Yolk utilization in an estuarine edible crab Thalamita crenata (Latreille)

Abstract

Changes in chemical composition, calorific content, cumulative yolk utilization
efficiency, energy conversion efficiency, water metabolism and ash metabolism were
studied in the developing eggs of Thalamita crenata. During embryogenesis, water
content increased from 60.96 to 89.38%, ash increased from 2.06 to 14.34% fat level
increased from 20.76 to 37.45% and carbohydrate level increased from 4 to 5.03%.
On the contrary, protein content decreased from 73.18 to 43.18%. Cumulative yolk
utilization efficiency values of the various yolk constituents were 51.69% for dry
weight, 45.21% for organic substances, 46.15% for energy, 30.43% for protein, 93.37%
for fat and 65.63% for carbohydrate. The gross energy conversion efficiency was
46.15% and hence the total energy loss during embryonic development was 53.85%.
For embryonic metabolism dry yolk substance of 3.86 ug was used up. A single egg
contained 0.1911 Joules. During the metabolism protein, fat and carbohydrate
contributed 93.85, 4.21 and 1.84% of energy respectively, for the total embryonic
development. A single egg of wet weight 20.466 ug demanded 22.283 ug water for
the successful completion of embryonic development. A single developing egg
required 0.43 ug of inorganic salt during embryogenesis. In the present study,
protein metabolism was geared up and fat metabolism was suppressed.