Archive for the ‘Perkuliahan’ Category

Keep Water for Poultry Clean to Avoid Serious Diseases

Senin, 9 Juni 2008 1 komentar

Since contaminated water can transmit serious diseases to birds, poultry owners should always provide good quality water for their flocks. “We know that avian influenza can be spread through water that wild ducks have been on,” says Gerald Hauer, assistant chief provincial veterinarian. “Most people know to keep their poultry away from dugouts and ponds, but we want to remind them to treat that water before they let their birds drink it.” To determine whether water needs treatment, first consider the source. If the water is from a well or municipal source, the risk of introducing diseases is minimal. If using surface water, such as from dugouts or ponds, the risk is much higher. Though there are several ways to treat water; chlorination is the most common and inexpensive. A concentration of two to five parts per million will kill most viruses, including avian influenza. Here are some formulas for mixing chlorine with water: * For a bulk tank, add 45 mL of household bleach (five-per-cent chlorine) to 455 litres of water. This is equivalent to adding 1.6 fluid ounces of five-per-cent bleach to 100 imperial gallons. * People treating water by the bucket can add 2.5 mL to 22.5 litres of water (half a teaspoon to a five-gallon pail). * If using an automatic water treatment system, be sure to set it to deliver the proper amount of chlorine. * Always let the water sit for 10 minutes with the chlorine added before giving it to the birds, (this is how long it might take for the chlorine to kill viruses present in the water). Sometimes water contains impurities that can affect the chlorine´s ability to kill viruses. For example, soil particles, organic material, ammonia and minerals can make chlorine ineffective. If there are high levels of any impurities, consult with a water quality specialist on ways to get around this problem. Poultry owners should be aware that changing watering practices can have unintended effects on flocks. “You want to pay attention to your birds´ consumption whenever you make a change in their water,” Hauer says. “You need to make sure they are drinking enough.” Also, even a small amount of chlorine can kill modified live virus vaccine added to the water. If vaccinating birds through the water, use clean water with no chlorine. The cardinal rule for birds is to keep them away from dirty water. “Never let poultry drink untreated water from a pond, dugout or anywhere else that wild birds have access to,” Hauer adds. “That is just basic biosecurity and it keeps all of Alberta´s livestock safe and healthy.” Published 06/06/2008 Source: Government of Alberta Agri-News


Avian Influenza Genome Sequences Released

Senin, 9 Juni 2008 Komentar dimatikan

The complete genetic coding sequences of 150 different avian influenza viruses were released today by U.S. Department of Agriculture (USDA) scientists and government, industry and university collaborators. The information improves scientific understanding of avian influenza, a virus that mainly infects birds but that can also infect humans. "This is a major milestone in avian influenza research," said David Suarez, research leader of the Exotic and Emerging Avian Viral Diseases Research Unit at the Southeast Poultry Research Laboratory (SEPRL) operated at Athens, Ga., by the Agricultural Research Service (ARS). ARS is the chief intramural scientific research agency of USDA. Suarez oversees the ARS avian influenza virus repository at SEPRL. "This sequence information, deciphered by our large team, will help researchers better understand virus biology and improve diagnostic tests for avian influenza viruses," Suarez added. Today’s release to GenBank, the National Institutes of Health’s genetic sequence database, was part of a special sequencing project supported by the presidential initiative on avian influenza. Partners involved in collecting the viruses included USDA’s Animal and Plant Health Inspection Service’s Wildlife Services, as well as researchers at the University of Georgia (UGA), Ohio State University (OSU) and the University of Alaska-Fairbanks, and others. After the virus isolates were prepared at SEPRL, the virus’ noninfectious genetic material, called ribonucleic acid or RNA, was sent to industry collaborator SeqWright Corporation in Houston, Texas, which used its expertise to fully sequence the genome of each virus. The sequence information was reviewed and annotated at SEPRL for release to GenBank. "The project’s ultimate goal is to sequence 900 avian influenza viruses from the SEPRL repository," said Suarez. "These include avian influenza viruses collected from both poultry and wild bird species in the United States and around the world." The sequence information will be combined with studies comparing the viruses’ ability to infect and cause disease in several poultry species including chickens, turkeys and domestic ducks. The analysis of the sequence and biological data will provide new insights into how these viruses cause disease in man and animals. The biological characterization was performed with collaborations with UGA, OSU and University of Delaware collaborators. Published 05/30/2008 Source: USDA Agricultural Research Service


Some avian flu H7 viruses growing more human-like

Senin, 9 Juni 2008 Komentar dimatikan

Scientists have found evidence that North American avian influenza viruses of the H7 subtype are becoming more like human flu viruses in their ability to attach to host cells, which suggests they may be improving their capacity to infect humans. The investigators determined that several recent North American H7 viruses have an increased ability to bind to a type of receptor molecule that is abundant on human tracheal cells and is less common in birds. Their results were published this week by the Proceedings of the National Academies of Science. The finding-which comes as the deadly Eurasian H5N1 virus continues to be seen as the likeliest candidate to spark a pandemic- "underscores the necessity for continued surveillance and study of these [North American H7] viruses as they continue to resemble viruses with pandemic potential," says the report. The study was done by scientists from the US Centers for disease Control and Prevention (CDC), Emory University in Atlanta, and the Scripps Research Institute in La Jolla, Calif. H7 viruses have caused a number of disease outbreaks in poultry in Europe and North America in recent years, though far fewer than the widespread outbreaks caused by the H5N1 virus. H7 viruses also have occasionally infected humans, typically causing only mild conjunctivitis. But a veterinarian died of an H7N7 infection during the devastating poultry outbreaks in the Netherlands in 2003. Previous research has established that avian flu viruses prefer to link up with cell receptor molecules known as alpha 2-3 glycans, whereas human flu viruses, such as H1N1 and H3N2, prefer to attach to receptors called alpha 2-6. The terms refer to the nature of the link between sialic acid (SA), which forms the tip of the receptor molecule, and galactose, an adjoining sugar unit.

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Vitamin K

Minggu, 25 Mei 2008 Komentar dimatikan

Nama vitamin K berasal dari koagulasi. Vitamin tersebut adalah esensial untuk pembentukan prothrombin oleh hati. Koagulasi darah terdiri dari dua tingkatan utama, yaitu: (1) prothrombin (dengan adanya thromboplastin, kalsium dan faktor-faktor lainnya) dirubah kedalam thrombin; dan (2) fibrinogen (dirangsang oleh trombin) dirubah kedalam gumpalan fibrin.

Karena prothrombin merupakan bagian penting dari mekanisme penggumpalan darah, maka defisiensi vitamin K menyebabkan waktu pembekuan darah diperpanjang sedemikian rupa sehingga anak ayam atau anak kalkun yang diserang dapat mati karena pendarahan akibat luka ringan. Untuk menjaga jangan sampai terjadi defisiensi vitamin K, pabrik-pabrik makanan ternak menambahkan senyawa vitamin K sintetik (menadion atau menadion natrium bisulfit) ke dalam ransumnya.

Vitamin K akan kehilangan aktivitasnya dengan adanya obat-obatan sulfa, yang merupakan antagenis terhadap vitamin K. Obat-obatan tersebut tidak mempunyai pengaruh bila vitamin K diberikan dalam bentuk menadion atau menadion natrium bisulfit.Racun jamur merupakan pula antagonis terhadap vitamin K. Vitamin K larut dalam lemak, stabil terhadap panas dan labil terhadap oksidasi alkali, asam kuat, cahaya dan penyinaran.

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Stabilitas Lemak Hewan dengan Antioksidan

Kamis, 15 Mei 2008 Komentar dimatikan

Semua lemak hewan yang akan digunakan dalam ransum perlu distabilisasi dengan antioksidan untuk menghindari terjadinya ketengikan dan nilai peroksida yang tinggi. Ketengikan pada lemak dan minyak ada dua macam, yaitu hidrolitik dan oksidatif. Ketengikan hidrolitik umumnya terjadi akibat bekerjanya mikroorganisme terhadap lemak atau minyak, sehingga menimbulkan hidrolisis sederhana dari lemak ke dalam asam lemak, digliserida, monogliserida dan gliserol. Lemak yang mengalami ketengikan hidrolitik, tidak akan terganggu nilai gizinya.

Ketengikan oksidatif atau peroksida lipida, menyebabkan penurunan dalam nilai energi lemak atau minyak. Pada peroksidasi lipida maka asam lemak tidak bebas mula-mula mengalami pengurangan hidrogen dan hal ini menimbulkan pembentukan radikal bebas di bagian yang tidak jenuh. Reaksi tersebut dikatalisir oleh zat-zat mineral mikro dengan adanya oksigen. Bila reaksi terjadi pada bahan makanan yang tidak mengandung vitamin E atau antioksidan lainnya, maka radikal bebas tersebut oleh oksigen atmosfer dengan cepat sekali dirubah menjadi asam lemak peroksida radikal bebas dan kemudian menjadi asam lemak hidroperoksida. Vitamin E, ethoksiquin atau antioksidan lainnya dapat menghalang-halangi terjadinya peroksida tersebut dengan menyediakan hidrogen kepada radikal bebas yang mula-mula terbentuk ke dalam asam lemak asal. Bila hidroperoksida dibiarkan terbentuk, maka hidroperoksida tersebut meneruskan penguraiannya dengan cara memecahkan ke dalam macam-macam aldehida dan keton.

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Bilangan Yodium pada Lemak

Rabu, 14 Mei 2008 Komentar dimatikan

Bilangan yodium adalah ukuran derajat ketidakjenuhan. Lemak yang tidak jenuh dengan mudah dapat bersatu dengan yodium (dua atom yodium ditambahkan pada setiap ikatan rangkap dalam lemak). Semakin banyak yodium yang digunakan semakin tinggi derajat ketidakjenuhan. Biasanya semakin tinggi titik cair semakin rendah kadar asam lemak tidak jenuh dan demikian pula derajat ketidakjenuhan (bilangan yodium) dari lemak bersangkutan. Asam lemak jenuh biasanya padat dan asam lemak tidak jenuh adalah cair; karenanya semakin tinggi bilangan yodium semakin tidak jenuh dan semakin lunak lemak tersebut.

Karena setiap ikatan kembar dalam asam lemak akan bersatu dengan dua atom yodium maka dapatlah ditentukan setiap kenaikan dalam jumlah ikatan rangkap (kemungkinan ketengikan) yang timbul pada waktu lemak tersebut mulai disimpan.

Pengetahuan mengenai bilangan yodium adalah penting untuk menentukan derajat dan jenis lemak yang akan digunakan dalam ransum. Sesungguhnya bilangan yodium suatu jenis lemak perlu ada dalam batas-batas tertentu. Untuk lemak sapi bilangan yodium harus ada dalam batasan 35 dan 42. Untuk lemak babi bilangan yodiumnya dapat bervariasi antara 52 dan 67.

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Stabilitas Vitamin A

Selasa, 13 Mei 2008 Komentar dimatikan

Vitamin A dan prekursornya tahan panas bila tidak ada oksigen atau zat-zat yang dapat menyebabkan oksidasi. Cara memasak yang biasa dilakukan tidak merusak vitamin A. Makanan yang dibekukan tetap mengandung kadar vitamin A, akan tetapi ketengikan minyak dan penyimpanan di udara terbuka atau cahaya akan merusak vitamin tersebut. Vitamin C (asam askorbat), asam sitrat dan vitamin E (tokoferol), sebagian dari senyawa-senyawa antioksidan yang banyak jumlahnya, dapat dibunakan untuk menjaga stabilitas vitamin A. Minyak hati ikan cod akan tahan berbulan-bulan bila disimpan dalam tempat yang tertutup dan bebas cahaya.

Leguminosa tertentu, terutama kacang kedele dan alfalfa mengandung suatu enzim lipoksigenase yang dengan cepat merusak karoten dan xantofil dan mungkin pula merusak vitamin A melalui serangkaian oksidasi dengan asam lemak tidak jenuh ganda. Pengeringan kacang kedele dan alfalfa, akan menghancurkan enzim tersebut.

Untuk menjamin cukup vitamin A dalam ransum unggas dan hewan ternak lainnya, maka produsen-produsen pelengkap vitamin A telah menciptakan suatu cara menstabilkan vitamin tersebut. Cara yang ditempuh ada dua macam: (1) cara mekanis, dengan membungkus butir-butir vitamin A dalam lemak, gelatin atau lilin sehingga berbentuk butir-butiran kecil yang mencegah sebagian besar vitamin A berhubungan langsung dengan oksigen, hingga vitamin tersebut dicerna dalam saluran pencernaan hewan; dan (2) dengan menggunakan zat antioksidan yang dengan nyata memperpanjang periode induksi dan dengan demikian mendahului oksidasi aktif dari vitamin A. Antioksidan utama yang digunakan secara luas adalah 6-ethoksi 1,2-dihidro-2, 2,4-trimethilquinoline (ethoksiquin).


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