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: Pengaruh Suplementasi Berbagai Antioksidan Terhadap Performa dan Status Fisiologis Ayam Broiler yang Diberi Cekaman Terhadap Lingkungan Temperatur Tinggi
Abstrak: High ambient temperature results in heat stress on broiler chickens. Antioxidant is the most efficient suplement, which alleviate the negative effects of heat stress. This study was conducted to determine the effects of antioxidants suplementation on performance and physiological status of broiler chickens exposed to high environmental temperature. Ten days-old 48 broilers were randomly assigned to a 2x3 factorial design to 3 environmental treatments, 2 experimental diets of 8 replication of one birds each. The chickens were fed a commercial diet with or without mixed antioxidants. The environmental treatments were as follows: constant temperature at 25 ˚C, cyclic temperature at 25-35-25 ˚C, and constant temperature at 32 ˚C. Chickens in high environmental temperature had lower (P<0.01) feed intake, body weight, and body weight gain than in normal temperature. Antioxidants suplementation had no effect on performances and physiological. Antioxidants suplementation increased yellowness (P<0.05) of breast muscle. Antioxidants and environmental treatments did not influence malondialdehyde (MDA) level. These results suggested that antioxidants did not alleviate the negative effect of heat stress on broiler chickens.
Keyword: heat stress, broiler, antioxidants

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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