Trace minerals are the minerals that are required in
small quantities in animal nutrition. Some minerals are not required but may be
associated with the minerals required for animals. The essential and non-
essential trace minerals may be toxic
especially if present in large quantity.
The complexity of trace mineral in
animal nutrition requires a thorough review of functions, interactions and
availability of sources from time to time by the producer/ nutritionist. The trace
minerals of primary concern also in poultry nutrition diets and recommended by
the NRC (1994) include Zinc (Zn), Manganese (Mn), Copper (Cu), Iron (Fe).
Selenium (Se) and lodine (I).
Mineral , though being a small part of
complete poultry nutrition is critical for well being and performance of bird.
In the past 25 years, trace minerals
role in immune function and related physiological roles have gained importance.
New organic sources of trace minerals have been patented and marketed providing
a more available form of poultry nutrition trace minerals for the chicken.
Even though the daily requirement
of poultry nutrition trace elements is expressed in milligrams and micrograms,
they play a vital role in various body functions like synthesis of
Metallo-enzymes, Enzyme co-factors, Hormone production etc.
In Poultry nutrition industry trace
minerals have a wide range of functions. It is important to understand these
functions in order to better understand how these minerals affect animal growth
and performance.
As described by Underwood and
Suttle (1999), the functions of trace minerals in poultry nutrition can be
broadly classified into four categories structural, physiological, catalytic
and regulatory functions.
1. Structural Functions -
Trace minerals in poultry nutrition can form structural components of organs
and tissues, such as Zinc, which is a structural part of membranes and
molecules.
2. Physiological Functions -
Minerals are involved in maintaining osmotic balance, acid base balance,
membrane permeability and tissue irritability in poultry nutrition.
3. Catalytic Functions -
Of all the functions, these are the largest. Trace minerals act as catalysts in enzyme
& hormone systems and also serve as integral structural components of
numerous metallo-enzymes.
These metallo-enzymes are
required for a broad variety of metabolic activities such as energy production,
protein digestion, cell replication, antioxidant activity and wound healing.
4. Regulatory Functions – In
animal nutrition these are illustrated by the role of trace minerals in
regulating cell replication and differentiation. While Zinc influences
transcription, lodine as a constituent of thyroxine is associated with thyroid
function and energy metabolism.
Micronutrients in as trace
minerals play a vital role in various metabolic, enzymatic and biochemical
reactions ultimately leading to better growth rate, egg production and in
overall poultry nutrition efficiency. Trace minerals have a very important role
to play in the mechanism of nutrient circulation within the animal body.
Deficiency or imbalance of any of these vital micronutrients for poultry
nutrition results in deficiency symptoms, metabolic disorders, poor growth
rate, low egg production, low hatchability and low poultry nutrition efficiency.
For Poultry nutrition trace
Minerals are absorbed in the intestine in ionic form. They are usually as
inorganic salts, which get dissociated after entering the system. The free metal
ion first gets attached to an organic molecule or "escort". Due to
multiple antagonistic reactions of ingredients in the animal digestive system
and limited ligand/ escort availability whatever minerals are able to find an
escort are absorbed and the balance is excreted.
Minerals find their use in
various industries and also vary in the forms in which they are available.
Hence, from a poultry nutrition standpoint, proper selection of the mineral
salts is important. In poultry nutrition the following criteria play an
important role in trace mineral salt selection
• Bio-availability
• Potency
• Availability
• Stability
• Purity
• Economics
In animal nutrition of these, bio-availability
is an essential criterion, as highly bio-available forms are able to meet the
birds' need, without much wastage. Purity of trace minerals is also important
as these trace mineral salts are by-products of the chemical industry and
normally do not undergo rigorous quality testing for purity. One of the most
important factors to ascertain prior to formulation is the state of hydration
of a mineral. Many minerals forms contain bound water which obviously dilutes
effective mineral concentration.
Example: lodine is the most
reactive element. Potassium lodide, stabilized Potassium lodide, Potassium
lodate, Calcium lodate and EDDI are the sources widely used for supplementing iodine
in poultry nutrition.
In poultry nutrition trace
elements in amounts exceeding animal requirements is widespread, probably
because it is inexpensive, unlikely to harm animal and may be beneficial. It is
desirable to identify maximum bio-available elements necessary to support peak
performances.
Trace minerals are available in a
variety of forms and periodically problems arise due to lack of knowledge of
the composition and/or stability of salts.
Poultry nutrition supplementation
of minerals to animals above requirements/needs is also a common practice as a
safety margin to prevent any likelihood of deficiencies. If any mineral in poultry
nutrition is supplemented or present in ingredients at levels higher than the need
of animal it may negatively affect the availability and absorption of other
minerals.
The general guidelines for
analytical parameters for selected mineral salts are as follows:
• Color
• Density
• Odor
• Texture
• Particle size, distribution.
Flow ability
• Hygroscopicity
• Uniformity
• Foreign matter and molds
• Lumpiness
• Compressibility
While analyzing the trace
minerals, international standard analytical methods like AOAC (Association of
Analytical Chemists) AOCS (Association of Oil Chemical Society), BP (British
Pharmacopoeia) and USP (United States Pharmacopoeia) are utilized. Some of the
parameters being analyzed and studied are: .
• Bio-availability
• Stability
• Inherent characteristics of the
salt
• pH
• Purity
• Electrostatic charge
• Potency
• Heavy Metal Content
The animal nutrition product manufacturers
are often concerned about space in the diet whilst designing during
formulations. There is trend towards making very concentrated mineral and vitamin
premixes to try and optimize on the space availability. In considering
concentration of mineral source, oxide appears attractive, since they
invariably contain the highest mineral concentration. Oxides however are potent
oxidizing agents and if stored with premixed vitamins for any length of time,
can cause destruction/ deterioration of vitamins that are susceptible to
oxidation.
In the Indian scenario, it is
observed that the trace minerals do not get due respect whilst formulating diets
in the poultry nutrition industry. Many of the trace minerals manufacturers
tend to formulate trace minerals in general and do not consider the different
requirements of broilers and layers. The requirement of each type of poultry
nutrition is different as they represent distinct categories with entirely
different needs.
Inorganic sources of trace
minerals are efficiently absorbed and utilized up to a point. Beyond a certain level
inorganic supplementation of trace minerals does not evoke a positive response.
Hence beyond a certain level of supplementation, organic forms of the essential
trace minerals should be incorporated in a ration in order to maximize animal
performance. Organic minerals have shown specific target tissue response, so
they are bound to pronounce better result/ response. As organic minerals are
absorbed more effectively with an advantage of better results at lower usage
level. For overall benefit in poultry nutrition giving supplemental trace
mineral sources that are readily bio-available to the animal will, further,
allow for a lower inclusion rate in the diet and thus minimize mineral losses
in animal excreta.
here are six types of organic
trace minerals available in the market. They are as follows:
1) Metal amino
acid complex
2) Metal
specific amino acid complex
3) Metal amino
acid chelate
4) Metal
proteinate
5) Metal
polysaccharide complex
6) Metal
propionate
In order to achieve optimum and
desired performance in poultry nutrition supplementation of trace mineral in
right and sufficient quantities is crucial.
In animal nutrition to meet the
increasing need for trace minerals to cater the growing production needs for
poultry, the industry has steadily been increasing the quantities of inorganic
trace minerals in the diet. Whether these high levels will fulfill the required
optimum trace mineral status is a question mark. Various researchers have
described the negative impact of high level of inorganic minerals, due to their
interactions and competition for absorption sites. Apart from this, higher
level of minerals in the diet will have a serious impact on environment in
terms of variable excretion of trace minerals in the excreta.
The most common antagonism occurs
between Zinc and Copper, as both compete for the same binding site during
absorption. High levels of dietary Zinc will inhibit Copper absorption, hepatic
accumulation and deposition in the egg. Ratios greater than 4:1 of Zinc :Copper
can be considered antagonistic. High levels of Calcium, Copper and Iron can
interfere with Zinc. Excess dietary Phosphorus will interfere with Manganese
availability in poultry nutrition. High Manganese increases lodine excretion
and reduces Iron absorption. Excess Calcium andPhosphorus inhibit Manganese
absorption. Iron and Cobalt slightly reduce Manganese availability. In poultry
nutrition These interactions can be reduced by supplementing a portion of the
mineral requirement through chelated minerals, which are protected from
interactions and have better bio-availability.
Whereas organic minerals may be
absorbed more readily, the option of providing the entire requirement of trace
minerals in an organic form is an option that is very expensive. To counter the
pricing challenge, several producers of organic trace minerals recommend their
products at very low levels which, often, depress production specially in the
long run.
This matter is further aggravated
by the availability of sufficient forms of organic trace minerals with varying
bio-availability.
It is observed that inorganic
trace minerals in poultry nutrition exhibit an equally good or better
bio-availabilitythan organic minerals especially at lower levels of
supplementation; hence the majority of the required optimal levels can be
achieved by adding bio-available forms of inorganic minerals procured from a
reliable source. To achieve a still higher mineral status in the bird, which
may not be possible by inorganic minerals for reasons explained above the same
can be fulfilled by adding appropriate forms of organic/ complexed minerals.
Trace minerals play a vital role in poultry
nutrition. The requirements of different segments of poultry, selection of the
salt, and the quality of the trace mineral used are areas that warrant
attention. Further, the bio-availability of inorganic minerals to the bird is
limited due to natural factors; hence the role of organic trace minerals to
improve mineral availability in high producing birds may be examined to provide
a viable solution to trace mineral in
modern day poultry farming.