The Israeli Journal of Aquaculture - Bamidgeh 55(1), 2003, 69-76

Short Communication
AMMONIA NITROGEN EXCRETION RATE -
AN INDEX FOR EVALUATING PROTEIN QUALITY
OF THREE FEED FISHES FOR THE BLACK SEA TURBOT


Murat Yigit¹* , Shunsuke Koshio² , Orhan Aral¹ , Burcu Karaali¹ and Sedat Karayucel¹

1 Laboratory of Fish Nutrition, Department of Aquaculture, Faculty of Fisheries, Ondokuz Mayis University, Sinop 57000, Turkey
2 Laboratory of Aquatic Animal Nutrition, Faculty of Fisheries, Kagoshima University, Shimoarata 4-50-20, Kagoshima 890-0056, Japan


(Received 25.8.02, Accepted 18.11.02)

Key words: ammonia excretion rates, feeds, protein sources, turbot, water quality

Abstract

Total ammonia nitrogen excretion rates were measured in young Black Sea turbot (74.79 g avg wt) reared in brackish water (17 ppt salinity) at 110.3C. Duplicate groups of turbot were fed a fixed quantity of teleosts, either anchovy (Engraulis encrasicolus), goby (Gobius sp.) or whiting (Merlangius merlangus). Feeds were offered to the turbot as wet feed. Cumulative ammonia-N excretion over a 6-hour period was significantly lower (p<0.05)in fish fed goby (3.640.27 mg-N/ 100 g fish) and whiting (3.830.13 mg-N/100 g fish) than that in fish fed anchovy (4.480.06 mg-N/100 g fish). The ammonia-N excretion rate in all groups peaked two hours after feeding, but the peak value in the group fed anchovy was significantly higher (p<0.05)than in the other two groups. No differences were observed among diets in samples taken 3, 4, 5 and 6 hours after feeding. Significantly lower excretion levels in the goby and whiting groups could be related to the protein quality of these species which may be higher than that of the anchovy for turbot nutrition.


*Corresponding author: Fax: 90-368-2876255, e-mail: muratyigit@ttnet.net.tr

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