Reducing Waste

Trace minerals are usually added to a modern poultry diet in such small
amounts that many people forget how important they are to the
maintenance, health, and performance of a commercial flock. Although
acute or visible mineral deficiencies might seem to be a thing of the
past, if the diet lacks a particular essential mineral or a set of
them, the potential for very characteristic mineral deficiencies and
problems for the poultry operation exists.

Trace minerals are usually added to a modern poultry diet in such small amounts that many people forget how important they are to the maintenance, health, and performance of a commercial flock. Although acute or visible mineral deficiencies might seem to be a thing of the past, if the diet lacks a particular essential mineral or a set of them, the potential for very characteristic mineral deficiencies and problems for the poultry operation exists. 

Less is More. Excess trace minerals won’t improve bird performance but are excreted into manure, which can draw criticism for its potential to contaminate the environment. Advertisement

Real trace mineral deficiencies tend to be marginal and subtly show themselves as poor immune response, depressed growth, inefficient feed efficiency, depressed egg production and infertility. At the other end of the spectrum, an excessive trace mineral addition generally has little impact on bird performance, but draws much criticism on high poultry manure contamination to the environment.  As a result, there is a growing interest in the true trace mineral requirements of poultry and what is the best means of trace mineral supplementation.

A History Lesson
In retrospect, the National Research Council (NRC)  reviews and makes trace mineral recommendations for different poultry classes based upon periodic scientific research. Unfortunately, this research has become somewhat dated, because avian trace mineral research is not often the “hot-topic” of poultry nutrition discussion and questionnaire. In fact, over the last 20 years, less than two per cent of all research efforts have been expended on this subject. Therefore, current NRC trace mineral requirements poultry (NRC, 1994) contains a significant amount of carry-over recommendations in recent years.

Consequently, many commercial poultry diets have significantly higher trace mineral concentrations compared to those set by the National Research Council (NRC). Many nutritionists believe these existing published levels are inadequate to support modern levels of avian performance achieved by egg-laying chickens, breeders, broilers, turkeys and other commercial birds.  They also perceive that the best approach to take care of any puzzling or questionable bioavailability of most commercial inorganic mineral sources or anything that restricts its uptake by animals is to formulate with an “insurance factor” that in the end may meet all the animals’ mineral nutrient requirements. Upon examination of many domestic poultry diets, it is common to find out that many of them carry 200–500 per cent excess in trace mineral concentrations.

Where do we go from here?
We might start to determine the trace mineral recommendations for different avian species by using a different approach.

In the past, purified research diets were fed to different classes of poultry in order to isolate the studied trace element and to correct for possibly poor trace mineral level, and of unknown bioavailability in conventional feedstuffs.  Any experimental trace mineral added to these test diets was most likely of high chemical purity.  In contrast, more practical commercial diets do not have this luxury. Instead, they must rely upon such major feed ingredients, which at times provide significant quantities of trace minerals, although it is unlikely that these trace minerals can be utilized by birds.

For example in an unpublished 17-day trial, Appleby and Leeson measured the performance of male broilers fed corn-soybean meal diet with or without supplemental manganese. As a result, the unsupplemented control diet contained 12 mg/kg Mn/kg diet, which appeared to be adequate for broilers of this age under trial conditions.  Rather than suggest that this reflects true commercial trace mineral requirements for this class of poultry, the researchers did not discount the antagonism of the other trace elements which seem to justify 70 mg Mn/kg added to the control diet.

Real trace mineral requirements of poultry
One of the greatest paradoxes of trace mineral nutrition in poultry and other livestock species is that an animal requires a specific amount of a particular element, and yet this basal requirement is significantly increased due to poor bioavailability of consumed trace mineral sources, natural barriers to gastrointestinal absorption, antagonism by other nutrients, and inefficiencies of metabolism. As a result, much added dietary trace mineral amounts are excreted and thus wasted.

However, organic trace minerals are now available that have superior and consistent bioavailablity and are not hampered by other antagonistic forces; the birds’ true trace mineral requirements can be not only achieved, but closely matched in a well-balanced diet. Consequently, less organic minerals are required to be fed, and without risk to animal health and performance. Ultimately, less organic minerals added to the diet, also means less undigested or unretained trace mineral excreted in the manure, and finally deposited into the environment.

Here is the evidence

• In 2002, Dr. Leeson from the University of Guelph investigated how much trace minerals are actually required by broiler chickens if respective organic minerals replace their inorganic counterparts. They found that caged- and floor-reared birds fed just 20 per cent of the industrial recommended levels of zinc, manganese, iron and copper in chelated form had similar body weight gains, and feed efficiency to those birds fed respective inorganic trace minerals. Further data revealed that fecal output by a barn housing 100,000 broilers associated with the study, had a drop by 40 per cent in zinc, 50 per cent in manganese, 15 per cent in iron and 10 per cent copper excretions.

• Ao and Pierce (Alltech – University of Kentucky Alliance) investigated the relative bioavailability value of Bioplex Zn compared to Zinc Sulphate for broiler chicks. Another objective of their study was to determine the zinc amounts required in each form to meet the zinc requirements of broiler chicks fed a standard corn-soy diet. This study showed that Bioplex Zn had a 177 per cent bioavailability factor on weight performance data and 202 per cent bioavailability on bone tibia data compared to inorganic zinc sulphate. The data also showed that it took about 50 per cent (6.3 mg/kg diet) of the required zinc in Bioplex Zn form versus zinc sulphate to meet the minimum zinc requirements in the experimental chicks.

Experiments illustrate the breakthrough potential for formulating  organic trace minerals into poultry rations. The advantages of total trace mineral replacement are as follows:

• The true trace mineral requirements of different classes of poultry are visibly matched by organic minerals.
• Trace mineral requirements of different classes of poultry are achieved with significantly lower levels of organic minerals.
• Much less risk of creating antagonistic relationships among essential trace minerals in the diet.
• Formulated trace minerals are efficiently absorbed, metabolized, retained and utilized and less is excreted into the manure.
• Organic trace mineral supplementation is not confined to the laboratory, but is applicable to commercial broiler breeders, broilers, layer and other types of poultry operations.