A couple of years ago when still relief milking there some unexpected deaths in the herd within a couple of days. During my weekend shift another girl began staggering and went down in the yards and subsequently died. The next morning another girl was found in the night paddock in a bad state and unable to get up. The dairy farmer was contacted and he administered a calcium supplement intravenously and the cow recovered.
The problem was not milk fever. The symptoms apart from staggering gate was a foaming mouth. The problem was poor grazing management. All the cows who had died or became ill had calved in the previous week. Prior to that they been in an isolation paddock with little green feed and were only fed silage and calving pellets. The night paddock into which they went after calving was a lush green clover/Kikuyu/rye paddock in its peak thanks to a very good autumn.
The deceased and recovered unwell had experienced grass tetany as a result of a sudden change of diet from dry to nitrogen rich green feed. An oversight by the dairy farmer who had become complacent after many years of mediocre seasons.
This week while collecting milk the younger dairy farmer mentioned that a dozen or so of his herd had come in during the week all staggery and off their feed and milk production. After some inquiries and discussion the older dairy farmer chipped in "the youngin there was just a bit generous with a strip of Ryegrass earlier in the week".
So easy to do even by experienced farmers.
We sometimes forget how susceptible animals are when their feed routine is managed by us rather than nature. Cell grazing is a marvellous technique but requires vigilance.