I can't say as I have the numbers for livestock production either, but I do agree that biofuel serves more of a purpose than livestock because it can be used for purposes that you have mentioned.
Cereal grains are only one of many possible feedstocks to produce biofuel, so I suppose it would be important to look at the advantages and disadvantages of each. This is something I hope my professor will discuss in his presentation (I can give him some guidelines, but I wanted to gauge some discussion on the board first, which has not really happened unfortunately).
Biofuel from Cereal Grains:
Advantages:
1. Byproduct is still usable as livestock feed
2. Technology is available and affordable for production at a reasonable energy in/energy out (vast improvements have been made in recent years, so the argument that says it uses more energy that you get out is no longer valid AND only further improvements should be made)
3. A higher value product (fuel) is made from a low value product (starch)
4. There is a vast overproduction of these grains in North America, so this puts a good use to the excess grain - exports are somewhat limited by the storage capacity of the grain
Disadvantages:
1. It will always be more expensive then fuel made from sugarcane, putting it at an economical disadvantage for export; however, Brazil uses the vast majority of its own production
2. Potential increases in the food value - I say potential because many other factors such as drought played a major role in the spike of food prices around 2007. Since then prices have returned to near historical levels.
3. Ethanol made from cereal grains is not desirable due to the harshness on engine parts, such as gaskets; however, butanol a longer chain alcohol with more energy and more desirable characteristics is being researched as a future possibility
Biofuel from Algae
Advantages:
1. Only microbe that uses inorganic carbon (CO2) as a feedstock to make fuel - this has a plethora advantages
2. Can be grown on arid land or even buildings
3. Lipids have long carbon chains, meaning more high energy bonds and therefore a better fuel
Disadvantages:
1. Not entirely sure where the challenges lie (extraction? refining? growth rate?) Maybe someone else knows.