Study objectives were to determine a magnitude of feed restriction which causes “leaky gut” and characterize its temporal consequences on production and blood parameters. Twenty-three lactating Holstein cows (157 ± 46 DIM; 713 ± 54 kg BW; parity 2-4) were enrolled in two experimental periods. Period 1 lasted 5 d and served as baseline for period 2 (P2), which lasted 5 d during which cows received one of five 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 (n=5), 40% of ad libitum feed intake (AL40; n=5), or 20% of ad libitum feed intake (n=5). As feed restriction increased, milk yield and milk urea nitrogen, lactose, and other solids decreased linearly (P