In the fish aquaculture management, fish feed is identified as a major problem. The high cost and scarcity of fishmeal in formulated feeds have led to the use of other protein sources such as earthworms and animal by-product. Earthworm is an alternative protein source to replace the fish meal in the fish feed formulation. In this study, total nitrogen content in earthworm powder is determined using the Kjeldahl method by employing the statistical software, Full Factorial Design (FFD) which could provide the significant information about the studied parameters. The parameters are the digestion time (min) and the volume of sulfuric acid (H2SO4) (ml). From the analysis of variance (ANOVA), the volume of H2SO4and the interaction between digestion time and the volume of H2SO4arefound to be important parameters in the nitrogen determination process via the Kjeldahl method. The highest nitrogen content obtained was 12.23% when using 15 ml H2SO4 and 60 mins of digestion time. The value of R2 is 0.9986 which shows that the selected parameters (the digestion time and the volume of H2SO4) and its corresponding levels are highly correlated to the percentage nitrogen content in earthworm powder using the Kjeldahl method. ABSTRAK:Dalam pengurusan akuakultur ikan, makanan telah dikenalpasti sebagai masalah utama. Kos yang tinggi serta kekurangan sumber makanan telah menggalakkan pencarian sumber protein baru seperti cacing tanah dan hasil sampingan sembelihan haiwan ternakan. Cacing adalah sumber protein alternatif menggantikan ramuan ikan (fish meal) dalam formulasi makanan ikan. Dalam kajian ini, kandungan jumlah nitrogen dalam serbuk cacing tanah telah dianalisa menggunakan kaedah Kjeldahl dengan menggunapakai perisian statistikal iaitu Full Factorial Design (FFD) yang boleh memberikan maklumat yang penting berkenaan dengan parameter-parameter yang dikaji. Parameter-parameter tersebut adalah masa pencernaan (min) dan isipadu asid sulfurik (H2SO4) (ml). Daripada analisa varian (ANOVA), isipadu H2SO4 dan interaksi antara masa pencernaan dan isipadu H2SO4 telah dikenalpasti sebagai parameter-parameter utama dalam proses penentuan kandungan nitrogen melalui kaedah Kjeldahl. Kandungan nitrogen yang tertinggi diperolehi adalah 12.23% bila menggunakan 15 ml H2SO4 dan 60 minit masa pencernaan. Nilai R2 adalah 0.9986 menunjukkan bahawa parameter-parameter (masa pencernaan dan isipadu H2SO4) dan aras yang dipilih mempunyai perkaitan langsung yang tinggi dengan kandungan nitrogen dalam serbuk cacing dengan menggunakan kaedah Kjeldahl.KEYWORDS: nitrogen content;, earthworm; Kjeldahl method
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