I can verify firsthand that cattle can be persuaded to cross a cattleguard. My neighborss herd broke through a fence and out into the road and I had to chase them back up his driveway, over a cattleguard.
As for animals learning fear of humans: You need two assumptions. First, assume that animals of any given species have differing degrees of fear of humans. Second, you must assume that this level of fear is somehow (by “education” or genes) passed on to young.
So, we’ve got two deer. One deer tells his fawns that humans have gotten a bad rap, and they’re not really all that bad. The other tells his fawns that humans are scarry, and you should stay away from them. Hunting season comes. The frightened deer stays well away from humans, and the non-frightened deer decides to go up to the nice friendly two-legs and socialize with them. Guess which deer doesn’t have any more fawns?
So the next season, there are proportionately more deer which fear humans, and proportionately less which don’t, even though no deer which was shot ever returned.
I have about 50 head of cattle and about 6 cattle guards across my farm land…I’m 58 and just got tired of opening and closing gates. My regret is I didn’t do it years ago. They’re a huge time saver.
Anyway, to help answer questions above, cows will typically not even step on a cattle guard. They just sniff it and leave it alone. Cows are often active late into the night grazing but still won’t cross a cattle guard in the dark.
Cattle guards are a horse deterrent (10’+ front to back) but not recommended as horses are unpredictable. I used to live in Ocala, FL (horse country) and I got mixed reviews from horse owners about cattle guards ..but because of their value most wont take that risk. I would especially avoid most steel cattle guards as livestock hoofs seem to get trapped in the void below the pipe. I’ve seen pictures of cow and heard of horses strewn across a cattle guard after getting it’s hoof caught in steel piping.
For that reason I highly recommend concrete cattle guards as the beams are solid from top to bottom.
You can learn more about cattle guards on wikipedia but I’ve found an intelligent resource about cattle guards here:
Reported as spam.
Welcome, James and thanks for the info. Hope you stick around. I’m in your age group and always like to encourage the more (ahem) mature visitors! Where do you farm?
ETA: Dewey, what makes that spam?
Sorry to offend, Dewey? 
I have 100 acres in Monticello, FL
I think the spam alert is just because your link is to a commercial site, and first posts from a new user that contain links to commercial sites tend to be spam around here.
Also, it is traditional to respond to new posters who bump near decade-old threads with references to zombies, so, in your opinion, how large a cattle guard would be required to successfully stymie the advance of the legions of the undead?
People zombies or cow zombies?
Of course it’s spam. He claims to have “found an intelligent resource about cattle guards” but then lists the same site as his homepage in his profile. In other words, this isn’t some site he’s found on the web and has no association with; it’s his own website.
James, welcome.
Dewey, the link is informative, just because it’s commercial doesn’t make it spam.
Cow zombies.
GRRRAAAAIINNNS!
That’s an interesting tradition… What size does a ‘zombie guard’ need to be? Wide enough you can drive across. Since zombies seem to easily die by fire (at least in the movies) I guess I would now suggest steel piping that is pumped with propane - then lit as needed :).
Uh, good catch. That does make it spam. I am more informed than I was before though, so there’s that.
Now, on the important topic of zombies, I really don’t think the cattle guard idea has any application here. Only a head shot kills a zombie, so getting a rotting appendage stuck in a cattle guard just means the zombie will continue on, leaving that dead appendage stuck in the guard.
Net result is no zombie stopped, plus now the guard is going to get clogged up with rotting zombie parts. Never a good thing.
I don’t think a cattle guard would work on zombies. Since they’re even stupider and clumsier than cattle, the zombies are just going to stumble in. This means that instead of deterring an arbitrarily large number of cattle, it will become jammed with zombies and then stop working.
Cows must be born with a sense about cattle guards. Just put one in. My cows have never been exposed to one before and won’t come near it. Very expensive.
I agree Cold Dish. Steel cattle guards are expensive, but I think you’ll find concrete a lot less.
Cattle guards work because they shoot first and ask questions later. Don’t know about zombie guards though.
This is correct - a covered bridge is the answer to the question “How do we make a long-lasting bridge out of wood?” Wooden structures have an extremely long life (examples in Japan are well over 1000 years old) if you can keep water and fire away from them.
Still are.
The roof protects the bridge.
Cattle and horses cross water. They even swim. Like the university, Oxford. Which swims.
Horses like to walk on solid ground, a bridge sounds hollow. Ever see a trail class? There will be a little bridge probably no more than 6 or 8 inches off the ground, no water in sight and horses still won’t want to walk across it.