Effect of Potato By-products Based Silage on Rumen Fermentation, Methane Production and Nitrogen Utilization in Holstein Steers

The effect of substituting potato by-products based silage (PBS) for concentrates on ruminal fermentation, methane production and nitrogen utilization in Holstein steers was evaluated. Three growing Holstein steers ($490{\pm}19kg$, initial body weight) were used in a $3{\times}3$ Latin square experiment with three experimental diets in which PBS was included at (1) 0, (2) 19 and (3) 27%, on a dry matter basis, replacing concentrates and wheat bran. Increasing replacement levels of PBS slightly increased dry matter (DM), organic matter (OM), NDF and ADF intakes by the steers (p<0.05). Inclusion of PBS at 19% increased crude protein (CP) digestibility of the experimental diets compared with the control (p<0.05). Substitution with PBS increased ADF digestibility and nitrogen retention (p<0.05), but did not affect energy retention. Energy loss as methane ranged between 5.0 and 6.1% of the total gross energy intake. There were no significant differences in carbon dioxide and methane production among all PBS levels, while daily methane production numerically increased with PBS inclusion. Substituting PBS for concentrates did not significantly affect ruminal pH and ammonia N concentration. Total VFA concentration, VFA molar proportions and blood metabolites were also unaffected by PBS replacement. These results suggest that substitution of PBS up to 27% of diet dry matter did not significantly increase methane production and was equal or superior to concentrates in ADF digestibility and nitrogen retention for growing steers.