Protein sources influence both apparent digestibility and gastrointestinal evacuation rate in juvenile slipper lobster (Thenus australiensis)

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 265; p. 111121
• Main Authors: Wirtz, Andrea, Carter, Chris G., Codabaccus, M. Basseer, Fitzgibbon, Quinn P., Townsend, Ashley T., Smith, Gregory G.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2022
• Subjects: Animal Feed - analysis; Animal Nutritional Physiological Phenomena; Animals; Apparent digestibility; Diet; Digestion - physiology; Feces; Gastrointestinal; Gastrointestinal Tract; Glycine max - metabolism; Lobster aquaculture; Nephropidae; Protein sources; Apparent digestibility; Protein sources; Gastrointestinal; Lobster aquaculture
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2021.111121

Apparent digestibility and gastrointestinal evacuation rate were measured to assess the potential of five commercially available protein sources for their inclusion in feeds for juvenile slipper lobster, Thenus australiensis. Protein sources tested were fishmeal, krill meal, lupin meal, soybean meal and squid by-product meal. Apparent digestibility of crude protein ranged from 79.6% to 95.3%, with fishmeal protein significantly less digestible than lupin meal, squid by-product meal and soybean meal. Gastrointestinal evacuation rate was estimated from marker replacement, where yttrium oxide replaced ytterbium oxide. Faeces were collected every 3 h for 48 h, and a kinetic model was used to calculate the rate and time for the second marker to replace the first marker. Gastrointestinal evacuation (≥ 95%) was completed between 4 and 6 h with no significant differences among protein sources. Faeces consisted of both markers in equal parts 2.7 to 5.0 h after the feed switch, with lupin meal reaching the midpoint significantly faster than squid by-product meal and reference feed. The present study is the first in crustaceans to examine the relationship between apparent digestibility and gastrointestinal evacuation, showing more digestible protein sources had slower evacuation rates. The combined approach provides deeper insight into crustaceans' digestive physiology and helps understand their ability to digest specific ingredients. Further research is recommended to understand protein requirements in a broader context to verify highly digestible protein sources meet all nutritional requirements.
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•First description of the relationship between apparent digestibility and gastrointestinal evacuation rate in crustaceans.•Crude protein from lupin meal, squid by-product meal, and soybean meal was significantly more digestible than fishmeal.•The marker replacement method is a new approach for crustaceans and has the advantage of allowing a natural feeding regime.•The fastest reported gastrointestinal evacuation in crustaceans with a completion (≥ 95%) between 4 and 6 h.•More digestible protein sources have slower evacuation rates.