Implication
Ever venture far enough off the beaten path to a place where a cow's life is preeminent over yours?
We have all seen the "WATCH FOR CATTLE" signs. Since I don't think the highway department has a compelling interest in cows grazing on nearby fields, we will assume they are implying "on the road." If no cows are seen in a short distance, most drivers return to speeding since we are all aware there are no "STOP WATCHING FOR CATTLE" signs.
By placing more value on the cow (implied) than on the motorist, it sends a clear message - speed, and you are responsible for your own loss of life. Could the highway department have said "SPEED AND EAT RIB EYE." Unlikely, since it implies your survival.
The meaning and implication of words are determined by the reader, not the writer. What does the above sign imply to you. Happy New Year. Have a great 2014.