Description: The authors investigated the effect of feeding 2 percentage sodium-hydroxide-treated (as-fed basis) or 2 percentage formaldehyde-treated (crude protein basis) wheat to rumen-, duodenal- and ileocaecal-cannulated Holstein steers on rumen fermentation and ruminal and postruminal starch degradation. Feeding 2 kg/day wheat treated with sodium hydroxide (NaOH) or formaldehyde did not affect negatively the main parameters of rumen fermentation, i.e. pH, short-chain fatty acid (SCFA) production, and microbial activity. Fibre degradation in the rumen was significantly improved when NaOH-treated wheat was fed. The in vivo experiments demonstrated that feeding NaOH- and formaldehyde-treated wheat to steers significantly increased the amount of starch that reached the small intestine. The amount of starch that entered the duodenum increased by 57 percentage and 75 percentage when steers were fed NaOH- and formaldehyde-treated wheat compared to the control phase, respectively. This higher quantity of starch was digested and absorbed, which can provide an increased glucose supply to the animals