Influence of dietary flavours on sheep feeding behaviour and nutrient digestibility

The aim of the present study was to assess whether the feeding pattern displayed by sheep exposed to a monotonous ration is modified when the same ration is presented in a diversity of flavours and if such diversity influences nutrient intake and digestibility. Twelve commercial crossbred wether lambs were assigned to two groups. Six lambs/period (three lambs/group.period) were housed in metabolic crates during two successive periods. One group of lambs (Diversity, D) was fed simultaneously an unflavoured ration of alfalfa, barley, beet pulp and urea (55:35:9:1) and the same ration supplemented (0.2%) with one of the following two flavours: (1) sweet, and (2) umami. The other group (Monotony, M) received only the unflavoured ration. All animals were fed their respective rations ad libitum from 0800 hours to 1600 hours for 26 days in each period. Day 19 was used for assessing the lamb feeding pattern every 30 min for 8 h, and the last 6 days of the period were used for estimating in vivo food digestibility. Lambs in D tended to ingest more acid detergent fibre (ADF; P = 0.10) and to have a lower crude protein digestibility (P = 0.08) than did lambs in M. Nevertheless, average daily DM intake did not differ between treatments (P = 0.22) and lambs in M and D digested the same amount of DM, neutral detergent fibre, ADF and N (P > 0.10). Flavour diversity did not affect N retained, N retained/N consumed, or ruminal pH 1 h after feeding (P > 0.10). Lambs in D showed greater intakes than did those in M during 30 (P = 0.006), 60 (P = 0.02), 90 (P = 0.02), 120 (P = 0.04) and 180 min (P = 0.07) after offering the rations. Results suggest that changes in eating behaviour occurred only during the first part of the feeding period, leading to slight changes in ADF intake and crude protein digestibility, which did not impact nutrient utilisation.