ABSTRACT
Agriculture and animal farming have been major
human activities for thousands of years, as food is of
vital importance for the maintenance and quality of
life. These two activities have been closely interrelated
because animal farming makes possible to conversion
of low-energy, often indigestible, plant material into
high-value proteinaceous products such as meat, milk,
and eggs. Over the years, increasing interest has been
directed toward maximizing this conversion at minimal
cost, and new practices in animal husbandry have been
designed by controlling various factors such as genet-
ics, nutrition, health, management, and the environ-
ment. Modern farming systems involving intensive
rearing of animals in restricted areas are currently
being optimized throughout the world so that ade-
quate food supplies of animal origin for the increasing
world population can be produced at reasonable
prices. Major components in the structure of any modern
farming system are several antibacterial agents includ-
ing pharmacologically active compounds of both
natural and synthetic origin. Apart from treatments
such as injections, most of these agents are adminis-
tered to animals as feed additives or in their drinking
water to cure outbreaks of disease whenever they
occur. Their use has become essential in intensive
livestock farming because the rearing conditions of a
large number of animals in close confinement could
hardly be more favorable for the frequent incidence
and rapid spread of disease. Because it is sometimes
too late to effect a cure once the clinical signs of an
outbreak are recognized, antibacterials are also fre-
quently added to feeds at subtherapeutic levels for
preventive purposes or to assist in increasing the feed
conversion efficiency and to stimulate growth. These
beneficial uses may result, however, in the appearance
of residues of the administered antibacterials in the
edible animal products in cases where the period of
time between the cessation of antibacterial adminis-
tration and the animal’s slaughter or the collection of
milk and eggs is not long enough to allow the residues
to be depleted from the animal’s body. Such contami-
nated food can readily reach the consumers, and
increasing concern has been expressed as to the
possible hazards for public health. Since human food
safety is the foremost consideration in food animal
production, superseding even the obvious importance
of economic factors, international systems of legal
control have been established to prevent residue-
contaminated animal products from entering the
human food supply.
