Acorn Poisoning
Many cattle graze pastures and rangeland also contain oak trees; as a result on years with heavy mast crops like this year, there is the potential threat of cattle consuming acorns. Acorn poisoning is usually not an issue unless forage is short and cattle get a little hungry. However, this is not always the case, cattle are curious and if there are lots of acorns they are likely to try them. For whatever reason cattle like acorns and once they learn to eat them they are hooked and will seek them out.
The tannins in the acorns are what can cause gastrointestinal issues, kidney failure, and death in cattle. Often cattle that have been consuming acorns will have very dark, black, or bloody manure. Typically they will be dehydrated, have a loss of appetite, weakness, and will usually just appear poorly. It is not uncommon for cattle to die if allowed to continued access to acorns.
There is really no good treatment options for cattle that have been feeding on acorns to the point that they are exhibiting the more serious symptoms. If caught early, removal from the field or trap that has the acorns is the best option. Keeping adequate quality forage out for your cattle will often keep them from ever eating acorns in the first place. Later in the season, it appears acorns become less palatable and cattle are less likely to eat them.
Cattle are not the only livestock that have issues with acorns. Sheep have a similar liking for acorns and exhibit the same symptoms as cattle. Like cattle, sheep can die from acorn poisoning if not caught early. Goats, horses, and other livestock can also get acorn poisoning but it appears to be much less likely than in cattle and sheep.