The potential of chemically treated common reed (Phragmites australis) hay in maintenance diets for sheep. 1. The effect of NaOH treatment and ensilage with urea on intake, digestibility and rumen kinetics.

Untreated, NaOH treated and urea ensiled common reed hay were evaluated in a digestion study with sheep. The hemicellulose fraction was partially solubilized by both chemical treatments, while the lignin fraction was apparently not affected. NaOH treatment increased digestibility and organic matter  intake by 12 and 130% respectively, while urea ensilage had no significant effect in this regard. Although not significant, NaOH treatment tended to increase the mass of organic matter in the rumen. It also resulted in a highly significant decrease of 30% in the retention time of non-fermentable organic matter in the rumen. Although the delay constant of fermentation was increased by NaOH treatment it was counterbalanced by an increase in the lag constant for fermentation so that the in sacco retention time for fermentation did not differ significantly from that of the control treatment. Urea ensilage had no significant effect on any of these rumen parameters. NaOH treatment also resulted in a 35% decrease in rumen ammonia concentration and an increase of 73% in the total volatile fatty acid concentration. Urea ensilage resulted in an increase of 60% in rumen ammonia concentration but had no significant effect on total volatile fatty acid concentration. Rumen pH and the ratio of volatile fatty acids in the rumen were not effected by chemical treatment.