Judul: Suplementasi Selenium Dan Vitamin E Terhadap Kandungan Mda, Gsh-Px Plasma Darah Dan Bobot Organ Limfoid Ayam Broiler Yang Diberi Cekaman Panas
Abstrak: High environmental temperatures may cause heat stress in poultry. High temperatures contributes to oxidative stress, a condition where oxidant activity (free radical) exceeds antioxidant activity. In this research, selenium and vitamin E were utilized as anti heat-stress agents for heat stress broilers. The research used 465 unsex broilers and they were divided into 2 conditions, comfort zone (25.22±0.05 oC) and high temperatures (29.80±0.76 oC). Variables measured were malondialdehyde (MDA), glutathione peroxidase (GSH-Px) in blood plasma and weight of lymphoid organ (bursa fabricius and tymus). The data collected were analyzed with a factorial completely randomized design of 3x3 (3 levels of vitamin E, 3 levels of selenium and 3 replication) and continued with Duncan test. The result showed that selenium and vitamin E supplementation was significantly decreased on MDA (p<0.05) and GSHPx (p<0.01) in blood plasma of heat stressed broilers, but it did not effect the weight of bursa fabricius and thymus of broilers. It could be concluded that the combination vitamin E (200 or 100 ppm) and selenium (0.3 ppm) is the most effective as anti heat-stress agent in broilers.
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Judul: The Expression of Heat Shock Protein 70 and Glutathione Peroxidase Gene with Selenium Supplementation and Its Effect on Productivity of Broiler in Tropical Environment.
Abstrak: Indonesia is a tropical country with an average temperature of 23 °C - 33 °C and humidity of 45-97% (BMKG 2012). The temperature and humidity have an impact on performance of broiler chickens. Heat stress is triggered by changes in ambient temperature. Heat stress can affect the productivity of broiler chickens. The newest strains of broiler chickens are the result of intensive selection with rapid growth ability which must be maintained at comfortable temperature. New possibilites for improving the performance of broiler production through the application of nutrigenomics approach to optimize the use of broiler chickens nutrients. Generally, nutrigenomic covers the nutrient development with affects expression of genes thus nutrigenomics of broiler should focusing on optimizing feed for broiler productivity. Selenium is an trace mineral which has antioxidant effect. Supplementation of organic selenium in broiler ration related with its antioxidant activity could reduce the effect of heat stress. The purpose of this experiment was to study the supplementation of selenium on expression of heat shock protein 70 (HSP70) and glutathione peroxidase (GPX) gene, glutathione peroxidase (GSH- Px) enzyme activity, malondialdehyde (MDA) and productivity (feed intake, body weight, body weight gain, feed conversion ratio and mortality) of broiler in tropical environment. The experiment was conducted using completely randomized designs with three treatments and four replications. The treatments in this experiment were: comfortable environment pens (25.0 oC-27.9 oC) using air conditioner without supplementation of selenium (AC), tropical environment pens (24.6 oC-32.9 oC) without supplementation of selenium (NS), and tropical environment pens (24.6 oC-32.9 oC) with supplementation of 0.30 ppm selenium (organic selenium (Optimin®SeY, Nutreco)) (PS). Each of treatment consisted of 40 day old chicks (DOC) strain Cobb (unsex). Parameters observed were HSP70 and GPX gene expression, GSH-Px enzyme activity, MDA and the productivities. The results showed that supplementation of organic selenium significantly increased (P<0.05) feed intake, body weight, body weight gain, and feed conversion ratio. By contrast, the expression of HSP70 and GPX gene, GSH-Px enzyme activity and MDA of broiler significantly decreased (P<0.05) in the tropical pens with organic selenium supplementation compared to the treatment without organic selenium supplementation. It is concluded that supplementation of 0.30 ppm organic selenium in broiler ration in tropical environment improved modulating the expression of HSP70 and GPX gene, and showed similar performance to broiler which kept in the comfortable environment without organic selenium supplementation by reduces oxidative stress in broiler which kept in tropical environment.
Keyword: broiler, GPX gene, HSP70 gene, selenium, tropical environment

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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