Judul: The Status of DCAD Ration and It’s Relationship with Milk Production and Metabolic Disorders in Lactating Dairy Cows on Public Farms in Bogor.
Abstrak: Ketosis merupakan gangguan metabolik yang sering menyerang sapi perah laktasi dan berpotensi menurunkan produksi susu. Gangguan ini dapat dicegah dengan mengatur DCAD (Dietary Cation Anion Difference) ransum. Penelitian ini bertujuan mempelajari manajemen DCAD pada sapi laktasi yang dipelihara di wilayah Bogor (Kebon Pedes dan KUNAK) serta mengevaluasi hubungannya dengan produksi susu dan kejadian gangguan metabolisme dari 15 peternak di setiap wilayah. Hasil penelitian menunjukkan DCAD ransum 100% positif dengan kisaran wilayah Kebon Pedes 4,2, Ketosis is a metabolic disorder that often affects lactating dairy cows and can potentially reduce milk production. This disorder can be prevented by adjusting the DCAD (Dietary Cation Anion Difference) in the diet. This study aims to investigate DCAD management in lactating cows raised in the Bogor area (Kebon Pedes and KUNAK) and evaluate its relationship with milk production and the incidence of metabolic disorders among 15 farmers in each area. The study results showed that the DCAD in the diet was 100% positive, with the range for Kebon Pedes being 4.2±187.4 100 kg-1 DM and for KUNAK 54.52±217.06 100 kg-1 DM. A positive DCAD is necessary during the lactation period. Milk production in Kebon Pedes was 13.67 day-1 cow-1 , while in KUNAK, it was 15.87 day-1 cow-1 . The incidence of ketosis was observed in 13% of cows in Kebon Pedes and 6% in KUNAK. ANOVA analysis of both areas showed that livestock performance and production in KUNAK (landbase) were better than in Kebon Pedes (landless). Based on these findings, it can be concluded that DCAD management in KUNAK is better, thus feed management improvement is needed, especially in Kebon Pedes, to increase milk production and reduce metabolic disorders
Keyword: DCAD

Judul: Evaluation of the Dietary Cation-Anion Difference Profile of Pre-partum and Post-partum Cows Over the Cow's Performances in Koperasi Peternakan Bandung Selatan Pangalengan
Abstrak: Hipokalsemia merupakan salah satu gangguan metabolik yang umum terjadi pada sapi perah fase post-partum. Gangguan ini dapat dicegah dengan mengatur kandungan dietary cation-anion difference atau DCAD pada pakan. Dietary cation-anion difference perlu diperhatikan dari fase pre-partum sapi perah. Penelitian ini bertujuan untuk mengamati status DCAD pada masing-masing 15 sapi pre-partum dan post-partum di KPBS Pangalengan. Hasil penelitian menunjukkan DCAD sapi pre-partum bernilai -205,8±238,5 mEq/kg BK dan post-partum bernilai -164,34±175,38 mEq/kg BK. Sebanyak 86,67% sapi fase pre-partum sudah sesuai dengan kebutuhan DCAD bernilai negatif sedangkan hanya 18,75% sapi post-partum yang sudah sesuai dengan kebutuhan DCAD bernilai positif. Hasil uji korelasi menunjukkan adanya korelasi lemah antara DCAD dengan performa ternak berupa pH urin, gangguan metabolik, produksi susu, dan kualitas susu. Berdasarkan hal tersebut dapat disimpulkan bahwa manajemen DCAD sapi post-partum belum sesuai sehingga diperlukan penyesuaian terhadap pakan ternak dengan suplementasi atau reformulasi ransum., Hypocalcemia is one of the metabolic disorders that commonly occurs in dairy cows during the post-partum phase. This disorder can be prevented by regulating the dietary cation-anion difference profile in their diet. The dietary cation-anion difference profile needs to be managed from the pre-partum phase. This research aims to observe the DCAD profile in both 15 pre-partum and post-partum cows at KPBS Pangalengan. The research found that DCAD in pre-partum cows had a value of -205.8±238.5 mEq/kg DM and for the post-partum cows ware -164.34±175.38 mEq/kg DM. As many 86.67% of pre-partum cows had the appropriate negative DCAD values, while only 18.75% of post-partum cows has the appropriate positive DCAD values. Correlation tests showed a weak correlation between DCAD and the cow’s performances such as urine pH, metabolic disorder, milk production, and milk quality. Based on these, it can be concluded that DCAD management of the post-partum cows are not optimal, necessitating adjustments in cow’s feed through supplementation or diet reformulation.
Keyword: DCAD, hipokalsemia, performa ternak, post-partum, pre-partum, cow's performance, hypocalcemia

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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