Study objectives were to determine the magnitude of feed restriction (FR), which causes “leaky gut” and characterize the temporal consequences on production and blood variables. Twenty-three lactating Holstein cows (157 ± 46 DIM; 713 ± 54 kg BW; parity 2–4) were enrolled in 2 experimental periods. Period 1 lasted 5 d (ad libitum feed intake) and served as baseline for period 2 (P2), which lasted 5 d during which cows received one of 5 dietary treatments: 100% of ad libitum feed intake (AL; n = 3), 80% of ad libitum feed intake (AL80; n = 5), 60% of ad libitum feed intake (AL60; n = 5), 40% of ad libitum feed intake (AL40; n = 5), or 20% of ad libitum feed intake (AL20; n = 5). As the magnitude of FR increased, milk yield, MUN, and milk lactose content decreased linearly (P < 0.01) whereas milk fat content linearly increased (P = 0.02). Heart rate declined linearly with increasing FR (P < 0.02) while respiration rate declined similarly for all FR treatments (P = 0.02). Body weight loss increased linearly with increased FR (P < 0.01). Both plasma insulin and BUN decreased, whereas NEFA increased linearly with greater FR (P < 0.01). Lipopolysaccharide binding protein, haptoglobin, and serum amyloid A tended to increase linearly with increasing FR (P = 0.09, P = 0.07, P = 0.10, respectively). Circulating lymphocytes increased with increasing FR (P = 0.04). AL40 and AL-fed cows were killed to determine the effect of FR on intestinal histology. Jejunum villus width, jejunum goblet cell area, ileum height and ileum crypt depth were or tended to be reduced (P = 0.03, 36%; P = 0.02, 52%; P = 0.06, 22%; P = 0.03, 28%, respectively) in AL40 cows compared with AL controls. Liver weight tended to be decreased (15%; P = 0.07) in AL40 compared with AL cows. Liver fat and moisture percentages did not differ between treatments. In summary, FR tended to increase circulating acute phase proteins, which we speculate is due to an increase in leaky gut as demonstrated by the deterioration in intestinal architecture. Consequently, FR appears to be a simple and viable model to study intestinal integrity and barrier function.