Effect of dietary protein levels on growth of Penaeus stylirostris juveniles

The shrimp Penaeus stylirostris is currently produced on a commercial scale in Tahiti and New Caledonia. Both super-intensive (80 animals m(-2)) and semi intensive (25 m(-2)) systems are promoted. Locally produced commercial feed contains 380-400 g kg(-1) crude protein (CP) without special consideration for environmental impact. The need for a 'low pollution' diet implies reconsideration of the optimum dietary protein level for this species. Under experimental conditions, six isoenergetic practical diets ranging from 270 g kg(-1) to 440 g kg(-1) CP were formulated and fed to satiation for 30 days to juvenile P. stylirostris; average growth rates were between 5.5 and 7.5 g per month with survival rates >90%. The lowest protein levels 270-310 g kg(-1), gave significantly (P<0.05) poorer growth (5.5 g per 30 days) than was observed with 330-430 g kg(-1) CP; 330 g kg(-1) CP may be recommended, and as it is lower than levels in diets used currently, there is a possibility of reducing nitrogenous waste. In addition to growth response, protein efficiency ratio, protein productive value and food conversion (feed/gain) all supported a recommended dietary protein level of 330 g kg(-1). Future prospects for practical feeds with even lower CP levels are considered.