RESPONS FISIOLOGIS DAN KINERJA PERTUMBUHAN IKAN NILA PADA MEDIA RENDAH AMONIA DAN DIBERI SUPLEMEN ASAM GLUTAMAT - Titin Kurniasih; Dedi Jusadi; Muhammad Agus Suprayudi; Sri Nuryati; Muhammad Zairin Jr.; Eddy Supriyono (Pusat Riset Perikanan, Badan Riset dan Sumber Daya Manusia Kelautan dan Perikanan, 2020)
Ketika dipapar media tinggi amonia, ikan nila mengalami perubahan metabolisme asam amino yang cukup signifikan, dan suplementasi asam glutamat berguna untuk memperbaiki perubahan yang merugikan akibat paparan amonia. Akan tetapi informasi mengenai aspek metabolisme asam amino pada ikan nila yang dipapar amonia rendah masih sangat terbatas. Penelitian ini dilakukan untuk mengevaluasi pengaruh suplementasi asam glutamat pada ikan nila merah yang dipelihara pada media budidaya rendah amonia terhadap respons fisiologis dan kinerja pertumbuhan. Ikan nila dengan bobot rata-rata 9,97 ± 0,38 g ditebar sebanyak 20 ekor pada setiap akuarium (padat tebar 1,0 g L-1). Empat jenis pakan isoprotein (kadar protein 28%) dan isoenergi (4245 ± 22,48 kkal kg-1) disuplementasi asam glutamat masing-masing sebanyak 0% (Glu 0), 0,75% (Glu 0,75), 1,5% (Glu 1,5) dan 2,25% (Glu 2,25). Setiap perlakuan diberi empat ulangan. Penelitian ini dilakukan selama 60 hari. Hasil penelitian menunjukkan bahwa pemberian pakan yang ditambah glutamat memberi efek pada respon fisiologis ikan. Aktivitas enzim aspartate aminotransferase (AST) pada Glu 2,25 lebih rendah dibandingkan dengan perlakuan lainnya, yang menjadi indikasi penurunan beban kerja hati. Ada kecenderungan peningkatan kadar aspartat, alanin, leusin, isoleusin dan valin pada jaringan hati seiring dengan meningkatnya kadar suplementasi asam glutamat. Di dalam penelitian ini, kinerja pertumbuhan ikan tidak berbeda nyata antar perlakuan. Kesimpulannya adalah bahwa konsumsi pakan yang ditambah asam glutamat 2,25% mampu memperbaiki respons fisiologis ikan akibat menurunnya beban kerja hati yang dicirikan dengan penurunan nilai AST, serta meningkatnya kandungan beberapa asam amino hati, walau belum mampu memperbaiki kinerja pertumbuhan dan pemanfaatan pakan oleh ikan nila. Informasi ini berguna untuk pengembangan riset terkait aspek metabolisme asam amino pada ikan nila yang terpapar media tinggi amonia.When exposed to high ammonia aquatic environment, nile tilapia experienced a significant change in hepatic amino acid metabolism and glutamic acid supplementation can reduce the effects of the adverse change. However, there are no sufficient information on the amino acid metabolisme of tilapia exposed to low environmental ammonia. This research was performed to evaluate the effects of oral supplementation of glutamic acid on the aminotransferase enzymes activity and growth performance of red tilapia reared in low environmental ammonia (LEA) with NH4 concentration of 0.10 mg L-1. Fish with an average weight of 9.97 ± 0.38 g were stocked with an initial rearing density of 1.0 g L-1(20 fish in each aquarium). Four isonitrogenous (crude protein 28%) and isocaloric (4246 ± 22.48kcal kg-1) experimental diets were prepared with supplementation of different ratios of glutamic acid at 0% (Glu0), 0.75% (Glu0.75), 1.5%(Glu1.5) and 2.25 % (Glu2.25) to feed, respectively. All treatment groups were arranged quadruplicate. Fish were fed with the diets for 60 days. The results showed that the supplementation of glutamic acid in the diet affected the physiological response of the fish. The aspartate aminotransferase (AST) activity of Glu2.25 was significantly lower compared to that of the other treatments, which indicated a decrease in liver workload. There is a tendency of increased levels of hepatic free aspartate, alanine, leucine, isoleucine, and valine following the increase of glutamic acid supplementation level. The fish growth performance was insignificantly different between the treatments. It is concluded that a diet supplemented with 2.25% of glutamic acid could improve the physiological response of red tilapia, although no significant growth improvement should be expected. These research finding could serve as an important basic information for future research on amino acid and endogenous ammonia metabolism in nile tilapia exposed to high ammonia aquatic environment.