Feed Management - November/December 2017 - 22
22 ❙ FeedManagement
needs by modern strains are met
by simple increases in feed intake
in response to selection for growth.
However, the same may not necessarily be true of strains selected
for egg production. Genetic increases in egg production have
largely been accomplished with
minimal changes in body weight
and/or feed intake.
Effects of phytase
The industry's knowledge of
nutrition has advanced to the point
where specific nutritional requirements are better understood and the
bird can be fed to meet those needs.
However, the more we know, the
more we need to know. Today's typical poultry diet will likely contain
phytase with its ability to release
phytin phosphorus and reduce the
negative impact on mucus secretion
and chelation of cations (positively
charged), e.g. calcium (Ca), magnesium (Mg), zinc (Zn) which can
impact cation:anion (negatively
charged) balance and subsequent
The effect of phytase on mineral utilization is beginning to be
understood. Recent work done at
the University of Illinois indicated
that phytase addition to a grow/
finish pig diet increased standard
total tract digestibility of calcium
2 to 7 percent. This suggests that
the digestibility of various cations
may be increased when phytase is
included in a diet and that increase
should be taken into consideration
Relative response to added dietary Mg
of 42-day broiler diets
Source: Nelson, 2015
Body weight (BWT)
Feed conversion ratio (FCR)
Tibia bone ash (TBA)
Breaking strength (TBBS)
Relative response to MgO, %
STRENGTH WITH MAGNESIUM OXIDE
Mg, %, or, lb. MgO/ton, added to diet
The addition of reactive MgO to the diets of 42-day-old broilers
significantly (P < 0.05) improved 42-day body weight and feed
conversion ratio by ~3 and ~2 percent, respectively. The impact MgO
addition on bone strength-related variables was relatively greater,
resulting in ~7.5 and ~4 percent, increases in tibia bone ash and tibia
bone breaking strength, respectively.
in practical formulation.
Does raising either calcium or
phosphorus levels increase the magnesium requirement of the chick?
Does this mean poultry may respond
to supplemental Mg in today's phytase-containing diets?
Magnesium: a closer look
Magnesium is an important element in the skeletal matrix and plays
a significant role in nerve stimulation and muscle contraction. It is a
catalyst in about 400 different enzymes/systems involved in protein,
lipid and carbohydrate metabolism.
Magnesium is required for insulin
secretion and is a cofactor in the
production of glutathione peroxidase, an important antioxidant in the
body's immune system.
Magnesium oxide (MgO) is the
highest Mg-concentration mineral
that is readily available as an
animal feed ingredient. Not all
sources of MgO are equal to the
task of providing the necessary
Mg+ ion efficiently to a living organism. Solubility, reactivity and
bio-availability are all characteristics that differ from one MgO
product to another.
www.WATTAgNet.com ❙ November/December 2017