Dietary Premix Levels, Calcium and Phosphorus Ratios on Growth Performance of Juvenile Rice-field Crabs (Esanthelphusa dugasti)

Abstract

Two experiments were conducted at the Department of Fisheries, Khon Kaen University, Nong Khai campus during June to November 2014 to investigate effects of dietary premix levels, calcium and phosphorus ratios on growth performance and survival rate (%) of juvenile rice-field crabs (Esanthelphusa dugasti). The objectives in carrying out this work include an evaluation on the effects of different levels of supplementary premix (Experiment1), calcium and phosphorus ratios on growth performance and survival rate of the rice-field crabs (Experiment 2). Experiment 1 consisted of five treatments of five levels of supplementary premix, i.e. 0, 1, 2, 3 and 4 g kg-1 of diet for T1 up to T5, respectively. With Experiment 2, five ratios between Ca and P were used, i.e. 1.1: 1.0 (T1 control), 2.1:1.0 (T2), 2.4:1.0 (T3), 3.1:1.0 (T4), and 3.5:1.0 (T5). A Completely Randomized Design (CRD) with four replications was used for both Experiments. The results of the Experiment 1 showed that the supplementary premix added to the feed diet was found to be a significant contributor in increasing both width and length of carapace and molting frequency of the rice-field crabs. An amount of 3g kg-1 of T4 added to the formulated diet gave the highest growth in width, and length of carapace and molting frequency of the rice-field crabs. An increase in dietary premix to the feed diet significantly increased weight gained (WG), average daily growth rate (ADG), specific growth rate (SGR %) and survival rate (SR %) of the rice-field crabs. For the Experiment 2, the highest mean values of carapace width, length and molting frequency of the ricefield crabs were found with a ratio between Ca and P of 2.4:1 (T3). An amount of 3g kg-1 of T4 added to the formulated diet gave the highest growth in width, and length of carapace and molting frequency of the rice-field crabs. An increase in dietary premix to the feed diet significantly increased weight gained (WG), average daily growth rate (ADG), specific growth rate (SGR %) and survival rate (SR %). The highest mean values of carapace width, length and molting frequency of the rice-field crabs were found with T3 with a ratio between Ca and P of 2.4:1.