Wang J, Provenza F D
Department of Rangeland Resources, Utah State University, Logan 84322-5230, USA.
J Anim Sci. 1996 Oct;74(10):2349-54. doi: 10.2527/1996.74102349x.
Ruminants eat a variety of foods, varying in toxins and nutrients, but no hypotheses adequately explain this behavior. We offer an explanation, one which encompasses avoidance of toxins and acquisition of nutrients. A key concept in this hypothesis is aversion, the decrease in preference for food just eaten as a result of sensory input (taste, odor, texture, i.e., a food's flavor) and postingestive effects (of toxins and nutrients on chemo-, osmo-, and mechano-receptors) unique to each food. On the basis of this hypothesis, we predicted lambs would prefer familiar and novel foods that complemented the macronutrient composition of their basal diet. To assess the validity of this prediction, we fed 10 lambs in each of three treatments different levels of ground barley (high in energy) and alfalfa (high in protein) as a basal diet. We then offered them daily a meal of three ground foods differing in proportions of barley and alfalfa (familiar foods) or wheat and rabbit pellets (novel foods). We found that lambs fed a basal diet high in energy (barley) preferred food lower in energy and higher in protein (alfalfa); those fed a diet high in alfalfa preferred food high in barley (P < .01). In addition, the higher the barley or alfalfa content of the basal diet, the greater the acceptance of novel foods high in alfalfa (i.e., rabbit pellets) or grain (i.e., wheat), respectively (P < .01). All lambs preferred foods high in wheat to rabbit pellets or alfalfa (P < 0.01), evidently because wheat is high in energy and it differs in flavor from barley, which was eaten repeatedly as part of the basal diet. On the basis of these results, we contend that lambs preferred familiar and novel foods that complemented the flavors and macro-nutrient contents of their basal diet.
反刍动物食用各种食物，这些食物的毒素和营养成分各不相同，但尚无假说来充分解释这种行为。我们给出一种解释，它涵盖了对毒素的规避和营养物质的获取。该假说的一个关键概念是厌恶性，即由于每种食物特有的感官输入（味道、气味、质地，即食物的风味）和摄食后效应（毒素和营养物质对化学、渗透压和机械感受器的影响），导致对刚吃过的食物的偏好降低。基于这一假说，我们预测羔羊会更喜欢能补充其基础日粮宏量营养素组成的熟悉和新奇食物。为了评估这一预测的有效性，我们将10只羔羊分为三组，分别用不同水平的碎大麦（能量高）和苜蓿（蛋白质高）作为基础日粮进行饲养。然后，我们每天给它们提供一顿由三种碎食物组成的餐食，这三种食物的大麦和苜蓿比例不同（熟悉食物）或小麦和兔粮（新奇食物）。我们发现，以高能量（大麦）基础日粮饲养的羔羊更喜欢能量较低、蛋白质较高的食物（苜蓿）；以高苜蓿日粮饲养的羔羊则更喜欢大麦含量高的食物（P <.01）。此外，基础日粮中大麦或苜蓿的含量越高，对苜蓿含量高（即兔粮）或谷物含量高（即小麦）的新奇食物的接受度就分别越高（P <.01）。所有羔羊都更喜欢小麦含量高的食物，而不是兔粮或苜蓿（P < 0.01），显然是因为小麦能量高，且其风味与作为基础日粮一部分反复食用的大麦不同。基于这些结果，我们认为羔羊更喜欢能补充其基础日粮风味和宏量营养素含量的熟悉和新奇食物。
