Gambel oak is a shrub or small tree. It grows in dense thickets on foothills and mountain slopes, up to an elevation of 9000 feet. Oak usually starts growing in early spring before other range plants. How It Affects Livestock Oak toxins are incompletely identified, but are most likely a gallotannin or a combination of gallic acid and tannic acid. Buds, small leaves and flowers are most palatable and most often associated with livestock poisoning.
Poisoning can occur later in the fall and winter when acorns are available.
There are anecdotal reports of poisoning when cattle drink water that has soaked oak leaves. Poisoning results in severe enterogastritis and nephrosis. Death from oak poisoning may occur in a few days to 2 weeks after the cattle first show signs. How to Reduce Losses Livestock losses from oak poisoning can be reduced by conservative grazing and proper seasonal use of shinnery and Gambel oak ranges. In shinnery areas of the Southwest, livestock owners should reserve pastures with the least amount of oak for early spring grazing.