Effects of handling stress and moulting cycle on reproductive performance and digestive capacity of female giant freshwater prawn, Macrobrachium rosenbergii

Abstract

Energy metabolism is a critical component in assessing the fundamental aspect of organism fitness in prawn aquaculture farming. This is particularly important to maintain sustainable energy use to cope with stress and tolerance without affecting growth and reproduction functions. This study aims to determine and compare energy utilisation with a special focus on reproductive performance and digestive capacity concerning the handling-stress and moulting cycle of female Giant Freshwater Prawn, Macrobrachium rosenbergii. There were two experimental groups, which are (i) grow-out pond-reared (G1): prawns were sampled randomly and concurrently for one day at an outdoor condition, and (ii) short-term maintenance (G2): prawns were transported to an indoor hatchery, acclimated for two weeks, and sampled by staggered-method for two consecutive months. For the respective experimental conditions, haemolymph from five females was sampled at eight different moulting stages, whereby each stage was classified as reproductive and non-reproductive moulting cycles. Cultivated females at the grow-out pond had higher levels of haemolymph glucose (p < 0.05) at Sub-stages D1 (0.51 ± 0.12 mg/mL), D3 (0.50 ± 0.05 mg/mL), and A (0.71 ± 0.09 mg/mL) during the reproductive moulting cycle compared to the short-term maintenance at similar moulting stages. Other findings showed that cultivated prawns at the grow-out pond had significantly (p < 0.05) higher glucose levels at Sub-stages D3 (0.57 ± 0.09 mg/mL) and B (0.37 ± 0.03 mg/mL) during the non-reproductive moulting cycle compared to the short-term maintenance indicating that energy was utilised to cope with the handling stress. We suggest that short-term maintenance may reduce the stressors factor and is applicable for hatchery operations to maintain the health of the prawn.