PREFERENCE FOR WHEAT-STRAW BY LAMBS CONDITIONED WITH INTRARUMINAL INFUSIONS OF STARCH

We hypothesized that feed preference depends on the interplay between flavour and postingestive effects, and we tested two predictions based on this hypothesis: (1) lambs acquire preferences for poorly nutritio us feeds paired with starch; and (2) preferences persist when starch i s no longer administered. Twenty lambs were randomly allocated to two groups and conditioned as follows: on odd-numbered days, lambs in grou p 1 received onion-flavoured wheat straw and lambs in group 2 received oregano-flavoured wheat straw. On even-numbered days, the flavours we re switched and starch (2.5-9.4 % of the digestible energy received/d) was infused into the rumen of all animals during straw consumption. F our periods of 8 d of conditioning were performed and on the 9th day o f each period all animals were offered a choice between onion- and ore gano-flavoured straw. After conditioning, starch administration was su spended and lambs were offered onion- and oregano-flavoured straw at w eekly intervals for 8 weeks (extinction). Lambs strongly preferred the flavoured straw paired with starch, and this preference persisted dur ing extinction. Thus, these results suggest that the postingestive eff ects of energy play an important role in the development of feed prefe rences of ruminants.