Figure 1.

Experimental design. In vivo experiment: black line, adaptation, and recovery; green dotted line, normal high-protein diet feeding; red dotted line, normal low-protein diet feeding; red line, low-protein diet cross-feeding; green line, high-protein diet cross-feeding. Each sampling period lasted two days. In vitro fermentation: black line, continuous fermentation, and dense sampling for 48 h. Abbreviations: HP, high-protein diet treatment; LP, low-protein diet treatment; HP_fe + HP_il, high-protein diet treatment feces and high-protein diet treatment ileal digesta; LP_fe + HP_il, low-protein diet treatment feces and high-protein diet treatment ileal digesta; HP_fe + LP_il, high-protein diet treatment feces and low-protein diet treatment ileal digesta; LP_fe + LP_il, low-protein diet treatment feces and low-protein diet treatment ileal digesta.