Nutritional evaluation of varying protein: energy ratios in feeds for Indian white shrimp Penaeus (Fenneropenaeus) indicus

Abstract

Six experiments of six weeks duration were conducted in controlled conditions in the Indian white shrimp Fenneropenaeus indicus early juveniles (~0.040 mg initial weight). A common ingredient mixture (CIM) consisting of albumin (chicken egg), fish meal, shrimp meal, clam meal and deoiled ground nut oil cake was formulated and incorporated in all feeds at varying levels to obtain the requisite protein: energy combinations. Eight feeds tested in each experiment were formulated by incorporating CIM, cellulose (filler), tapioca flour (starch, binder), oil, mineral mixture, vitamin mixture and other additives viz., cholesterol and lecithin. The six protein levels fixed were 250 g kg-1 to 500 g kg-1 with 50 g kg-1 increments for each experiment. The gross energy (GE) levels in the eight dietary treatments for each level of protein varied from 290 kcal 100g-1 to 430 kcal 100g-1 and the digestible energy levels varied from198 – 300 kcal 100g-1. Growth, relative growth rate (RGR), absolute growth rate (AGR), food conversion efficiency (FCE), food conversion ratio (FCR), survival and initial and final body composition were monitored and analysed. One-way analysis of variance (ANOVA) followed by comparison of means was done to examine statistically significant differences between treatments and second degree polynomial regression of the from y = a + bx + cx2 was fitted with the data for RGR on P/E ratio (mg protein kcal-1), RGR on GE and RGR on DE to derive the optimum RGR, GE, DE and P/E. The results showed that growth of shrimp was highest with 450 g kg-1 protein and 363 kcal 100g- 1 GE, 276 kcal 100g-1 DE with a P/E of 124. Theoretical optima derived confirmed this observation with optimal values of 360 kcal 100g-1 GE, 275 kcal 100g-1 DE and a P/E ratio of 125. However, similar response in growth with feeds containing 350 - 450 g kg-1 protein indicating GE requirement of 362 – 371 kcal 100g-1 and DE requirement of 262 – 276 kcal100g-1 suggested a protein sufficiency of 350 g kg-1 with a P/E ratio of 98- 103 without major variations in the whole body composition.