EFFECTS OF DIETARY STEARIC-ACID AND PROTEIN-LEVELS ON THE UTILIZATIONOF STEARIC-ACID BY FRESH-WATER PRAWN MACROBRACHIUM-ROSENBERGII JUVENILES

The effects of dietary stearic acid (SA) and crude protein (CP) levels on the utilization of SA as an energy source by freshwater prawn Macr obrachium rosenbergii (de Man) were determined by feeding and tracer e xperiments. Feeding experiments showed that M. rosenbergii juveniles f ed diet 2 (2% SA+35% CP) gave significantly higher (p<0.05) weight gai n, feed conversion efficiency (FCE), and protein efficiency ratio (PER ) than those fed diet 4 (7% SA+50% CP), which provided the lowest weig ht gain, FCE, and PER. Diet 2 tended to give higher weight gain than d iets 1 (0% SAS 35% CP) and 3 (7% SA+35% CP), but no significant differ ence existed among the 3 dietary groups. The higher weight gain of pra wns fed diet 2 (2% SA) compared with diet 1 (0% SA) indicated the posi tive contribution of SA as an energy source. Significantly higher SA a nd oleic acid levels were observed in prawns fed diets with 7% SA than those fed with 2% SA, indicating that dietary SA affected body fatty acid profile. Prawns fed diets containing 35% CP had significantly hig her PER than those fed 50% CP diets. Tracer experiments showed that M. rosenbergii juveniles utilized SA as an energy source as evidenced by expired (CO2)-C-14 after feeding with [C-14]SA. Expired (CO2)-C-14 ac counted for half of ingested radioactivity 48 h after feeding with lab elled diets. The prawns fed diets containing 35% CP expired much more (CO2)-C-14 than those fed diet containing 50% CP, but no significant d ifference was detected (p>0.05).