Stover from corn and rice straw can both be used for livestock feed, but there are tradeoffs (per usual). This is especially true for rice straw which is not recommended for ruminant feeding without supplementing the diet.
Rice straw has less lignin than other post-harvest grain residues, but it also has higher silica and oxalate (1-2% DM) content. Silica is soluble and are largely excreted by livestock, but decreases the digestibility of the straw. Oxalates can decrease Ca concentration and therefore livestock absorption because it binds the Ca. Therefore Ca may need to be supplemented (especially for ruminants for which Ca is vital).
You can see the nutritional breakdown of rice straw as well as recommendations for supplements needed when feeding rice straw here.
In general, for either feedstock, harvesting and storing conditions (if you are storing it to feed later) greatly impact the feed quality of the material. The greener you can harvest it, the greater the nutritional value. As it dries down after grain harvest, annual grass residues decrease in nutritional content. And you want to store it in a place that is out of direct sunlight, does not get wet, and use it as soon as possible.
Maize stovers (stalks) have higher concentrations of P, Cu, Zn, Ca, and NaCl than rice straw as well as greater energy content and they tend to be more palatable. Farmers all around the world utilize this abundant feed source (primarily for ruminants)! It has high protein and energy content, but is very fibrous so it’s recommended to either supplement feed or process it. There is great information on this page including a nutrient composition table.