Judul: Mekanisme pengaturan proses laktasi pada sapi
Abstrak: Laktasi merupakan fase terakhir dari siklus reproduksi mammalia dimana didalamnya termasuk proses pembentukan dan pengeluaran air susu dari kelenjar mammae oleh suatu reflex neurohormonal. Kelenjar mammae merupakan kelenjar penghasil air susu, pada sapi terdiri dari empat buah kelenjar mammae yang ma- sing-masing disebut kuartir. Perkembangan kelenjar mammae dirangsang oleh hormon-hormon ovarium, pertumbuhan saluran dipelihara oleh estrogen dan pertumbuhan lobulialveoler oleh progesteron. Hormon-hormon yang terlibat dalam kontrol proses laktasi adalah Prolactin, Oxytocin, Cortison, ACTH, Insulin, Thyroxin, Vasopressin dan Epinephrin. Unsur utama yang terkandung dalam air susu yaitu protein, lemak, laktosa, mineral dan vitamin. Pembentukan air susu terjadi dalam sel epithel alveoli kelenjar mammae dan terjadi diantara dua masa pemerahan. Air susu dibentuk dari konstituen-konstituen darah, dimana mineral dan vitamin diserap langsung dari darah sedangkan protein, laktosa dan lemak disintesa dalam kelenjar mammae. ...
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Judul: Gambaran kadar lemak air susu pada periode awal laktasi ( Studi Kasus )
Abstrak: Air susu dihasilkan oleh kelenjar susu hewan betina dalam periode laktasi. Unsur penting yang dikandung dalam air susu adalah protein, lemak, laktosa, mineral dan vitamin. Jumlah produksi dan komponen air susu yang dihasilkan tidak selamanya konstan, sebab keadaan ini dipengaruhi oleh bebe- rapa faktor seperti bangsa, umur, iklim, makanan dan tata laksana peternakan. Periode laktasi dibagi menjadi tiga periode yaitu periode awal laktasi termasuk periode kolos trum, periode sekresi normal dan periode akhir laktasi. Penelitian ini bertujuan untuk mengetahui gambaran ka- dar lemak air susu pada periode awal laktasi. Diharapkan studi kasus ini dapat memberi gambaran mengenai perubahan kadar lemak air susu selama periode awal laktasi. Sampel air susu didapat dari seekor sapi perah produktif di peternakan Gunungbatu, Bogor. Untuk menguji kadar lemak dalam sampel air susu awal laktasi digunakan metode Gerber. Dari hasil pengujian ka dar lemak didapatkan pada hari pertama laktasi kadar lemak tinggi, kemudian menurun tajam. Selanjutnya kadar lemak susu sangat berfluktuasi dan lebih rendah jika dibandingkan dengan kadar lemak dalam Kodeks Susu. Rendahnya kadar le- mak susu di daerah tropis kemungkinan disebabkan rendahnya nilai gizi hijauan (serat kasar yang diberikan) yang meru- pakan ransum utama bagi sapi perah…
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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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