Judul: Kualitas semen beku kambing peranakan etawah menggunakan modifikasi pengencer tris soya dan tris kuning telur
Abstrak: Reproduction of goats in Indonesia mostly managed by natural mating, while the Artificial Insemination (AI) has been limited. The success rate of AI in goats has been low because of some factors, one of those has been identified as the low quality of extender. Tris Egg Yolk (TEY) and AndroMed® have been widely used for extenders of frozen semen in goats. Effect of Tris Soya (TS) that have lesitin nabati and studies to describe the profiles of each extenders to the sperm quality have been quite limited. The aim of this study was to compare TEY, AndroMed® and TS extenders on sperm motility and viability before and after freezing of goats semen. Semen was collected from three sexually mature Etawah Crossbreed goats twice a week, each semen sample was divided into three tubes to be mixed with TEY, AndroMed® or TS before those got frozen. Sperm motility and viability were evaluated macroscopically before freezing and microscopically before and after freezing. The result of this study revealed that TEY and AndroMed® gave higher sperm motiliy (68.52±0.64% and 68.71±1.95%) than TS (37.03±4.25%). The viability of sperm was also higher in TEY and AndroMed® (73.45±1.52% and 73.94±1.31%) compared TS (46.76±4.76%). It was concluded that TEY and AndroMed® were better extenders to protect goats sperm compared TS.
Keyword: AndroMed®, Etawah Crossbreed, frozen semen, Tris Egg Yolk, Tris Soya.

Judul: Efektivitas penambahan a-tokoferol di dalam pengencer tris dan susu skim terhadap kualitas semen beku kambing peranakan etawah
Abstrak: Proses kriopreservasi menyebabkan penurunan kualitas semen setelah pencairan kembali karena faktor-faktor termal (cekaman dingin), mekanikal (kristal es intraseluler), kimiawi (komponen pengencer) dan stres osmotik (tekanan osmotik pengencer). Selain itu kematian spermatozoa dapat pula diakibatkan oleh pengaruh radikal bebas yang menimbulkan reaksi berantai peroksidasi lipid yang merusak membran sel spermatozoa. Reaksi berantai peroksidasi lipid dapat dicegah dengan menambahkan suatu antioksidan ke dalam pengencer semen yang dapat memutus reaksi tersebut., The objectives of this research were to determine the influence of extenders and effect of a-tocopherol as an antioxidant on frozen semen quality of crossbred Etawah bucks. Semen samples collected from eight crossbred Etawah bucks were extended with two different extenders (Tris and skim milk) supplemented with a-tocopherol with doses of 0.0, 0.2, 0.3 and 0.4 g. each in 100 ml of the extenders and packaged in ministraws of the Minitüb system. Extended liquid semen in Minitübes were equilibrated at 3-5°C for four hours and frozen over the liquid nitrogen vapor for 10 minutes and stored for 24 hour in liquid nitrogen (-196° C). The stored semen was then thawed at 37°C for 30 seconds.
Keyword: Frozen semen, Goat, Skim milk, Tokoferol

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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