Feeding behavior and performance of lambs are influenced by flavor diversity.

This study determined whether early experiences by sheep to the same feed, but presented in multiple or single flavors influence intake, 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 (Diversity) were fed simultaneously an unflavored control - plain ration of alfalfa and barley (75:25) and the same ration mixed (0.2%) with 1 of 3 flavors: (1) sweet, (2) umami, and (3) bitter. The other 4 treatments (Monotonous diets) received just 1 of the four rations. All animals were fed their respective rations from 0800 to 1600 for 60 d. On d 55, intake was recorded every 30 min for 8 h. On day 58 lambs were bled 1 h pre-feeding and at 30, 60, 210, 300, and 540 min post-feeding. Preference tests were conducted by offering simultaneously novel feeds of either (1) high-energy, (2) high-protein content, (3) beet pulp mixed with phytochemicals, or (4) low-quality feeds. Lambs in Diversity consumed more feed than lambs in the other treatments (P < 0.001). Lambs in Diversity consumed equivalent amounts of Plain and Umami feeds, with Umami being consumed at a greater level (P < 0.001) than the Bitter and Sweet feeds. Lambs in Diversity tended to grow faster than lambs in the other treatments (P = 0.06). On d 55, lambs in Diversity showed lower (P < 0.05) intakes than the other treatments during the 2 peaks of food consumption: 30 min and 270 min from feeding, and a trend for the lowest plasmatic concentrations of ghrelin (P = 0.06). In contrast, lambs in Diversity consumed more feed than lambs exposed to monotonous flavors at 60, 90, 120, and 180 min from feeding (P < 0.05). Lambs in Diversity also showed the lowest concentration of CCK and GLP-1 (P < 0.001). There was a trend for the greatest concentration of leptin (P = 0.14) and IGF-1 (P = 0.16) in Diversity, and for the lowest concentration of leptin in Bitter (P = 0.14). Previous experience with flavored feeds affected preference for high-energy and low-quality feeds, and for beet pulp mixed with phytochemicals (treatment x feed x 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 initial acceptability and preference for novel feeds.