by Dr. Ioannis Mavromichalis
Ingredients with a high concentration in natural pigments are few among those commonly used in poultry nutrition, and such ingredients are sought after to produce all-natural eggs for specific markets.
Feeds
for commercial layers are usually supplemented with synthetic pigments
to ensure egg yolk has a desired and, even more importantly, consistent
color; ranging from golden yellow to deep orange-red depending on local
preferences. There is, however, a small but increasingly significant
market in which all-natural ingredients are all that are allowed to be
used in layer feeds, and as such, synthetic pigments are excluded. For
this market, for which egg yolk color is as important as any other
market, two aspects that largely control egg pigmentation must be
considered: type and concentration of pigments.
Pigments that impart a
yellow or orange color to egg yolk belong to an oxycarotenoid group
called xanthophylls. The most important xanthophylls for egg yolk
coloration are zeaxanthin and lutein. The former is causing egg yolks to
be more orange-red in color, while lutein imparts a more yellow hue.
The balance between these two major xanthophylls is what determines
final color in egg yolks. Equally important to this balance is the total
xanthophyll concentration in feed. As a rule of thumb, to achieve a
satisfactory saturation of color, the feed must contain at least 15-20
ppm total xanthophylls.
From among commonly
available ingredients, maize is considered a good source of xanthophylls
(20 ppm), followed by the less frequently encountered but very powerful
maize gluten meal (275 ppm), and the infrequently used alfalfa meal
(175 ppm). Maize and maize gluten meal are rich in zeaxanthin (4 ppm in
whole maize), whereas alfalfa meal is rich in lutein (64 ppm). An
unusual source of natural xanthophylls is marigold petal meal, which was
added quite frequently in commercial feeds before the advent of
synthetic pigments. The concentration of xanthophylls in Marigold petal
meal is 7000 ppm. More recently, the use of certain algae as a source of
natural pigments has been investigated as it was found they can contain
up to 2000 ppm xanthophylls.
Another consideration
in the effort to provide layers with feeds rich in natural pigments is
that xanthophylls are quite unstable compounds and as such they
deteriorate quite easily during storage. As such, the addition of a
strong (natural) antioxidant will help maintain the potency of natural
pigments for longer. In addition, avoiding excesses of vitamin A will
help increase yolk color intensity as this vitamin has been shown to
antagonize xanthophylls in their role as pigments. Finally, ensuring
pullets enter egg production with highly colored shanks (by providing
high levels ofxanthophylls in the grower feed) will maintain a deeper
egg yolk color for longer as hens draw from their body pigment reserves
(shanks and skin) to supplement what they receive from their feed on a
daily basis.
In conclusion, layer
feeds based on maize and supplemented with alfalfa meal or maize gluten
meal can satisfy the need for all-natural eggs with sufficient yolk
coloration. Deeper color can be achieved by using marigold petals and
algae, but the xanthophyll composition of these ingredients can be very
variable as it is product specific.
Sumber : Poultry International
Sumber : Poultry International
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