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 lokal pada titik tetap non-hiperbolik
Abstrak: Bifurkasi menggambarkan perubahan pada struktur orbit di sekitar titik tetap. Titik tetap dibagi menjadi dua yaitu titik tetap hiperbolik dan titik tetap non-hiperbolik. Titik tetap non-hiperbolik terjadi jika ada nilai eigen dengan bagian real sama dengan nol. Kestabilan dari titik tetap dapat diketahui dari nilai eigen yang diperoleh dari pelinearan medan vektor. Pada bifurkasi satu-dimensi ditemukan kasus-kasus untuk bifurkasi saddle-node, bifurkasi transcritical dan bifurkasi pitchfork. Bifurkasi saddle-node terjadi jika satu sisi dari nilai parameter tidak terdapat titik tetap dan pada sisi lain terdapat dua titik tetap, dimana yang satu stabil dan yang lainnya tak-stabil. Bifurkasi transcritical terjadi jika terdapat pertukaran kestabilan, yaitu dari titik tetap stabil menjadi titik tetap tak-stabil dan sebaliknya. Sedangkan bifurkasi pitchfork dibagi menjadi dua, yaitu: bifurkasi pitchfork supercritical dan bifurkasi pitchfork subcritical. Bifurkasi pitchfork supercritical terjadi jika satu titik tetap stabil berubah menjadi dua titik tetap stabil dan satu titik tetap tak-stabil, dan bifurkasi pitchfork subcritical terjadi jika satu titik tetap stabil dan dua titik tetap tak-stabil berubah menjadi satu titik tetap tak-stabil. Bifurkasi Hopf (bifurkasi dua-dimensi) terjadi jika terdapat orbit periodik pada struktur orbitnya yang berupa lingkaran dengan jari-jari konstan. Ada atau tidaknya orbit periodik dapat diketahui setelah sistem ditransformasikan ke dalam koordinat polar. Orbit periodik ini dapat bersifat stabil maupun tak-stabil. Model periklanan (advertising) Feichtinger merupakan salah satu contoh penerapan bifurkasi Hopf Model ini menghasilkan satu titik tetap dan orbit periodik yang bersifat stabil.
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