FOOD-DEPRIVATION AFFECTS PREFERENCE OF SHEEP FOR FOODS VARYING IN NUTRIENTS AND A TOXIN

We investigated how food deprivation affected preference of lambs for foods that varied in concentrations of nutrients and a toxin. Thirty l ambs (10 lambs/treatment) were fed different amounts of alfalfa pellet s (high in protein, marginal in energy for growth) as a basal ration ( 20, 40, or 60 g/kg body weight). Every morning, prior to ingesting the basal ration of alfalfa pellets, each lamb was offerend three foods f or 15 min. The foods contained different amounts of energy and a toxin , depending on the addition of barley (energy) and LiCl (toxin) to alf alfa. The proportions of barley and LiCl changed every five days durin g the 25-day study. The results showed: (1) all lambs preferred food t hat was high > intermediate > low in energy (barley) in the absence of LiCl, but all lambs decreased consumption of foods high in energy as LiCl concentrations increased; (2) the greater the level of food depri vation, the Lower the consumption of foods containing LiCl, even if th e foods provided high levels of energy; (3) lambs moderately food depr ived or fed ad libitum ingested more LiCl than lambs that were highly deprived; and (4) lambs quickly (15 min/day) regulated intake of foods in response to changes in barley and LiCl concentrations. Thus, our r esults suggest that the interaction between nutritional status and tox icosis plays an important role in food preference of lambs. Our findin gs also suggest that toxic plants may kill herbivores that lack nutrit ious alternative foods not only because the animals are forced to be l ess discriminating, but also because they are more susceptible to toxi ns.