Glucose tolerance in six fish species reared in Brazil: Differences between carnivorous and omnivorous

Abstract

The objective of this study was to evaluate the effect of pure glucose, glucose plus fructose, and fructose on the blood glucose of omnivorous fi sh tambaqui (Colossoma macropomum), Nile tilapia (Oreochromis niloticus), piau (Leporinus elongatus), and carnivorous fi sh hybrid Amazon catfi sh (Pseudoplatystoma fasciatum × Leiarius marmoratus), pacamã (Lophiosilurus alexandri), and traíra (Hoplias malabaricus). In each species, the dose 1 mL per fi sh with 1,000 mg kg of body weight -1 of glucose, fructose or glucose plus fructose were tested intraperitoneally. Blood glucose was measured at times 0 (control), 0.5, 1, 2, 4, 8, 16, and 24 h. The administration of 1,000 mg of glucose or glucose plus fructose per kg of live weight causes hyperglycemia in the omnivorous and carnivorous species studied. In the omnivorous species, glycemic levels were reduced from 2 to 4 h, and the regulation to baseline occurred from 4 to 8 h. In the carnivores fi sh, blood glucose levels declined between 1 and 8 h, and return to baseline was observed from 8 to 16 h. Tambaqui was also intolerant to high concentrations of fructose. Blood glucose levels are regulated in a shorter time in Nile tilapia (mainly), piau and pacamã.

Digestible threonine requirement in tambaqui ( Colossoma macropomum ) diets: Growth, body deposition, haematology and metabolic variables

“…Protein is the component of food that is considered an essential nutrient in aquaculture, influencing fish growth and maintenance. Diets with high crude protein levels are the most expensive and result in increased excretion of nitrogenous compounds into the water (de Souza et al, 2020). Furthermore, a diet formulated solely based on crude protein may not guarantee that the metabolic needs of fish are met for amino acids (Marchao et al, 2020).…”

Addition of essential oil from lemongrass to the tambaqui ( Colossoma macropomum ) diet: Effects on growth, intestinal enzymes, haematological and metabolic variables, and antimicrobial challenge

“…Tambaqui is responsive to the food composition, adapting its main digestive enzymes to the best profile (De Almeida et al, 2006). Still, it reduces its glycemic level slowly because it can remain hyperglycemic for a long time (De Souza et al, 2021). In addition, outbreaks of bacterial diseases are responsible for economic losses in the intensive cultivation of tambaqui, including bacteriosis caused by Aeromonas hydrophila (Tavares‐Dias & Martins, 2017).…”