4.
Conclusion
The
taste
system
consists
of
a
group
of
nutrient
sensors
evolved
to
evaluate
the
nutritional
quality
and
content
of
foods.
Differences
between
vertebrate
species
are
often
related
to
the
adaptation
to
food
properties
and
availability.
Birds
have
lower
taste
bud
numbers
than
mammals
which
has
been
assumed
as
a
proof
of
lower
taste
acuity.
However,
the
number
of
taste buds relative to the potential bite size is probably higher in chickens than in most mammals. The broad consensus related
to the lack of taste sensitivity in birds needs to be reconsidered in the light of emerging data. Chickens may not perceive
sweet and only three bitter TR have been found, a much lower number than any known mammal. However the bitter taste
repertoire of other bird species, such as the white-throated sparrow, is as broad as in mammals. Moreover, even chickens
have
an
acuity
to
avoid
glucosinolates
and
quinine
chloride
that
is
comparable
if
not
superior
to
some
mammals.
Chickens
seem
to
have
a
higher
sensitivity
to
the
bitterness
of
saccharin
than
mammals.
Furthermore,
birds
show
high
sensitivity
to
dietary
calcium
and
other
tastes
modalities
such
as
amino
acids
and
fats.
In
addition
the
presence
of
taste
receptors
in
the
chicken
hypothalamus
suggests
that,
in
birds
as
in
mammals,
they
may
also
play
an
important
role
in
energy
homeostasis
and the hunger-satiety cycle. All these novel findings open the door to practical applications relevant to poultry nutrition
that may lead to improvement of efficiencies in Ca/P, a decrease in P excretion and to a better understanding on how to
optimize
the
use
of
dietary
amino
acids,
fats
and
alternative
feedstuffs.
Acknowledgement
Part of this review was presented at the Australian Poultry Science Symposium 2012.