Impact of feed restriction duration on gastrointestinal fermentation, histomorphology, transcript abundance, and splanchnic tissue weight in lambs.

This study evaluated the effects of 5 or 10 d of feed restriction (FR) on gastrointestinal fermentation, splanchnic tissue weights and histomorphology, and the abundance of transcripts for genes involved in absorptive and barrier functions. Twelve rams and nine wethers were blocked by castration status and BW in a randomized complete block design. Lambs were assigned to ad libitum feeding (CON; n = 7) or to FR at 30% of ad libitum for 5 (FR5; n = 7) or 10 d (FR10; n = 7). Body weight (P = 0.032) and reticulo-ruminal SCFA concentrations decreased quadratically, while cecal SCFA decreased linearly (P = 0.036). Ruminal, abomasal, jejunal, and colonic tissue weights decreased quadratically (P ≤ 0.026), while omasal, duodenal, and ileal tissue weights decreased linearly (P ≤ 0.026). Liver weight decreased quadratically (P = 0.002). Ruminal papillae effective surface area declined linearly (P = 0.035). Transcript expression for SGLT1, GLUT2, MCT1, and ZO1-TJP1 in the ileum decreased linearly (P ≤ 0.036), while expression in the rumen was unaffected. The results suggest that the reduction in nutrient intake imposed with FR induces acute decreases in splanchnic tissue weights with most of the changes occurring within the first 5 d.