The government or other statutory authorities may mandate that all animals should be tagged whether pets,cattle,livestock or endangered wild species.
Pet tagging would have the records of pet health easily available including vaccinations for, say! The rabies vaccine which is normally given to pet dogs.Livestock tagging would enable government monitoring of the food chain.
International trade bodies and industry associations may mandate that all food produced from farm animals require traceability to the particular animal from which the food was made, So the records of the animal can then provide clues.This will be useful in case of future outbreaks of hitherto unknown diseases.
Endangered species tagging can enable environmental agencies to monitor the numbers of particular animal races. Radio tagging is present being used, but not on a large scale.Many places still use crude methods like looking for the animals droppings, spotting them from the air and etc.Due to this only estimates of numbers are available, never the actual numbers.Also there is now way to have a census or to know if poachers have killed any of the animals.
