Magnoni Leonardo J, Salas-Leiton Emilio, Peixoto Maria-João, Pereira Luis, Silva-Brito Francisca, Fontinha Filipa, Gonçalves José F M, Wilson Jonathan M, Schrama Johan W, Ozório Rodrigo O A
CIIMAR, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; IIB-INTECH (CONICET), Chascomús, Argentina.
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.
Comp Biochem Physiol B Biochem Mol Biol. 2017 Sep;211:8-15. doi: 10.1016/j.cbpb.2017.03.001. Epub 2017 Mar 16.
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 NaCO content 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.
已知膳食离子含量会改变淡水鱼的酸碱平衡。本研究调查了广盐性物种灰鳍鲳（Argyrosomus regius）中，膳食电解质平衡（DEB）差异所产生的酸碱紊乱对代谢的影响。对随意采食两种实验日粮（NaCO含量不同，分别为DEB 200或DEB 700mEq/kg）69天的灰鳍鲳，分析其生长性能、胃内容物特征、血液pH值和离子浓度、消化酶活性及代谢率的变化。采食DEB 200日粮的鱼生长性能比DEB 700组好60 - 66%。采食DEB 200日粮的灰鳍鲳在将饲料能量分配到体生长方面比采食DEB 700日粮的鱼效率高90 - 96%。与DEB 200组相比，DEB 700组在喂食后2小时血液pH值显著更低，表明灰鳍鲳的酸碱平衡受日粮电解质平衡影响。血浆渗透压以及Na和K浓度不受日粮处理影响。DEB 700组胃内容物的pH值、干物质、蛋白质和能量含量更高，但脂质含量低于DEB 200组。喂食后24小时，DEB 700组胃肠道中的淀粉酶活性高于DEB 200组。DEB 700组的常规代谢（RMR）和标准代谢（SMR）率较低，表明喂食碱性日粮48小时后维持能量消耗减少。本研究表明，用碱性日粮喂养灰鳍鲳不仅会导致酸碱失衡，还会对消化以及可能的营养吸收产生负面影响，从而导致生长性能下降。
