Lactational performance, nutrient digestibility and fermentation characteristics of Holstein dairy cows in response to feeding wheat factory sewage

The objective of this study was to evaluate whether wheat factory sewage (WFS) could partially replace barley grain in the diet of dairy cows without adversely affecting dry matter intake (DMI), ruminal fermentation, digestibility and milk production of dairy cows. Eight multiparous (60 ± 3 days-in-milk) Holstein dairy cows were used in a replicated 4 × 4 Latin square design experiment with four 21-d periods. The four diets (treatment) differed by partially substituting WFS for barley grain at the rate of 0% (WFS0), 4% (WFS4), 6% (WFS6) or 8% of dietary dry matter (DM; WFS8). DM content of diets decreased from 65%, 59%, and 57% to 54% by increasing the inclusion of WFS due to high water content of WFS (80%). DMI changed quadratically and tended (P = 0.08) to be higher for WFS4 (23.1 kg/d) than for other three diets which were similar (21.5 kg/d). Ruminal fluid pH linearly increased (P = 0.01) with increasing WFS in the diet. Ruminal concentrations of total volatile fatty acid (VFA; 100–103 mM), acetate (6...