EVACUATION OF INERT MARKERS IN DIGESTIBILITY DETERMINATION, 5-ALPHA-CHOLESTANE AND CHROMIC OXIDE, IN THE PRAWN PENAEUS-JAPONICUS

The rate of movement, recovery, correlations between markers and nutri ents were determined in prawn Penaeus japonicus using inert markers, c hromic oxide and Sor-cholestane, The mean retention times of cholestan e and chromic oxide in the gastro-intestinal tract were 14.5 h and 7.2 h, respectively. This result suggested a different rate of movement o f the two markers in the gastro-intestinal tract of prawns. There was a significant correlation (r=0.97) between the fecal cholestane and ch olesterol contents. Cholestane also showed a high recovery and low abs orption in the prawn body. These results of the present study indicate d that cholestane is superior to chromic oxide as lipid digestibility marker in P. japonicus.