I'm a farmer too, this is not good advice.I am a farmer who has flown drones in my fields. My horses ignored it completely, my sheep as most sheep will run from any thing different, they did but not in a panic and stopped running with the drone still in sight. I reckon hill farmers could well make a drone a very effective tool for farmers. I haven't got cattle but they are more laid back than sheep.
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Horses are nervous animal "much given to flight" and could easily be started running with unpredictable results.
Similarly cattle - they have a herd mentality and one or two playfully jumping about *looking at it* can soon turn into stampede-like galloping with most of them not having a clue what the 'danger' is.
Cattle breeds vary considerably and some Suckler types such as Limousins can be very wild indeed.