INFLUENCE OF DIETARY-PROTEIN CONTENT ON THE DISTRIBUTION OF AMINO-ACIDS IN OOCYTES, SERUM AND MUSCLE OF NILE TILAPIA, OREOCHROMIS-NILOTICUS(L)

In this paper changes in the physical and chemical characteristics inc luding the amino acid content of mature oocytes (Stage 4; pear-shaped; > 2.4 mm diameter) of Oreochromis niloticus females in relation to di etary protein content of 10, 20 and 35% are presented. Corresponding c hanges in amino acid content of dorsal muscle and serum (18 h post-pra ndial) were also investigated in the females sampled. The amount of pr otein in oocytes of females maintained on the 10% protein diet was sig nificantly lower (P<0.05) than the others. However, the gonadosomatic index of females and the diameter, mean weight and moisture content of oocytes were not affected significantly by the dietary protein levels . Diet related changes were observed in total (protein-bound + free) a mino acid patterns in oocytes and muscle. Total essential amino acid p atterns of muscle and oocytes were positively and significantly correl ated to those of the diets, but with respect to the total non-essentia l amino acids, only the dietary amino acid patterns for the 20 and 35% protein diets were correlated to that of muscle. Serum and oocyte fre e essential and non-essential amino acid patterns were also highly cor related with dietary amino acids at all three dietary levels. The sign ificance of these observations is discussed in light of possible 'mate rnal compensation', whereby the female attempts to channel essential n utrients to developing oocytes even when her nutrition is sub-optimal. (C) 1997 Elsevier Science B.V.