Ackroff K, Schwartz D, Collier G
Physiol Behav. 1986;38(1):71-80. doi: 10.1016/0031-9384(86)90134-4.
Rats were studied in a laboratory simulation of foraging for separate sources of carbohydrate, fat, and protein. Fixed ratios of bar-presses were required to search for a cue signalling the availability of a meal and to procure each meal. In the first phase, the costs of procuring all three foods were raised equally for three rats. Meal frequency declined and meal size increased for all three foods. Protein opportunities were accepted more frequently than those for other foods, and the proportion of calories taken from protein remained low and constant. Two rats were studied in the remaining three phases. When protein meal cost was raised while the costs of energy foods were low, protein intake was gradually reduced and at the highest cost was dropped from the diet. There were individual differences in the preferred source of energy calories; when each animal's preferred energy source was made more costly, these preferences persisted over the range of costs studied in one rat, but shifted abruptly in the other rat. Finally, when search costs were raised, the animals became less selective in accepting meal opportunities and composing their diets. These results suggest that diet selection in the rat is flexible and responsive to changes in the costs of acquiring food. This ability is consistent with the foraging behaviors required by omnivorous generalized feeders.
在实验室模拟大鼠觅食碳水化合物、脂肪和蛋白质不同来源食物的过程中，研究人员进行了相关实验。大鼠需要按照固定的压杆比率来寻找提示进食机会的信号并获取每餐食物。在第一阶段，提高了三只大鼠获取所有三种食物的成本。所有三种食物的进食频率下降，进食量增加。与其他食物相比，大鼠更频繁地选择蛋白质类食物，但从蛋白质中摄取的卡路里比例仍保持在较低且稳定的水平。在剩下的三个阶段对另外两只大鼠进行了研究。当提高蛋白质类食物的成本而能量类食物成本较低时，蛋白质摄入量逐渐减少，在成本最高时从饮食中剔除。在能量卡路里的偏好来源方面存在个体差异；当提高每只动物偏好的能量来源的成本时，在一只大鼠研究的成本范围内这些偏好持续存在，但在另一只大鼠中则突然改变。最后，当提高搜索成本时，动物在接受进食机会和组成饮食时变得不那么挑剔。这些结果表明，大鼠的饮食选择具有灵活性，并且会对获取食物成本的变化做出反应。这种能力与杂食性广食者所需的觅食行为一致。
