Neil:
Pardon me for quibbling, but I do not believe meat-eating necessarily reduces the human food supply. Some food animals do us the tremendous favor of converting grass (bound into indigestible cellulose) , which is utterly useless for human food, into high-quality food. Maybe sometime people are going to make fuel out of switchgrass (I’m a bit skeptical myself because switchgrass is touchier than a lot of people think, and I wonder if cellulosic methanol is economical) but switchgrass can be made into food NOW, by feeding it to ungulates like cattle and sheep.
Certainly transportation is an issue with hay. So it is with grain. It is no accident that feedlots and production facilities are located near the grain supply and also the grass supply. It’s cheaper, relative to value, to ship cattle than grain; certainly more cheaper than transporting hay. It’s cheaper still to transport meat that has been processed. High value cargo.
In my opinion (and increasingly in the opinion of feedlots as well) far more grain is fed to ungulates (cattle and sheep) that is necessary or even desirable. What ungulates do best is convert grass to meat. People do like that “finished” marbling, but you don’t have to feed grain for months and months to do it.
Everytime something changes, it takes awhile for adaptations to be made. With cattle, certain breeds enjoy popularity, then lose it, then sometimes gain it again. While grain was extremely cheap, large continental cattle were popular. Lots of pounds per set of hooves, and continentals grow very fast on grain. The classic British breeds (Hereford, real Angus, Shorthorn) are more efficient than Continentals in producing meat from grass, even very low quality grass, and take less grain to fatten, if that manner of fattening is desired. (people do like grain marbling, but it’s not the only way to do it) I have never raised longhorns, but I know people who do, and while there are objectionable things about them, one has to admit that they are very good at producing meat from the worst quality forage that can be imagined.
The U.S. (and some other countries as well) have immense stretches of grassland. Some could be converted to grain crops, but many cannot. The ONLY thing some areas can grow well is grass, and the ONLY things that can turn it into high-protein, high vollume, tasty food at low cost and with minimal energy use, are ungulates.
In some places, feeding hay in significant quantities cannot be avoided. In some places, very little is necessary, particularly if one uses the right methods. In some areas, like my own, one only needs to feed hay when the snow is more than one foot deep, refrozen, or if the grass is heavily glazed with ice; all quite rare. But even here, adaptations have to be made to do that. I agree with Vern that the cost of hay has gone up because of transportation costs. to that I would add the fuel cost of producing the hay to begin with. But I also maintain that a moderate amount of surplus is produced, and a lot more is fed than is really necessary.
Such things are a matter of making the right adaptations in light of changed circumstances. And people do make such adaptations. Oftentimes, solutions do not require radical measures. Sometimes solutions are not adopted because other ways are easier at some point in time. When grain and transportation were cheaper, people did not concern themselves too much with alternatives.