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A novel laxative method for crocodilians and digestibility of soybean (Glicine max) in broad-snouted caiman (Caiman latirostris)

Hilevski, Samuel, Siroski, Pablo
Aquaculture 2021 v.533 pp. 736137
Caiman latirostris, crocodiles, dietary markers, digesta, digestibility, digestion, drugs, equations, food composition, ingestion, ingredients, intestinal absorption, lactulose, nutrient content, nutrients, plant proteins, protein sources, sodium chloride, soybean meal, soybeans, vegetable oil, wet digestion method
The objectives of this study were to evaluate the laxative capacity of saline solution, vegetable oil, and a commercial drug on Caiman latirostris and determine digestibility of diets with plant derived protein sources as a supplement for this species. After a trial using three laxative treatments in different doses, caimans were treated with 1.5 mL of lactulose daily for two days. They were then force-fed their corresponding diet once per day for 7 days and then digesta residues were collected. Digestibility was determined through a dietary marker, acid digestion of digesta residues, and calculated with a standard equation. Digestion of diets were between 96 and 99%, exhibiting differences among these (P = 0.0006), with the control diet 2.45% lower than treatments diets (P = 0.0050). Digestibility of soybean meal was between 90 and 95%. There were differences according to the treatment diet (P = 0.018). The results of this study indicate that the use of lactulose as a laxative for C. latirostris is effective and does not affect health. Inclusion of soybean meal in the diet of C. latirostris at levels of 20–60% improved its digestibility and nutrients were efficiently digested. Deliberate ingestion of plant material by wild crocodilians may serve to aid digestion and absorption of dietary nutrients, and not act only as gastroliths. This information could be used to develop crocodilian diets and assist future research to determine optimum nutrient levels and ingredient combinations for farm-raised crocodilians fed compounded diets.