Intake and digestibility of reed (Phragmites australis) silage and mixed grass haylage in Icelandic horses

Common reed (Phragmites australis) is a stand forming macrophyte with potential to be utilised as a roughage for horses. Data on intake and feed value in horses is scarce for reed and a feeding trial was therefore conducted. Icelandic horses were fed reed silage and grass haylage in a cross over study. Feed and water intake was measured, and total collection of faeces and urine performed to evaluate apparent total tract digestibilities and energy, nitrogen and water balance. Horses consumed less reed silage (82 % of the offered amount of dry matter (DM)) and at a slower rate (114 min/kg DM) compared to grass haylage (100 % of offered DM amount, 41 min/kg DM), and two horses refused the reed silage. Horses selected parts of the reed silage (but not grass haylage) for consumption, and reed silage refusals had lower crude protein (CP) and higher neutral detergent fibre (NDF) concentrations compared to the reed silage as fed. Apparent total tract digestibility was 50 and 57 % for dry matter, 69 and 72 % for CP, and 57 and 58 % for NDF for reed silage and grass haylage respectively, with no differences between the diets. Water balance and gross energy digestibility was similar between the diets, while N balance was closer to zero when horses were fed reed silage compared to grass haylage. The results suggest that reed silage could be a useful roughage for horses that have comparably low energy requirements, if they do not refuse to eat it.