Accidents do happen - luckily we are all very friendly on our yard and I would like to think we would not fall out about something like this. 'notes' of this kind of nature were banned some time ago as they cause much more trouble than speaking to each other. Not sure how you can replace a feed that has been mixed ready as I assume everyone feeds dif stuff. But a bag of carrots for the horses and choccies for the owners would have been the likely outcome for us. Feed is so expensive these days and the worst thing is that the owner laughed - her horse could have been dead if it had got to a bag of dry sugarbeet!
Personnally i would blame the YO\manager - there is no-way he/she should allow this sort of behaviour or "falling" out!
Also she should ensure horses cant\dont get out - and if they do sort out the aftermath! (if this happened on our yard - i would have been offering to replace stuff - as well as making sure the horse owner did!)
Like Nic said - we banned notes years ago - I always say -if you have a problem tell me and i will either sort it out or say it isn't worth bothering about (sometimes people do blow things all out of proportion) - obviously not you in this case.
We have a lovely yard where everyone gets on very well and would help one another out - etc etc! - BUT if in the past we have had anyone that has looked remotely like a bully (and there are quite a few in the horsey world) - then i have come down on them like a ton of bricks! - they dont tend to stop long after they have had a peice of my mind (but as yard manager i consider it my place to "sort" things out)
When i took on our yard 12 years ago, it had been empty for 12months as the owner had got fed up of the liverys falling out and had chucked them all off! - His main stipulation to me was - if i hear of anyone falling out - you all go! - so hence i run a tight ship (albeit very casually now adays as we have such a nice group of women)