Judul: Berbagai jenis vaksin marek pada ayam
Abstrak: Penyakit Marek merupakan penyakit menular pada ayam yang disebabkan oleh virus herpes (DNA) ditandai dengan in filtrasi sel-sel neoplasma, pleomorf dan limfosit pada sya raf dan organ tubuh lainnya. Penyakit ini cukup menimbulkan kerugian pada peternak ayam di seluruh dunia termasuk Indonesia, untuk itu usaha pencegahan terhadap penyakit ini terus dilakukan. Vaksinasi merupakan suatu cara yang efektif untuk pencegahan penyakit Marek. dianggap paling Vaksinasi biasa- nya dilakukan di peternakan ayam pembibit diberikan pada ayam umur 1 hari. Vaksin Marek ada 4 macam yaitu: Vaksin HVT, atenuasi, avirulen dan polivalen yang merupakan cam- puran dari ketiga jenis vaksin tersebut. Kelemahan vaksin HVT, atenuasi dan avirulen adalah ku rang atau tidak efektif terhadap beberapa galur virus Marek di alam selain dipengaruhi oleh maternal antibodi dari HVT atau yang homolog. Ternyata kelemahan-kelemahan seper ti ini tidak berlaku bagi vaksin polivalen. Oleh Witter (1982) dinyatakan bahwa vaksin polivalen paling efektif di bandingkan dengan vaksin Marek tunggal. Vaksin polivalen belum dipasarkan secara meluas dan masih merupakan barang baru. Diharapkan kehadiran vaksin polivalen ini dapat menggantikan vaksin HVT yang biasa digunakan di lapangan….
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Judul: Kagagalan Vaksinasi Marek Pada Ayam
Abstrak: Vaksinasi Marek adalah suatu tindakan pencegahan paling efektif yang mutlak dilaksanakan terutama di peternakan ayam pembibit yaitu pada anak ayam umur 1 (satu) hari baik petelur maupun pedaging. Namun usaha vaksinasi ini tidak selamanya berhasil dengan memuaskan, kegagalan kadang- kadang masih ditemukan. Jenis vaksin Marek yang digunakan adalah vaksin HVT (herpes virus of turkey), vaksin atenuasi, vaksin avirulen serta vaksin polivalen (trivalen dan bivalen). Vaksin HVT, atenuasi dan avirulen masing-masing mempunyai kelemahan yaitu tidak efektif terhadap beberapa galur virus MD virulen di alam di samping adanya pengaruh dari maternal antibodi HVT maupun yang homolog. Sedangkan vaksin polivalen walaupun mempunyai spektrum lebih luas. terhadap virus-virus MD tetapi masih dipengaruhi oleh maternal antibodi HVT. Immunitas vaksin tidak mencegah superinfeksi virus MD virulen tapi hanya menurunkan tingkat viraemia cellassociated. Anak ayam yang di infeksi penyakit Gumboro terutama pada masa embryo atau umur anak ayam 1 (satu) hari antara lain bertanggung jawab atas kegagalan vaksinasi.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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