Feeding and gut evacuation of cultured juvenile spiny lobsters, Jasus edwardsii
Simon, CJ and Jeffs, A, Feeding and gut evacuation of cultured juvenile spiny lobsters, Jasus edwardsii, Aquaculture: An International Journal Devoted to Fundamental Aquatic Food Resources, 280, (1-4) pp. 211-219. ISSN 0044-8486 (2008) [Refereed Article]
Low feed consumption has been suggested as a major impediment for the development of effective
formulated diets for spiny lobsters. To seek an explanation for the low feed consumption, this study
compared the feed consumption, appetite revival, foregut evacuation and fecal production of different sizes
of spiny lobster Jasus edwardsii juveniles fed a fresh natural diet (i.e. mussel flesh) and a dry formulated diet.
In addition, the effect of feeding frequency was determined by feeding juvenile lobsters the same ration of
formulated diet at different time intervals. i.e., same ration delivered 3 week−1, 1 day−1, 2 day−1, 5 day−1 and
5 night−1. Lobster (10–15 g) growth and feed consumption (1.15% BW day−1) was maximized when receiving
a single ration daily of the formulated diet. A slow appetite revival (ARN18 h) on the formulated diet was
consistent with the negative effect of increasing feeding frequency on growth and consumption. In addition,
there appeared to be no major advantage in dry matter intake by providing the nutrient dense dry
formulated diet to Jasus edwardsii. Lobsters fed fresh mussel flesh (79.8% moisture) consumed similar levels
of dry matter as those lobsters fed the dry formulated feed (7.3% moisture). This appears to be due to high
moisture gain and expansion of the dry feed in the lobster foregut. Foregut evacuation lasted 10 h for the two
diets but a delay in initial foregut evacuation and processing of the formulated diet was evident, and may
have negatively affected feed consumption, appetite revival and dry matter digestibility (61.2%) of the dry
formulated diet compared to the mussel flesh diet (89.2%). Appetite revival on mussel flesh was almost
complete by 12 h after a satiation ration and was governed primarily by the rate of foregut evacuation.
Differences in the timing of foregut evacuation and fecal production between the two diets suggested that a
greater proportion of the formulated diet entered the midgut directly.
The results indicate that J. edwardsii cannot achieve high levels of feed consumption on formulated diets
because gut throughput is reduced due to a small foregut capacity, expansion of the feed post-ingestion,
lengthy foregut filling time (1–2 h) and clearance time (10 h), combined with slow gut throughput time (34–
42 h) and appetite revival (N18 h). A slow appetite revival and difficulties in processing and digestion of
formulated diets appear as major issues to be resolved to improve the performance of formulated diets
required for the commercial aquaculture of J. edwardsii and possibly other spiny lobsters.