In vivo nutrient digestibility. Apparent ileal digestibility (A) and apparent total tract digestibility (B) of nutrients. Values are the means of 6 observations per treatment. * Significant difference compared with HP + HPD treatment (p ≤ 0.05); ** significant difference compared with HP + HPD treatment (p ≤ 0.01). Values are the least squares means ± SD; n = 6. Green bar, high-protein diet treatment; red bar, low-protein diet treatment. Abbreviations: HP, high-protein diet treatment; LP, low-protein diet treatment; HPD, high-protein diet feeding; LPD, low-protein diet feeding; AID, apparent ileal digestibility; ATTD, apparent total tract digestibility; DM, dry matter; OM, organic matter; CP, crude protein; GE, gross energy; NDF, neutral detergent fiber; ADF, acid detergent fiber.