addition of litter, the lower the quality of fermentation and digestion of silage.
Keyword: Silage, Nutrient Digestibility, Fermentation, Broiler Litter

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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