Sánchez-Vázquez F J, Yamamoto T, Akiyama T, Madrid J A, Tabata M
Department of Physiology and Pharmacology, Faculty of Biology, University of Murcia, Spain.
Physiol Behav. 1998 Nov 15;65(2):211-8. doi: 10.1016/s0031-9384(98)00047-x.
In the wild, both food availability and an animal's requirements may fluctuate. Given the choice to feed on different diets, animals may exhibit preferences in their selection. Although macronutrient selection has been investigated in mammals and birds, few attempts have been made to investigate dietary selection in fish. In the present study we investigate the feeding of goldfish on three "pure" macronutrient diets. Twelve single goldfish and one group of four goldfish, initially weighing 163.1 +/- 7.4 and 70.2 +/- 8.0 g, respectively, were maintained in 54-liter tanks at 20 degrees C under a 12 h:12 h light-dark (LD) cycle. Three pelleted diets were made containing 50% of each macronutrient: protein (casein + gelatin), fat (fish oil + soy oil), or carbohydrate (dextrin). All the diets included mixtures of vitamins and minerals, a binder (sodium alginate), and cellulose as a filler. During trials, three self-feeding devices delivering the protein, fat, or carbohydrate diet were installed in each aquarium. Goldfish soon learned to select from among the three diets. Overall daily food and digestible energy demands differed significantly between macronutrients. The demand for protein was lower than that for carbohydrate (16.6 and 33.7 g/kg BW/day, respectively), and the digestible energy demand for protein was lower than for fat (108.6 and 308.5 kJ/kg BW/day, respectively). Goldfish made their dietary selections on the basis of energy content, so that food demand increased to compensate for changes in the digestible energy density of the diets. Correlation analysis revealed a significant positive relationship between carbohydrate and fat demand (n = 8), whereas there were significant negative (n = 3) and positive (n = 1) relationships between protein and fat. Different daily patterns for the selection of each macronutrient were detected in some fish (i.e., carbohydrate during daytime, protein at the beginning of the night, and fat during the transition phase). In short, our results demonstrated the ability of goldfish to compose their own diet from three basic macronutrients, highlighting the complex pattern of behavior in their selection. Therefore, these new findings should be considered when studying feeding rhythms and the design of diets for fish.
在自然环境中，食物的可获得性和动物的需求都可能波动。当可以选择不同的食物时，动物在选择上可能会表现出偏好。虽然在哺乳动物和鸟类中已经对常量营养素的选择进行了研究，但很少有人尝试研究鱼类的饮食选择。在本研究中，我们调查了金鱼对三种“纯”常量营养素饲料的摄食情况。将12条单尾金鱼和一组4条金鱼（初始体重分别为163.1±7.4克和70.2±8.0克）饲养在54升的水族箱中，温度为20摄氏度，光照周期为12小时光照：12小时黑暗（LD）。制作了三种颗粒饲料，每种常量营养素各占50%：蛋白质（酪蛋白+明胶）、脂肪（鱼油+大豆油）或碳水化合物（糊精）。所有饲料都包含维生素和矿物质的混合物、一种粘合剂（海藻酸钠）以及作为填充剂的纤维素。在试验期间，在每个水族箱中安装了三个分别投喂蛋白质、脂肪或碳水化合物饲料的自动投喂装置。金鱼很快就学会了从这三种饲料中进行选择。不同常量营养素的每日食物和可消化能量总需求量存在显著差异。蛋白质的需求量低于碳水化合物（分别为16.6和33.7克/千克体重/天），蛋白质的可消化能量需求量低于脂肪（分别为108.6和308.5千焦/千克体重/天）。金鱼根据能量含量进行饮食选择，因此食物需求量会增加以补偿饲料可消化能量密度的变化。相关分析显示碳水化合物和脂肪需求量之间存在显著正相关（n = 8），而蛋白质和脂肪之间存在显著负相关（n = 3）和正相关（n = 1）。在一些鱼中检测到了每种常量营养素选择的不同每日模式（即白天选择碳水化合物，夜间开始时选择蛋白质，过渡阶段选择脂肪）。简而言之，我们的结果证明了金鱼能够从三种基本常量营养素中自行组成饮食，突出了它们选择行为的复杂模式。因此，在研究鱼类的摄食节律和饲料设计时应考虑这些新发现。
