STUDIES ON DIETARY PROTEIN REQUIREMENT OF Litopenaeus vannamei (BOONE, 1931) JUVENILES REARED IN INLAND SALINE WATER

India has vast coastal brackishwater resources of over1.2million ha for culture of brakishwater finfish and shellfish. In addition to these coastal resources, 8.62 million ha of inland saline soils has potentials for its use in aquaculture. Pacific white shrimp, Litopenaeus vannamei is being successfully cultured in coastal brackishwater areas in salinity ranging from 0.5 to 30 ppt. The availability of specific pathogen free and specific pathogen resistant seed of this species has made it a species of choice for profitable aquaculture in recent years. However, the information on the dietary protein requirement of whiteleg shrimp juvenile remains a bottleneck for the development of eco-friendly feed for grow-out culture in Inland Saline water.

Therefore, a 60-days feeding trial was conducted at the wet laboratory of ICAR-CIFE, Rohtak Centre, Haryana, India to assess the dietary protein requirement of whiteleg shrimp juveniles for optimum growth. Seven iso-energetic and hetero-nitrogenous semi-purified diets with graded levels of crude protein such as 20% (D-1), 25% (D-2),30% (D-3), 35% (D-4), 40% (D-5), 45% (D-6) and 50% (D-7) were prepared and fed to juveniles (average weight 8.15±0.41 g) of respective group in triplicates with stocking density of 15 acclimated healthy shrimp per tank of 300-L capacity (water level 250-L) with aeration following a completely randomized design. The growth of L. vannamei juvenile were significantly affected by the different dietary CP levels (P<0.05). The results showed that the growth of the fish increased significantly (P<0.05) with increasing protein levels up to 35% and decreased thereafter. Maximum SGR (1.23±0.01% day^-1), weight gain (109.04±1.06%) and minimum FCR (2.09±0.02) was found in D-4 (35% CP) group. All these parameters were negatively affected with the further increase in protein level in the diet. Moreover, the PER was found to decrease with increasing dietary protein levels (P<0.05). However, based on second-order polynomial regression analysis of SGR, the optimum dietary protein requirement for L. vannamei was found to be 36.47%. These findings will be useful for the formulation of cost-effective and eco-friendly diets for whiteleg shrimp, L. vannamei.