The effect of forage theoretical cut lengths on chewing activity, rumen fermentation, dissolved gases, and methane emissions in goats

•Forage theoretical cut length alters particle size distribution and influences chewing activity.•Forage theoretical cut lengths do not alter rumen fermentation and nutrient digestibility.•Forage theoretical cut lengths marginally decrease saturation factor of hydrogen.•Increased chewing activity is not accompanied with the reduction in ruminal dissolved gases.•Increased chewing activity is not accompanied with a change in methane emissions.