Effect of previous exposure of sheep to monoterpene odors on intake of alfalfa pellets treated with camphor or α-pinene

Lambs were subjected to odors of two monoterpenes (camphor and α-pinene) that decreased intake in a previous study to determine if exposure during feeding modified their effects on subsequent intake. In two experiments, 36 ewe lambs were group-fed alfalfa pellets in enclosed portable buildings each morning for 56 d (phase 1). Camphor (25 g, Experiment 1) or α-pinene (50 ml, Experiment 2) was placed in feeders in a mesh-covered container immediately before feeding. In phase 2, lambs were individually fed alfalfa pellets for 20 min each morning for 10 d (5-d adaptation, 5-d collection). Treatments were sprayed on alfalfa pellets at levels representing the concentration of that chemical in tarbush (Flourensia cernua) or at 10-fold that concentration. No day by treatment interactions were detected for intake during adaptation or collection periods for either chemical (P > 0.05); therefore, data were pooled across day. Exposure to the volatile aroma for 56 d had no effect on intake during the subsequent 10-d interval for either monoterpene (P > 0.05). Moreover, intake during the collection period was not affected by treatment concentration (P > 0.05). Neither concentration of the terpene applied to alfalfa pellets nor previous exposure to the volatile aroma of camphor or α-pinene altered feed intake under the conditions of this study.