Eight European marine and freshwater crustaceans were experimentally infected with diluted shrimp haemolymph infected with white spot syndrome virus (WSSV). Clinical signs of infection and mortalities of the animals were routinely recorded. Diagnosis was by direct transmission electron microscopy (TEM), DNA hybridization (dot‐blot and in situ hybridization) using WSSV probes and by PCR using WSSV specific primers. High mortality rates were noted between 7 to 21 days post‐infection for Liocarcinus depurator, Liocarcinus puber, Cancer pagurus, Astacus leptodactylus, Orconectes limosus, Palaemon adspersus and Scyllarus arctus. Mortality reached 100%, 1 week post‐infection in P. adspersus. When infection was successful, direct TEM observation of haemolymph revealed characteristic viral particles of WSSV, some observed as complete virions (enveloped), others as nucleocapsids associated with envelope debris. WSSV probes showed strong positive reactions in dot‐blots and by in situ hybridization in sections and specific virus DNA fragments were amplified successfully with WSSV primers. White spot syndrome virus was pathogenic for the majority of the crustaceans tested. This underlines the epizootic potential of this virus in European crustaceans.

ABSTRAKPenelitian bertujuan untuk mengevaluasi penampilan produksi ayam petelur yang diberi pakan dengan sumber kalsium berbeda. Penelitian menggunakan 200 ekor ayam petelur strain Isa Brown umur 25 minggu. Ayam dipelihara didalam kandang batre individual selama 12 minggu. Empat sumber kalsium (batu kapur sebagai kontrol, 5% batu kapur + 2,5% limbah kerabang telur, 2,5% batu kapur + 5% limbah kerabang telur, dan 7,5% limbah kerabang telur) digunakan dalam pakan penelitian. Rancangan pecobaan yang digunakan yaitu Rancangan Acak Lengkap dengan 4 perlakuan dan 5 ulangan. Setiap unit percobaan terdiri dari 10 ekor ayam petelur. Parameter yang diukur yaitu konsumsi pakan, konsumsi protein, konsumsi kalsium, konsumsi fosfor, produksi telur, berat telur dan konversi pakan. Hasil penelitian menunjukkan bahwa penggunaan 7,5% limbah kerabang telur sebagai sumber kalsium meningkatkan konsumsi pakan, konsumsi kalsium, konsumsi fosfor, produksi telur dan berat telur kecuali konversi pakan. Kesimpulan dari penelitian ini adalah penggunaan limbah kerabang telur sebagai sumber kalsium pakan ayam petelur menghasilkan performa produksi lebih baik dibanding menggunakan batu kapur dan campuran batu kapur dengan limbah kerabang telur.Kata kunci : kalsium, limbah kerabang telur, penampilan, produksi. ABSTRACTThe research was aimed to evaluate the performance of laying hens fed different calcium sources. Two hundreds of Isa Brown laying hens were used in this study. The hens were raised in individual battery cages units for 12 weeks. Four calcium source (limestone as a control, 5% limestone + 2.5% eggshells waste, 2.5% limestone + 5% eggshells waste and 7.5% eggshell waste) were used in feed experiment. A completely randomized design was applied, with 4 treatments and 5 replications. Each experimental unit consisted of 10 laying hens. The parameters measured were feed intake, protein intake, calcium intake, phosphorus intake, egg production, egg weight and feed conversion ratio. Results of the research showed that the calcium source had significantly effect on performance productions. The use of eggshell waste 7.5% significantly increased the feed intake, calcium intake, phosphorus intake, egg production and egg weight except for feed conversion ratio. The conclusion of this research was that the use of eggshell waste as calcium source of feed resulted in better performance than using limestone or mixed limestone with eggshell waste.