FOOD FLAVOR AND NUTRITIONAL CHARACTERISTICS ALTER DYNAMICS OF FOOD PREFERENCE IN LAMBS

We addressed two questions involving food preference. First, we determ ined how a food's flavor and nutritional. characteristics affected pre ference. In three trials, we offered lambs isonitrogenous foods differ ing in energy (trial 1, 90% TDN; trial 2, 100% TDN; trial 3, 110% TDN) ; each food was offered in apple and maple flavors. We hypothesized th at preference for apple-or maple-flavored food would decrease with inc reasing duration of exposure (1, 2, or 4 d), and we speculated that ri se change in preference would intensify when food contained inadequate or excessive levels of energy. After eating food in one flavor, lambs preferred the alternative flavor, even after only a 1-d exposure, and preference for the alternative flavor was greater when the food had i nadequate or excessive energy (P <.05). The second experiment determin ed whether eating a food with rapidly or slowly digestible sources of energy in the morning affected lambs' food preferences in the evening. We speculated that lambs fed rapidly-digestible food in the morning m ay prefer a slowly digestible food in the afternoon because slowly dig estible food better maintains nutrient status throughout the night or because preference for the rapidly digestible food decreases after exp osure in the morning. We offered lambs isonitrogenous and isocaloric f oods, that differed in rates of digestion, in apple and maple flavors. Lambs fed rapidly digestible food in the morning preferred slowly dig estible food in the alternative flavor in the evening. However, lambs fed slowly digestible food in either flavor in the morning preferred s lowly digestible food in both flavors in the evening (P <.05). These r esults show that lambs' preferences change as a result of food ingesti on, and the degree of change in preference depends on the nutritional characteristics of the food. These findings further suggest food intak e might be increased by providing a variety of foods to livestock on r angelands, pastures, or in confinement.