Sunflower oil cake as a replacement for fish meal in feeds of Tiger Shrimp, Penaeus monodon reared in tanks and in net cages

摘要

Replacement of fish meal in marine shrimp feeds is assuming greater importance due to increasing economic and ecological considerations. This study evaluated sunflower cake as a replacement for fish meal in tiger shrimp Penaeus monodon juveniles reared both in tanks and in net cages at 26-33 ppt salinity. Five practical diets were prepared by incorporating sunflower cake at 0, 2.5, 5, 7.5 and 10% level by replacing fish meal. The essential amino acid index (EAAI) of test diets ranged from 0.91 to 0.88. Growth and digestibility study was conducted for 45 d in 500 L experimental tanks shrimp weighing 0.51+0.02 g with three replications for each treatment. There were significant (P<0.05) reductions in ' daily growth coefficients and protein utilization efficiency in shrimp fed with diets having above 2.5% sunflower cake in experimental tanks. The lysine and methionine digestibility (92.4±0.11 and 93.4+0.01%, respectively) was significantly (P<0.05) higher at 2.5% level inclusion than at 10% level (81.67+0.12 and 83.36+0.17%, respectively). The free amino acid profiles of shrimp muscle at 4 h post feeding indicated significantly (P<0.05) lower levels for isoleucine, leucine, lysine and valine in shrimp fed with higher level of sunflower cake. The decreased levels of these essential amino acids could have hampered protein synthesis and in turn growth. With three dietary treatments (0, 5 and 10% sunflower cake diets) a 10-week growth trial was also conducted in net cages with tiger shrimp juveniles weighing 0.2 g. Significantly (P<0.05) lower daily growth coefficients (%/d) were observed in shrimp fed with 10% sunflower cake diet (1.642+0.017) compared to control (1.774+0.024). The results indicate that sunflower cake can be incorporated up to 5% by replacing 20% of fish meal in marine shrimp P. monodon practical feeds without compromising growth.