The effect of different dietary energy levels in crab-protein-based diets on digestibility, oxygen consumption, and ammonia excretion of bilaterally eyestalk-ablated and intact juvenile lobsters, Homarus americanus

The fast growth resulting from eyestalk ablation of juvenile lobsters, Homarus americanus, can be attributed to more efficient energy utilization as indicated by lower feeding metabolism, particularly the calorigenic effect of feeding and lower nitrogen excretion than found for intact lobsters. However, there was no difference in standard metabolism between ablated and intact juvenile lobsters. The apparent digestibility of dry matter by ablated lobsters was lower than intact controls when fed low energy (high protein energy ratio) and/or high α-cellulose diets. The apparent lipid digestibility was reduced by eyestalk ablation, whereas there was no effect of ablation on apparent protein digestibility. The apparent digestibilities of dry matter and energy improved with increased dietary energy and/or decreased α-cellulose levels in both ablated and intact lobsters. However, while apparent digestibilities of protein and lipid also increased with dietary energy in ablated lobsters, for intact lobsters the apparent digestibility of protein was relatively constant and apparent digestibility of lipid reached a peak at intermediate levels of dietary energy. The dependence on protein for energy utilization may be greater for ablated lobsters. The energy budget equation of lobsters constructed from the data obtained in this study will be very useful for understanding energy utilization of lobsters.