Carbohydrates in fish nutrition: effects on growth, glucose metabolism and hepatic enzymes

Abstract

The utilisation of dietary carbohydrates and their effects on fish metabolism are reviewed. Details on how dietary carbohydrates affect growth, feed utilisation and deposition of nutrients are discussed. Variations in plasma glucose concentrations emphasizing results from glucose tolerance tests, and the impact of adaptation diets are interpreted in the context of secondary carbohydrate metabolism. Our focus then shifts to selected aspects of hormonal regulation of carbohydrate metabolism and dietary carbohydrates and their variable effects on glycogen and glucose turnover. We analyse the interaction of carbohydrates with other nutrients, especially protein and protein sparing, and de novo synthesis of lipids, and finish by discussing the correlation of dietary carbohydrates with fish health.

Enzimas digestivas exógenas na alimentação de juvenis de tambaqui

“…Uma hipótese para a obtenção desse resultado seria o fato de a amilase ter disponibilizado uma quantidade excessiva de glicose, oriunda de ingredientes como o farelo de soja, fubá de milho e farinha de trigo contidos na ração, depositando glicogênio em excesso no fígado dos peixes e prejudicando assim o seu crescimento (Hemre et al, 2002). Este fenômeno torna obrigatório o monitoramento da capacidade do fígado dos peixes em metabolizar e armazenar carboidratos (Legate et al, 2001).…”

Nutritional homeostasis in carnivorous southern catfish (Silurus meridionalis): is there a mechanism for increased energy expenditure during carbohydrate overfeeding?

“…Gluconeogenesis is the main process involved in meeting body glucose needs in carnivorous fish due to the lack of carbohydrate in natural diet (Cowey et al, 1977). The research on intermediary metabolism of carbohydrate suggests that lack of regulation of hepatic gluconeogenesis is common in carnivorous fish compared to mammal (Panserat et al, 2001a;Hemre et al, 2002). This is perhaps due to the difference in structure and function of related hormone (insulin, insulin-like growth factor-I (IGF-I) and glucagons) and their receptors (Mommsen and Moon, 1990;Mommsen and Plisetskaya, 1991;Plisetskaya and Mommsen, 1996;Navarro et al, 1999;Moon, 2001).…”

“…This is particularly distinct in carnivorous fish (see review in Hemre et al, 2002) thus leading to prolonged hyperglycemia (Deng et al, 2001) and higher liver glycogen (Suarez et al, 2002) after feeding higher dietary carbohydrate. This is due to the minor role of carbohydrate as a metabolic fuel compared to protein (West et al, 1993;Weber and Haman, 1996) and its poor capacity for lipid synthesis in some fishes compared to mammals (Hillestad et al, 2001).…”

“…According to Cowey et al (1977), liver glycogen cannot be considered an immediate source of glucose in this species, since gluconeogenesis is the main process involved in meeting glucose needs. So with long-term carbohydrate overfeeding the deposited glycogen may dissipate useless other than provide energy fuel (Suarez et al, 2002;Hemre et al, 2002).…”

Hepatocyte Nuclear Factor 4α Transactivates the Mitochondrial Alanine Aminotransferase Gene in the Kidney of Sparus aurata

“…The limited capacity to metabolize dietary carbohydrates and a metabolic profile that mimics non-insulin-dependent diabetes mellitus in mammals after a glucose load, led to consider these animals as glucose intolerant (Cowey and Walton, 1989;Moon, 2001;Hemre et al, 2002).…”