J. Wang et Fd. Provenza, FOOD PREFERENCE AND ACCEPTANCE OF NOVEL FOODS BY LAMBS DEPEND ON THE COMPOSITION OF THE BASAL DIET, Journal of animal science, 74(10), 1996, pp. 2349-2354
Ruminants eat a variety of foods, varying in toxins and nutrients, but
no hypotheses adequately explain this behavior. We offer an explanati
on, one which encompasses avoidance of toxins and acquisition of nutri
ents. A key concept in this hypothesis is aversion, the decrease in pr
eference 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 prefe
r familiar and novel foods that complemented the macro-nutrient compos
ition 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 rabbi
t 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 barl
ey (P < .01). In addition, the higher the barley or alfalfa content of
the basal diet, the greater the acceptance of novel foods high in alf
alfa (i.e., rabbit pellets) or grain (i.e., wheat), respectively (P <
.01). All lambs preferred foods high in wheat to rabbit pellets or alf
alfa (P < 0.01), evidently because wheat is high in energy and it diff
ers in flavor from barley, which was eaten repeatedly as part of the b
asal diet. On the basis of these results, we contend that lambs prefer
red familiar and novel foods that complemented the flavors and macro-n
utrient contents of their basal diet.