Kinerja perkembangan gonad bulubabi tripneustes gratilla yang diberi pakan buatan dengan kadar protein dan rasio energi protein berbeda serta hormon estradiol -17β

Abstract

Sea urchin is one of the important marine biota which has economic value. Its gonads fetch high price in many countries. The research was conducted in four phases. The first phase was to study the biological reproduction aspect of sea urchin (Tripneustes gratilla) that catched from Kupang Bay. Ten to thirty individuals were catched every month from May until December 2008. Parameters observed consisted of gonad weight, gonad somatic index, oocyte diameter, gonad colour, test diameter, and body weigth. The second phase was to study gonad development of sea urchin that reared in captivity. Twenty five individuals were reared in tank (2.5 x 2.0 x 1.5 m) and fed macroalga every two days. Parameters such as testosterone and estradiol hormone in gonad and coelomic fluids, gonad weight, and oocyte diameter were measured every two weeks. The third phase was to know the requirement of protein and energy-protein ratio to maximize gonad production and quality. Adult sea urchins were collected from the wild and held in aquarium at laboratory. Nine formulated diet were prepared in order to examine two experimental factors: (1 protein levels (22, 27, and 32%) and (2) energy protein ratio (9, 11, 13 kcalGE/g protein). Gonad weight, protein, total carotenoid, β-carotene, colour, texture, and gonad taste were evaluated at the end of the experiment. The fourth phase was to study the effect of estradiol-17β at dose of 10 and 30 μg/g wet weight of diet for accelerating gonad maturation of sea urchin at different test diameter: 50 – 59, 60 – 69, and 70 – 79 mm. Parameter observed in this experiment were the same as that of the second phase. Result from the first phase showed gonad of sea urchin consisted of five stages of development, namely; developing/recovering, growing, pre mature, mature, and partial spawning. At the second phase, development stages of gonad were the same as observed at the first phase, gonad maturation achieved maximum at 9th week. At the third phase, the 32% protein level and 9 kcal GE/g energy-protein ratio gave higher production and gonad quality. At the fourth phase, estradiol-17β at dose 30 μg could accelerate gonad maturation of sea urchin at the 60 – 69 mm test diameter. Gonad maturation achieved maximum at 7th week. As conclusion, application of 32% protein and 9 ccal GE/g energy-protein ratio, as well as estradiol-17β could maximize gonad performance.

Bulubabi merupakan salah satu jenis biota laut yang bernilai ekonomis tinggi. Gonad bulubabi dapat dimanfaatkan sebagai bahan pangan bergizi tinggi dengan harga yang cukup tinggi. Selain itu bulubabi dapat juga dimanfaatkan sebagai hewan hias. Tingginya harga gonad di pasaran internasional, serta adanya penurunan populasi di beberapa negara mendorong pengembangan budidaya bulubabi di beberapa negara, namun di Indonesia budidaya bulubabi belum dikembangkan. Tripneustes gratilla adalah salah satu jenis bulubabi yang dominan di perairan Indonesia dan Teluk Kupang khususnya serta berpotensi untuk dikembangkan karena memiliki gonad yang rasanya enak. Pada umumnya budidaya bulubabi diarahkan untuk meningkatkan produksi (massa gonad) dan kualitas gonad (warna, rasa, dan tekstur). Produksi dan kualitas gonad dipengaruhi oleh kondisi reproduksi (tingkatan perkembangan gonad) dan kualitas nutrien. Perkembangan gonad bulubabi berbeda diantara spesies, waktu, dan tempat. Hal ini dipengaruhi oleh siklus reproduksi, musim, dan geografis. Penelitian pertama bertujuan mengkaji perkembangan gonad T. gratilla di perairan Teluk Kupang, NTT. Penelitian ini dilaksanakan selama 6 bulan dari bulan Juni hingga Desember 2008. Pengambilan sampel dilakukan setiap bulan, dengan mengamati/mengukur bobot tubuh, diameter tubuh, bobot gonad, diameter oosit, warna gonad, dan histologi gonad. Hasil penelitian menunjukkan pada setiap bulan pengamatan, ditemukan gonad berada pada beberapa tingkatan perkembangan gonad, yaitu: tingkatan berkembang dan atau pulih, bertumbuh, pra matang, matang, dan salin. Hal ini menunjukkan bulubabi T. gratilla memiliki tipe reproduksi yang asinkronis. Puncak matang gonad terjadi pada bulan Desember.