Which would give a cow more energy, a kilo of human flesh or a kilo of plant material? Can we assume that a cow has the enzymes to digests human flesh?
Assuming that they could process it (but you seem to stipulate that), it is no contest. Meat blows away grass in terms of calories.
Don’t they give cows rendered cow flesh already?
I was looking for the factual answer. Can a cow digest the meat? I think they can.
I know they can digest cellulose but I believe it is very inefficient for them to do so. On the other hand, cellulose is glucose. Once it is digested, there is a big energy gain for them. As I remember, glucose is a larger energy molecule than protein.
You have to remember that a cow’s first stomach is an anaerobic digester. So the question isn’t only, can the cow eventually digest the meat, but also, will the meat disrupt the microbial consortium in the first stomach? There are three (at least) types of microbes working together: hydrolyzers (which break down the cellulose), acid formers (which form acetic acid from the breakdown products) and methanogens (which shift the acetic acid to methane). It’s a complex dance between all of them and the cow.
Don’t know what the answer is, but I’m pleased to be ignorant at a higher level. Oh, did you know that the ag folks who were first looking into suppressing the production of methane by cows were doing so as a way to increase feed efficiency? Any carbon atom from the feed that gets released as methane (by burps, not farts - another common misconception) is an atom that hasn’t gone into the building of cow meat. When global warming became a concern all those ag researchers said, “hey! look! new food source!” (Most of the researchers I’ve know have spent at least a third of their time writing grants to try to fund next year’s research.)
Also, what the cow digests in the subsequent stomachs is part half-digested grass, part acetic acid, and part microbe bodies. Microbes eat grass, microbes grow, cows swallow and digest microbes. So they can digest the protein in the microbes, at least.
Both sugars and proteins have 4 kcal per digested gram. To get a pound of digestible protein from meat a human being needs to eat a little over a pound of 100% lean meat. To get a pound of digestible sugars from unprocessed vegetation a human being will probably need to eat more than is actually possible. Now, this can be represented as X kcal/lb of meat and Y kcal/lb of unprocessed vegetation. It is clear that for humans X is significantly higher than Y. You are asking if for cows is X still higher than Y despite less adaptations to eat meat and more adaptations to eat plants, is my understanding correct? I don’t actually have an answer (although my guess would be yes, X is still higher, but there might be other reasons cows shouldn’t eat meat even if available, like gastric distress and most meat generally trying to fight back when eaten), but I’m hoping this can clarify it for other posters.
Ok. A cannibal cow would eat other cows, not humans.
Homotarian? Humanitarian?
[sings] It was a one eyed one horned flying purple homotarian! [sings]
Homivore. 
Well, I’ve watched cows eat their afterbirth. Can’t say why, or even if they’re aware of what they’re doing, perhaps the cow thinks the afterbirth is a fresh born calf and is trying to clean said calf. As far as I can remember it’s only when the afterbirth expels straight after giving birth some go for it, if it’s a couple of days before it’s expeled, the cow doesn’t seem interested.
So, some cows eat meat already, just not human
I thinks that’s been stopped because of BSE, but I’m willing to be corrected. My cattle were only fed pasture based feed: grass, silage, hay, turnips.
Movie trailer tonight 
Almost fits the OP :eek:
Horses & other equines do this also.
The generally accepted reason is that it protects the herd, because leaving a bloody afterbirth would attract predators with its smell.
I’m sure the feeding of animals on protein derived from their own species (or indeed their own family or order, possibly) is banned, but cattle are routinely fed animal protein in the form of processed fish meal.
I thought it was instinctual in all mammalian species because the hormones in the afterbirth stimulate lactation (humans? - some people eat their afterbirth).
Given that one of the speculative sources of BSE was scrapie (a sheep prion disease) from rendered sheep meal, most mammalian products are off the bovine menu.
Of course, has anyone asked the question - do fish get prion diseases?
I think cows should eat grass and corn, myself. And drink beer, too.
Why can’t I get NZ beef in the UK?
Si
No, lactation has started some time before. Dropping wax and dripping milk from the mare’s teats is a common sign of imminent birth. Obviously, in a successful traveling-herd species, the milk would have to be already produced and ready for the foal to suck right after birth.
After that, it is the sucking of the foal and emptying of the teats that keeps lactation happening. Until the foal is weaned, mares will keep producing milk. (Though the hormones of pregnancy will affect this – the mares body starts to concentrate on the new, unborn foal. Most mares will start to refuse to allow a foal to suck, if they haven’t been weaned by this time.)
After much digging, I ended up here
The EU has given NZ a quota of 1300 tonnes yearly (big freaking deal) of “High Quality Beef” :rolleyes:
A kg of grass, no competition. Contrary to what Shagnasty said grass contains far more calories than meat. Grass is mostly cellulose, which is just a long chain sugar. It represents more energy than an equivalent mass of table sugar. In contrast protein contains fewer claories and far, far fewer biologically available calories. That’s why even an omnivore like a person will starve to death if fed a diet of lean meat.
The enzymes aren’t the problem. Cows manufacture protease enzymes, they are also home to numerous microbes that produce proteases. The problems are that the meat is a pollutant, and that the meat has to run the gauntlet of protein starved microbes first.
To deal with the pollution issue, a cow is just a big microbial fermenation vat on legs. If you feed meat into a fermentation vat you can get some really nasty microbes growing. The biggest problem is Botulinum which will thrive if it gets into the a rumen loaded with fat. Cow dies within hours.
The next problem is that the microbes in a cows rumen are chronically short of protein. They have evolved to strip any protein they recieve as soon as they can. If you feed a cow meat, or even just a high protein feed source, the microbes glut themsleves on protein and then start producing some nasty wastes, including organic acids and urea. That causes liver and kidney damage as well as scouring, which is basically a flushing of the intestinal tract. Not pretty and not a good way to take in calories.
Cattle and other ruminants do eat meat naturally, even in the wild, but they do so primarily as a protein or mineral supplement. They don’t eat it in huge quantities as an energy source.
Anthropophage. (adv: “anthropophagous”)