Feeding behavior and performance of lambs are influenced by flavor diversity1,2

Abstract

This study determined whether early experiences of sheep with the same feed, but presented in multiple or single flavors, would influence intake, the profile of hormones involved in feed intake regulation, and the subsequent acceptability of novel feeds. Thirty-five 2-mo-old lambs were randomly assigned to 5 treatments (7 lambs/treatment). Lambs in 1 treatment (the diversity treatment) were simultaneously fed an unflavored plain ration of alfalfa (control) and barley (75:25; as-fed basis) and the same ration mixed (0.2%) with 1 of 3 flavors: 1) sweet, 2) umami, or 3) bitter. The other 4 treatments (monotonous diets) received only 1 of the 4 rations. All animals were fed their respective rations from 0800 to 1600 h for 60 d. On d 55, intake was recorded every 30 min for 8 h. On d 58, blood samples from lambs were collected at 1 h prefeeding and at 30, 60, 210, 300, and 540 min postfeeding. Preference tests were conducted by simultaneously offering novel feeds: 1) high-energy feed, 2) high-protein feed, 3) beet pulp mixed with phytochemicals, or 4) low-quality feed. Lambs in the diversity treatment consumed more feed than did lambs in the other treatments (P < 0.001). Lambs in the diversity treatment consumed equivalent amounts of plain and umami feeds, with a greater amount (P < 0.001) of the umami feed being consumed than the bitter and sweet feeds. Lambs in the diversity treatment tended to grow faster than did lambs in the other treatments (P=0.06). On d 55, lambs in the diversity treatment showed decreased (P < 0.05) feed intake compared with lambs in the other treatments during the 2 peaks of food consumption (30 and 270 min from feeding) and showed a trend for the least plasma concentrations of ghrelin (P=0.06). In contrast, lambs in the diversity treatment consumed more feed than did lambs exposed to monotonous flavors at 60, 90, 120, and 180 min from feeding (P < 0.05). Lambs in the diversity treatment also showed the least concentrations of cholecystokinin and glucagon-like peptide 1 (P < 0.001). There were trends for the greatest concentrations of leptin (P=0.14) and IGF-1 (P=0.16) in the diversity treatment, and for the least concentration of leptin in the bitter treatment (P=0.14). Previous experience with flavored feeds affected the preference of lambs for high-energy and low-quality feeds, and for beet pulp mixed with phytochemicals (treatment × feed × day effect; P < 0.05). Thus, exposure to diverse flavors has the potential to increase feed intake and induce a more even consumption of feed across time by reducing peaks and nadirs of intake compared with exposure to monotonous rations. Flavor diversity may also influence the initial acceptability of and preference for novel feeds.