Dietary electrolyte balance affects growth performance, amylase activity and metabolic response in the meagre (Argyrosomus regius).
Dietary ion content is known to alter the acid-base balance in freshwater fish. The current study investigated the metabolic impact of acid-base disturbances produced by differences in dietary electrolyte balance (DEB) in the meagre (Argyrosomus regius), an euryhaline species. Changes in fish performance, gastric chyme characteristics, pH and ion concentrations in the bloodstream, digestive enzyme activities and metabolic rates were analyzed in meagre fed ad libitum two experimental diets (DEB 200 or DEB 700mEq/kg) differing in the Na2CO3content for 69days. Fish fed the DEB 200 diet had 60-66% better growth performance than the DEB 700 group. Meagre consuming the DEB 200 diet were 90-96% more efficient than fish fed the DEB 700 diet at allocating energy from feed into somatic growth. The pH values in blood were significantly lower in the DEB 700 group 2h after feeding when compared to DEB 200, indicating that acid-base balance in meagre was affected by electrolyte balance in diet. Osmolality, and Na+and K+concentrations in plasma did not vary with the dietary treatment. Gastric chyme in the DEB 700 group had higher pH values, dry matter, protein and energy contents, but lower lipid content than in the DEB 200 group. Twenty-four hours after feeding, amylase activity was higher in the gastrointestinal tract of DEB 700 group when compared to the DEB 200 group. DEB 700 group had lower routine metabolic (RMR) and standard metabolic (SMR) rates, indicating a decrease in maintenance energy expenditure 48h after feeding the alkaline diet. The current study demonstrates that feeding meagre with an alkaline diet not only causes acid-base imbalance, but also negatively affects digestion and possibly nutrient assimilation, resulting in decreased growth performance.
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; IIB-INTECH (CONICET), Chascomús, Argentina. Electronic address: lmagnoni@ciimar.up.pt.
Leonardo J
LJ
Magnoni
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; IFAPA Centro "El Toruño" Consejería de Agricultura, Pesca y Desarrollo Rural, Junta de Andalucía, Apartado 16, El Puerto de Santa María, 11500 Cádiz, Spain.
Emilio
E
Salas-Leiton
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal.
Maria-João
MJ
Peixoto
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal.
Luis
L
Pereira
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal.
Francisca
F
Silva-Brito
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal.
Filipa
F
Fontinha
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal.
José F M
JFM
Gonçalves
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal; Wilfrid Laurier University, Waterloo, Canada.
Jonathan M
JM
Wilson
Aquaculture and Fisheries Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University, 6700 AH Wageningen, The Netherlands.
Johan W
JW
Schrama
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal.
Rodrigo O A
ROA
Ozório
D000681:Amylases / Q000378:metabolism*; D000821:Animal Feed; D000818:Animals; D004032:Diet; D004573:Electrolytes / Q000008:administration & dosage*; D004734:Energy Metabolism / Q000502:physiology*; D005753:Gastric Mucosa / Q000378:metabolism; D010473:Perciformes / Q000254:growth & development* / Q000378:metabolism*; D014882:Water-Electrolyte Balance
D004573:Electrolytes; D000681:Amylases
Acid-base balance; Dietary cation-anion difference; Digestion; Energy use; Euryhaline fish