PS8-27. Long-term Impact of a High-starch Diet Early in Life on Feeding Behavior and Rumination in Sheep.

Abstract We aimed to determine the long-term effects of a high-starch diet early in life on feeding behavior and rumination in individually housed sheep. Fifty-four male lambs (5-15 days of age; 3 batches) were randomly divided into a high-fiber (HF) and a high-starch (HS) group, kept in eight group pens (6-7 animals/pen; 4 pens/treatment). They were fed ad libitum milk replacer (MR) and either a meadow and alfalfa hay mixture (1:1; HF; n = 27) or a concentrate mixture (70% barley, 15% wheat bran, 10% soybean meal, 5% chopped hay; HS; n = 27). The MR was provided for 7 weeks and experimental solid feeds were fed for additional 2 weeks after weaning (Phase 1; P1). Subsequently, all lambs were transitioned to a hay-based diet and fed ad libitum until 7.8 months of age (Phase 2; P2), and then were challenged with a high-starch diet (Phase 3; P3). Challenge was induced by replacing 50% of dry matter consumed as hay with barley. At the end of each phase, a subset of randomly selected animals per treatment (8 to 10; depending on phase) was placed in individual pens, and behavior was monitored using continuous video recordings. Data were analyzed using a mixed model procedure in SAS. The statistical model included the fixed effect of treatment and random effects of animal batch and group pen within a batch. During P1, HS spent more time being inactive (730 vs. 442 min/day; P < 0.01) and less time eating (234 vs. 393 min/day; P < 0.01) compared to HF. Furthermore, the HS showed faster eating rate (3.31 vs. 1.49 g DM/min; P < 0.01), spent less time ruminating (197 vs. 441 min/day; P < 0.01), and spent more time performing atypical behaviors (92.4 vs. 17.2 min/day; P < 0.01). In P2, despite consuming the same hay-based diet, HS spent less time eating (300 vs. 358 min/day; P < 0.01) and demonstrated a faster eating rate (4.36 vs. 3.43 g DM/min; P < 0.01). They also spent more time being inactive (P = 0.05); however rumination time and atypical behaviors did not differ between treatments. During P3, the HS still showed a faster eating rate (7.07 vs. 5.01 g DM/min; P < 0.01) and shorter eating time (154 vs. 194 min/day; P = 0.04). They spent more time ruminating (380 vs. 276 min/day; P = 0.03) and tended to perform more atypical behaviors (P = 0.10). However, rumination rate (min/g DM) did not differ between groups. In conclusion, early-life exposure to a high-starch diet programmed persistently higher eating rates in sheep, without long-term impacts on rumination. This research was funded by the National Science Centre, Poland, under the OPUS call in the Weave program (project No. 2021/43/I/NZ9/02222).