The effect of diet on the growth and energy budget of juvenile <i>Neostichopus grammatus</i>

ABSTRACT Providing optimum energy levels in diets for sea cucumbers is essential, as an excess or inadequate energy level can lead to a reduced growth rate. This study investigated the effect of diets on the growth and energy budget of juvenile sea cucumber Neostichopus grammatus for twelve weeks. The diets are abalone waste (AB); abalone waste mixed with powdered Ulva lacinulata (A + U) and Gracilaria gracilis ; abalone (A + G), formulated pellet with the inclusion of sand (P + S) and without sand (P – S). Ingestion rate was influenced by diets, such that diets, containing abalone waste (AB, A + G and A + U), exhibited higher ingestion rates ( p &lt; 0.05) and consequently higher faecal production rates than that fed pellet (P – S and P + S). The diets affected the energy consumed from food assimilation ( C ), energy lost in faeces ( F ) and energy lost through ammonia excretion ( U ). However, the diets did not influence the energy available for growth ( G ), and the energy lost through respiration ( R ). 81–96% of energy intake was lost to R. The diets had no significant effect on G, as sea cucumbers in the various treatments all had a low and negative proportion of energy allocated to growth regardless of the feed ingested. This study has shown that the sea cucumber N. grammatus spends 81–96% of its ingested energy on respiration, leading to a deficit of energy available for growth. HIGHLIGHTS Diets affected the energy lost through ammonia excretion. Diets used in this study did not influence the energy available for growth, and the energy lost through respiration 81%–96% of energy intake than expected was lost to respiration Sand substrate in tanks is essential for the land‐based rearing of N. grammatus