Feed intake and its relation to foregut capacity in juvenile spiny lobster,Jasus edwardsii

Abstract

Limited food consumption has been identified as a possible reason for the poor growth in spiny lobsters raised on dry formulated diets. Food intake was determined for different sized juveniles (20-80 g) of the spiny lobster, Jasus edwardsii, fed either fresh mussel flesh or a dry formulated diet for 0.5-5.0 h every 48 h. In addition, the foregut capacities of lobsters of various sizes were measured to relate food intake to foregut fullness. Food intake was relatively rapid on both diets (1 h) and reached mean dry matter threshold values (mean satiation rations) that were related to foregut capacity. Foregut capacity increased linearly with body weight (BW; 10-110 g) and restricted dry matter intake of lobsters to an average of 0.8-1.2% BW regardless of diet. Both wet and dry diets, when fed in equal amount of dry matter, were found to have similar wet weights in the foregut after ingestion. Allowing lobsters more time to feed (2 to 5 h) had no significant effect on mean dry matter intake because the foregut filled to maximum capacity within 1 h. The results suggest that /. edwardsii juveniles have a small foregut capacity (2.5-3% BW) that limits food intake when diets are fed every 48 h. There appears to be no advantage in dry matter intake by providing the nutrient-dense dry formulated diet of this study compared with mussel M07068; flesh. Formulated diets would need to be fed more frequently and be highly digestible if they are to deliver sufficient nutrition to maximise growth for commercial aquaculture.

A Global Review of Spiny Lobster Aquaculture

“…Simon and Jeffs (2008) studied feeding and gut evacuation rates in J. edwardsii and reported that a slow appetite revival and diffi culties in processing and digestion of formulated diets appear as major issues to be resolved to improve the performance of formulated diets for spiny lobsters. Simon (2009a) studied feed intake and its relation to foregut capacity in juvenile J. edwardsii. The results indicated that J. edwardsii juveniles have a small foregut capacity (2.5 -3% BW) that limits food intake when diets are fed every 48 hours.…”

Digestive physiology of spiny lobsters: implications for formulated diet development

“…A similar apparent intake (1% BW day À1 ) was also recorded for P. cygnus juveniles (2-7 g) fed a dry pellet (Johnston et al 2007), which is much lower than the daily food consumption of other cultured crustacean such as penaeid shrimps (for instance, 5% BW day À1 in Penaeus monodon; Smith et al 2005b). It was demonstrated that J. edwardsii juveniles cannot achieve high levels of feed consumption on formulated feeds due to a small foregut capacity (2-3% of body weight), expansion of the feed post-immersion and post-ingestion, lengthy foregut filling time (1-2 h) and clearance time (10 h), combined with a slow gut throughput time (34-42 h) and appetite revival (>18 h) (Simon & Jeffs 2008;Simon 2009a). These attributes limit the level of food consumption to the equivalent of the capacity of one foregut per day, that is, 1-1.5% BW day À1 for ingested material with dry matter <50%.…”

“…Seawater intake during feeding is an issue that deserves further research because it allows the formulated diet components to dissolve but significantly dilutes the digestive enzymes present in the gastric juice (Simon 2009b;Perera et al 2012b), reduces the maximum dry matter intake per meal (Simon 2009a), and probably elevates the pH of the gastric juice (Simon 2009b). Various studies indicate that the mouthparts of juvenile spiny lobsters are suitable for the mastication of solid food particles (Nishida et al 1990;Wolfe & Felgenhauer 1991;Lemmens & Knott 1994), although early instar juveniles do not appear to effectively manipulate and ingest harder, dry feeds (Cox et al 2008).…”

“…Various studies indicate that the mouthparts of juvenile spiny lobsters are suitable for the mastication of solid food particles (Nishida et al 1990;Wolfe & Felgenhauer 1991;Lemmens & Knott 1994), although early instar juveniles do not appear to effectively manipulate and ingest harder, dry feeds (Cox et al 2008). When juvenile J. edwardsii are fed fresh mussel, little seawater is ingested due to less mouthpart manipulation of the food which is swallowed in large portions of flesh rather than being reduced to a slurry by the mouthparts prior to ingestion (Simon & Jeffs 2008;Simon 2009a). Studying mouthpart morphology in juveniles has provided insight into optimizing pellet size to increase food intake and minimize leaching and fragmentation (Cox et al 2008).…”

“…The use of more digestible protein binders such as gelatine and transglutaminase than commonly used alginate was shown to improve apparent digestibility (Simon 2009d). Feeding soft pellets of the right size to reduce trituration at the level of the mouthparts (Smith et al 2009a,b) and avoid excessive rehydration postimmersion and in contact with the gastric fluid in the foregut (Simon 2009a) should be also tested. Finally, improving the solubility of dietary macronutrients, without compromising feed stability, leaching losses and palatability, is an essential step to improve the chemical digestion of feeds.…”