Judul: Pengaruh Suplementasi Vitamin E dan Selenium dalam Ransum terhadap Performa Ayam Petelur Umur 46-51 Minggu
Abstrak: Indonesia as a tropical country with high ambient temperature and relatively humidity cause heat stress-related decreases in laying hen performance. Supplementation of antioxidants in the diet can reduce the negative effect of heat stress. This study was aimed to determine the effects of Vitamin E, and Selenium supplementation in the diets on the performances of Isa-Brown laying hens aged 46-51 weeks. Ninety six 46-weeks-old of laying hens were randomly assigned to 4 treatments, 4 replications of 6 birds each. The birds were fed either P1 = control diet or P2 = control diet supplemented with Selenium (0.8 ppm Se optimin), P3 = control diet supplemented with vitamin E (300 mg DL-α-tocopherol-acetate/kg diet), or P4 = control diet supplemented with combination of Vitamin E and Selenium (300 mg DL-α-tocopherol-acetate plus 0.8 mg Se optimin). Statistical analysis results showed that the treatments did not influence (P>0.05) the parameters observed. However, the result showed that combination of Vitamin E and Selenium supplementation tend to increase the egg weight and decrease the feed conversion.
Keyword: vitamin E, selenium, performance, laying hen, heat stress

Judul: Pengaruh Fortifikasi Vitamin E dan Zink dalam Ransum terhadap Performa Ayam Petelur.
Abstrak: Indonesia as a tropical country with high ambient temperature and relatively humidity cause heat stress-related decreases in laying hen performance. Enrichment of antioxidants in the diet can reduce the negative effect of heat stress. The purpose of this study was to determine the effects of fortification vitamin E, zinc organic, and its combination as antioxidants in commercial diets on the performance of ISA-Brown laying hens. This study used 160 laying hens aged 20-25 weeks. The experimental design used in this research was completely randomized design (CRD) with 4 treatments, 4 replications of 10 birds of each. The birds were fed either a control diet (R0) or a control diet fortified with vitamin E 200 ppm (R1), zinc organic 200 ppm (R2), or a combination of vitamin E 200 ppm and zinc organic 200 ppm (R3). The results showed that fortification of vitamin E and zinc organic or its combination increased hen day production, egg mass production and feed conversion. Feed consumption of hens fed with vitamin E and vitamin E plus zinc organic was higher (P<0.05) than that of the control. Egg weight remained similar in all treatments. Combination of fortification dietary vitamin E 200 ppm and zinc organic 200 ppm resulted the best performance of laying hen.
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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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