It is a common assumption that goats should not be fed a diet which contains urea as a nitrogen source. Most concentrates labeled for goats are now formulated with "natural" protein. Rapid change to diets containing urea is particularly dangerous. The details of the toxic process are beyond the scope of this web page.
Tremors, protruding eyes, frothy salivation, frequent urination, shortness of breath, tremors, struggling, possible violent behavior.
Ruminal infusion of acetic acid and ice water; rumen innoculants; fluids as required. Help from vet may be in order.
Read feed labels carefully. Avoid any containing urea or ammonia compounds. Ask about any ingredients that are not easily understood.
For some time, urea was a common ingredient in concentrates intended for cattle. Therefore, goat raisers automatically shied away from all cattle feeds, which are generally quite a bit cheaper than goat formulations. But there is now a trend to use "natural" proteins in cattle feeds as well and considerable savings can be found in judicial use of cattle mixes, either blended with goat feed or used as is for bucks, non-producing does, yearlings, etc.