0, 22, 24, 26, 28, 30, 32, and 34 Fermentasi Rhizopus sp. menyebabkan perubahan kimia dan fisika pada substrat, termasuk daya apung dan stabilitas dalam air. Sifat ini bisa dimanfaatkan untuk membuat pakan ikan apung secara biologis. Dalam penelitian ini, ragi tempe digunakan sebagai agen hayati dalam fermentasi pakan ikan tenggelam komersial dimana periode fermentasi divariasi selama 0, 22, 24, 26, 28, 30, 32, dan 34 jam. Pakan fermentasi yang dihasilkan dikeringkan dengan oven, selanjutnya kualitas fisiknya diukur dan dibandingkan dengan pakan ikan apung komersial (kontrol positif). Hasil penelitian menunjukkan bahwa pakan fermentasi memiliki stabilitas dalam air, daya serap air, dan daya apung yang lebih baik dibandingkan dengan pakan tenggelam komersial. Namun nilai ini masih lebih rendah dibandingkan pakan apung komersial. Oleh karenanya, proses fermentasi menggunakan ragi tempe memiliki potensi untuk diperbaiki lebih lanjut sebagai metode biologis pembuatan pakan ikan apung.Kata Kunci: daya apung, daya serap air, fermentasi, Rhizopus sp., stabilitas dalam air

To reduce the feed production cost of floating fish feed, an innovative method which is cheaper, easier, and simpler compared to the use of extruder machine is needed to provide buoyancy to fish feed. This research was conducted to determine the physical characteristics of floating fish feed prepared through fermention using Rhizopus oryzae on the mixed substrate consisting of commercial sinking fish feed, cassava bagasse, and Lemna minor. The resulting fermented feed was subsequently compared with commercial sinking fish feed in terms of its water stability, absorption, and floatability. The water stability curves of both feed types showed a similar pattern for 20 hours. Both decreased dramatically in the first 0.5 hours, from 100% to 81% for the fermented feed, and to 83% for the commercial feed. The shape of a 40-minute water absorption curve for both feed types was very similar. The fermented feed absorbed water nearly 4 times its initial dry weight, while commercial feed up to about twice as much as its initial dry weight. For three hours, both fermented and commercial floating pellets stayed afloat 100% without sinking. Thus, fermentation using R. oryzae deserves further development as an alternative way to provide buoyancy to fish feed. ABSTRAKUntuk menekan biaya produksi pakan ikan apung, diperlukan inovasi pengapungan pakan ikan yang lebih murah, mudah, dan sederhana dibandingkan dengan penggunaan mesin ekstruder. Penelitian ini dilakukan untuk mengetahui karakteristik fisik pakan apung hasil fermentasi menggunakan kapang Rhizopus oryzae pada substrat campuran pakan tenggelam komersial, onggok, dan Lemna minor. Pakan fermentasi ini lalu dibandingkan dengan pakan apung komersial dalam hal stabilitas dalam air, absorbsi air, dan daya apung. Stabilitas dalam air kedua jenis pakan memiliki pola yang mirip selama 20 jam. Stabilitas keduanya menurun drastis pada 0,5 jam pertama, dari 100% ke 81% untuk pakan apung fermentasi, dan ke 83% untuk pakan apung komersial. Bentuk kurva absorpsi air selama 40 menit untuk kedua jenis pakan sangatlah mirip. Pakan apung fermentasi menyerap air hampir 4 kali bobot kering awalnya, sedangkan pakan apung komersial hingga sekitar 2 kali bobot kering awalnya. Selama tiga jam, baik pakan apung fermentasi maupun komersial mengapung 100% tanpa tenggelam. Jadi, fermentasi menggunakan R. oryzae layak dikembangkan lebih lanjut sebagai cara pengapungan alternatif pakan ikan.Kata Kunci: daya apung, daya serap air, stabilitas dalam air, pakan apung, pakan tenggelam

Impact of Slicing and Moulding Techniques on the Floatability of the Fish Feed Fermented by Rhizopus sp.ABSTRACTThe use of Rhizopus sp. mycelium as biocoating, biostabilizing, and biofloating agent in the production of floating fish feed through solid fermentation had already been studied as a much simpler alternative to mechanical extrusion. The fermented fish feed, however, had poor floatability in aerated water, probably due to structural damage during the size reduction process of the feed. Thus, this study used alternative size-reducing methods, namely slicing and moulding, to improve the floatability of the fermented feed. Other physical characteristics were also measured and compared to those of commercial sinking and floating fish feeds. Results showed that both the moulded and the sliced fermented-feeds had lower density as well as higher water stability, absorption capacity, floatability, and durability compared to those of the commercial sinking feed used as the fermentation substrate. The hydrophobicity of all the feeds tested were similar, however. The floatability of the fermented feeds obtained in this study was much higher than those of the previous studies. Keywords: floatability, floating feed, sinking feed, water absorption, water stabilityABSTRAKPenggunaan miselium Rhizopus sp. sebagai pelapis permukaan, penstabil, dan pengapung hayati dalam pembuatan pakan ikan apung melalui fermentasi padat telah diteliti sebagai alternatif yang jauh lebih sederhana dibandingkan dengan metode ekstrusi mesin. Namun, pakan ikan fermentasi ini memiliki daya apung yang buruk dalam air bergelembung udara, yang mungkin disebabkan kerusakan struktural selama proses pengecilan ukuran pakan. Karenanya, penelitian ini menggunakan metode lain untuk mengecilkan ukuran, yakni pencetakan dan pengirisan, dalam rangka meningkatkan daya apung pakan yang difermentasi. Karakteristik fisik lainnya juga diukur dan dibandingkan dengan pakan ikan tenggelam dan terapung komersial. Hasil menunjukkan bahwa proses fermentasi serta metode pengecilan dimensi yang digunakan menghasilkan pakan yang memiliki massa jenis lebih rendah, serta stabilitas air, daya serap air, daya apung, serta ketahanan benturan lebih tinggi dibandingkan dengan pakan tenggelam komersial yang digunakan sebagai substrat fermentasi. Namun, nilai hidrofobisitas semua pakan yang diuji adalah sama. Daya apung pakan fermentasi dalam penelitian ini jauh lebih tinggi daripada penelitian sebelumnya.Kata Kunci: daya apung, daya serap air, stabilitas dalam air, pakan apung, pakan tenggelam

Sinking pellets disintegrates easily in water, hence reducing water quality and fish productivity due to oxygen-consuming biodegradation of the unconsumed feed. Modifying sinking pellets into more stable floating pellets using an edible tempeh mould through solid fermentation has previously been studied as an alternative to the more expensive extrusion method. However, the fermentation resulted in the uncontrolled growth of the fungal mycelium, causing the individual pellets to aggregate into a single compact mass. The fermentation also contributed to the dry weight loss of the initial pellets. Thus, using a laboratory-scale bioreactor, this study aimed at generating water-stable and floating properties on sinking-pellets through sub-optimal fermentation using tempeh mould. The conditions varied were the amount of sinking pellets substrate, fermentation duration, and aeration-humidification. Results showed that less pellet aggregation was observed with shorter fermentation time. Based on 40-minute laboratory tests in water, the best 80% floating ability was achieved for 10 g sinking pellets fermented for 72 h with humidified bubble aeration. The fermented pellets showed 42% water stability and 4.86% dry weight loss.

To reduce broiler production cost, a study was carried out on utilisation of alternative, less costly feed components, namely kepok banana peel and corn hominy which were mixed and fermented using the fungus Rhizopus oryzae. The fermented substrate was added into commercial feed in order to determine its influence on the poultry’s production performance. This study employed a completely randomized design (CRD) with four treatments: one using 100% pure commercial feed, and the other three commercial feed mixed with the fermented feed component at the levels of 5%, 10% and 15%. All treatments were repeated four times during 25 days growth period. The results showed that supplementation of the fermented ingredient in the broiler ration at the levels of 5%, 10%, or 15% had no significant effect (P>0,05) on the feed consumption, body weight gain, feed conversion ratio, and the final body weight of the animals. Although mixing the fermented feed ingredient up to 15% in the commercial feed promoted the growth of the broilers, the results were not yet comparable to pure commercial feed.Keywords: Corn hominy, broiler, fermentation, kepok banana peel, Rhizopus oryzae AbstrakUntuk mengurangi biaya produksi ayam pedaging, dilakukan pengkajian penggunaan bahan penyusun pakan alternatif yang lebih murah, yaitu kulit pisang kepok dan ampok jagung yang dicampur dan difermentasi menggunakan jamur Rhizopus oryzae. Hasil fermentasi tersebut lalu ditambahkan pada pakan komersial ayam pedaging dengan tujuan mengetahui pengaruhnya terhadap penampilan produksi ayam pedaging. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) dengan empat perlakuan, yaitu satu perlakuan 100% pakan komersial murni, dan tiga perlakuan pakan komersial yang dicampur bahan pakan hasil fermentasi tersebut dengan kadar 5%, 10%, dan 15%. Seluruh perlakukan diulang empat kali selama 25 hari masa pemeliharaan. Hasil penelitian menunjukkan bahwa penambahan bahan pakan terfermentasi ke dalam ransum ayam pedaging pada kadar 5%, 10%, atau 15% tidak memberikan pengaruh nyata (P>0,05) terhadap konsumsi pakan, pertambahan bobot badan, nilai koversi pakan, dan bobot badan akhir hewan. Meskipun penambahan bahan pakan fermentasi tersebut hingga 15% dalam pakan komersial mendukung pertumbuhan ayam pedaging, namun capaian pertumbuhannya belumlah sebaik pakan komersial.Kata kunci: Ampok jagung, ayam pedaging, fermentasi, kulit pisang kepok, Rhizopus oryzae