That’s a good point. I think some cattle in the U.S. (like in Wisconsin) are almost totally corn-fed, while in Texas and Florida they are partly grass-fed ((corn-fed tastes better)).
But it’s not just the crops they eat that contributes GHGs, but also their digestive system and CH4, so that might make them more GHG/unit of protein or calorie intensive than vegetarian diets (but I’m not sure). That is the problem with rice – the CH4 releases from paddy fields.
Undoubtedly some cattle are almost entirely grain fed in places that are not really suited to cattle raising but in which farmers feed their “waste” corn. In more temperate places like where I live (Southern Mo) cattle are entirely grass-fed all the way to “feed lot” weight, which is pretty close to slaughter weight. They are fed “grain” for 80 to 120 days for the “marbling”. Since the recent trend is to feed less, feed lots now pay higher per pound for animals that are closer to slaughter weight than they used to. Breed makes a big difference in that, but far and away most of the weight is put on with grass.
Other than perhaps northern farmers who feed their own otherwise unmarketable grain to cattle, (and even that is usually a corn silage that contains the stalks and leaves as well)competent cattlemen do not feed significant amounts of grain to cattle. You will lose your backside doing that. Cattle do not need grain in order to thrive and grow, and it’s a terrible waste of money to give it to them all the way to feedlot weight.
I put “grain” in parentheses because they really aren’t fed much real grain in the feed lots. Most of it is a formula in which the main protein ingredient is actually distillers’ grain; grain from which the alcohol has been distilled and extracted, and which is good for almost nothing else. It’s mixed with things like rice hulls, soybean hulls and the like. The corn that’s used is usually of a variety or quality that is not marketable for human consumption.
I am aware that cattle contribute some methane to the atmosphere through belching and such. But we might remember that before white settlers arrived in this country, the country contained approximately as many buffalo as it now contains cattle. Their digestive systems are the same. That does not count the enormous number of elk, antelopes and deer that were there before, and whose digestive systems are virtually the same. So, cattle add no net methane to what was produced here in 1491, and probably less.
What would happen if we destroyed all the cattle? Well, nature abhors a vacuum and, unless it was prevented, the grasslands would fairly quickly refill with other animals having the very same digestive systems, and there would be no net methane reduction unless the government forever sent out teams to eliminate grass-eaters from the grasslands.
And, of course, 1/3 of the world’s useable land would become totally useless to human beings. Humans would leave them, of necessity, and the killing teams would have to be fairly substantial in number. We can’t digest grass, period.
Grass, of course, is a net “eater” of carbon, particularly if something eats it and converts the carbon to something like meat instead of just leaving it to decay. But few natural things capture carbon better than “adolescent trees”. Some grasslands (but certainly not the biggest part) can be converted to “silvopasture”, in which pasture is interspersed with trees (usually, but not necessarily in rows). The advantages are better grass growth, less drought damage, heat respite for cattle and (if one likes the thought) carbon sequestration.
There is some crop land where I live, though it is mostly grassland and forest. The energy (name removed by moderator)uts into crops are incredibly high. Energy (name removed by moderator)uts into grass are very low, almost nonexistent, depending on how you do it.
Yes, energy is consumed and CO2 generated when hay is harvested and stored. But that’s still not remotely comparable to what it takes to simply prepare the ground for a crop, let alone sow, spray, spray again, havest, haul, etc. And, in some places, (like here) the climate is such that, if you do it right, you might feed hay for only a couple of weeks/year.
Not saying all ranching practices are good. But perhaps the emphasis from an environmental standpoint ought to be on encouraging the best practices. Meat from grass contributes a very large segment of the world’s high-quality food supply, and when it comes to cattle, it’s pretty environmentally friendly.
