The giant reed has a rather poor nutritive value and its use for forage is limited. However, ruminants have been used with variable success in attempts to control its invasiveness (Daar, 1983; USDA, 2012).
Giant reed forage has limited palatability to ruminants. Younger plants (50-100 cm height) are more palatable and of better nutritive value than older plants (Shehata et al., 2006). Giant reed silage is as palatable as maize silage, and is better consumed than the giant reed hay or berseem hay (Ahmed et al., 2011b; Shehata et al., 2006).
Due to its high fibre and low protein content, Arundo donax foliage is poorly digested. Reported values from Egypt were about 47-51% (Tagel-Din, 1990) and 50-52% (Ahmed et al., 2011b) for DM digestibility, and about 54-56% for OM digestibility (Ahmed et al., 2011b). However, a higher DM digestibility of 69% was reported in an early trial in India (Talapatra, 1950). Several trials in Egypt have studied the value of the giant reed, either ensiled or fresh. Fresh giant reed forage and giant reed silage (ensiled with 3% molasses on a fresh weight basis) were better digested by Rahmani sheep than giant reed hay or berseem hay (Ahmed et al., 2011b; Shehata et al., 2006). This can be explained by a higher microbial activity in the rumen with fresh or ensiled forages compared to the hays: total volatile fatty acid concentration and microbial protein production were higher 4 h after feeding (Ahmed et al., 2011b). Giant reed silage was found as digestible as maize silage (Abo-Donia et al., 2009; Shehata et al., 2006).
At the time of writing (2014), trials on the utilization of Arundo donax in cattle have only concerned its veterinary properties. All trials took place in India. Arundo donax extracts had anthelmintic properties (around 55% of efficacy) against gastrointestinal parasites (Ascaris sp., Oesophagostomum sp. and Paramphistomum sp.) in cattle (Sharatkumar et al., 2004). A commercial bolus made of a mixture of several powdered plants including Arundo donax improved milk yield in dairy cows, which was attributed to the presence of components reported to be galactogogues (Baig et al., 2009; Behera et al., 2013).
In Egyptian lambs, ensiled and fresh giant reed forage gave better fattening performance than giant reed hay, the latter being close to berseem hay in that respect (Ahmed et al., 2009). Dressing values, carcass weight and more generally carcass quality (shoulder and leg cuts) were significantly improved with silage or fresh giant reed compared to berseem hay and giant reed hay (Ahmed et al., 2011a). Blood parameters were similar for all the treatments, except red blood cells which were higher for the fresh or ensiled reeds (Ahmed et al., 2009). Giant reed silage had no adverse effects when fed with whole dates and olive cake in order to solve the shortage of green fodder in Egyptian oases (Shwerab et al., 2010).
In Egyptian Rahmani rams, giant reed silage gave a better reproductive performance than fresh reeds and reed hay, and the results obtained were closed to those observed with berseem hay (Ahmed et al., 2009).
In Egypt, giant reed silage or fresh forage fed to Zaraibi goats gave higher milk yields than giant reed hay. The milk composition did not differ between diets (Ahmed et al., 2011b; Shehata et al., 2006).