According to reports, the Madison County Sheriff's Office -- which is about an hour and a half north of Houston -- detailed the mysterious tale Wednesday ... including what had been done to the carcasses, like the removal of their tongues and flesh from parts of their faces.

The strange thing about this -- besides the fact that the same thing had been done to all 6 of the dead cattle -- is that the Sheriff's Office there says no blood was spilled or left behind.

This story gets even weirder ... apparently, the dead cows each belonged to different herds from different pastures -- and they were all discovered a Texas State Highway (unclear which) that connects Madison County, Brazos County and Robertson County.

In other words, it doesn't sound like any of these cows were found together -- on the contrary, it seems they were scattered separately along this remote and rural highway.

Now the kicker ... the Sheriff's Office says 2 of the cows had even more damage done to them in a surgical-like manner -- namely, the removal of their genitalia and anuses, which MCSO describes as being carried out using a circular cut with the "same precision as the cuts noted around the jaw lines of each cow." Ranchers in the area also claimed predatory scavengers would NOT touch these bodies ... some of which were apparently out there for weeks. One last spooky factor ... the grass around them supposedly looked undisturbed.

The Madison County Sherriff's Office says the cause of deaths for these cattle remain undetermined. They also say similar reports have been filed around the country.