Jj. Villalba et Fd. Provenza, PREFERENCE FOR WHEAT-STRAW BY LAMBS CONDITIONED WITH INTRARUMINAL INFUSIONS OF STARCH, British Journal of Nutrition, 77(2), 1997, pp. 287-297
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.