Chelated Trace Minerals Benefit Layer Performance30 November 2013
High performing layers face challenges that affect gut health and egg shell quality. Mintrex chelated trace minerals zinc, copper and manganese help develop key tissues which benefit the overall health and productivity of laying hens, according to Dr David Parker, technical consultant for Novus International, Inc.
The impact of genetic selection on the performance of layer hens has been dramatic. Hens reared in colonies now produce up to 350 eggs over an 80-week period.
Free-range hens face additional challenges that affect gut health and shell quality. This requires nutritionists to provide a balance of key nutrients to sustain the health and welfare of the bird and to ensure the quality of the product. As with other production systems, the requirements for the major nutrient groups are well established, and more recently, the focus has shifted to evaluate the importance of key micronutrients in maintaining metabolic balance. For example, zinc (Zn), copper (Cu) and manganese (Mn) are known to have specific roles in avian metabolism, all of which are relevant to the laying hen (Table 1).
Trace mineral supply within the diet has traditionally been achieved through the use of inorganic trace minerals (ITMs). These are the sulphate or oxide salts of the mineral and, commercially, are often included in the diet at levels in excess of those recommended by national bodies such as the National Research Council (NRC). This reflects the uncertainty of the uptake of mineral elements from ITM sources and the desire to ensure an adequate supply to the tissues of the bird.
Concern over the bioavailability of key trace minerals has resulted in the development of sources bonded to organic ligands, the organic trace minerals (OTMs). This process reduces interactions within the gut and delivers the mineral to the site of absorption in the intestine, improving uptake to the tissues. One such OTM is the chelate formed between the mineral element and two molecules of methionine hydroxy analogue (hydroxy methylthiobutanoic acid, HMTBa). These chelates were recently registered as a mineral source by the EU Authorities under the latest regulations, Reg (EC) No. 1831/2003 (Mintrex Zn, Mintrex Cu, Mintrex Mn, Novus International, Inc.).
The chelate structure has been shown to confer stability at low pH, providing a mechanism for the passage of the mineral through the acidic foregut to arrive intact at the absorption site.
Further studies investigating the response within the intestinal cell have shown a significant increase in the activation of a key genere participating in mineral uptake, metallothionein, by Mintrex Zn when compared to ITMs and other OTM sources.
Impact on Health and Performance
Zn, Cu and Mn are all essential for the synthesis and deposition of connective tissue and bone.
Studies in broilers have shown improvements in intestinal breaking strength, foot pad quality and bone strength when Mintrex is included in the diet. More recent work with layers provides further evidence of these effects. One such study was conducted over a laying cycle with four treatments: control, Zn, Cu and Mn ITMs at 100 per cent or 50 per cent commercial levels, and Mintrex at 50 per cent commercial inclusion. In addition to production parameters, tibia bone strength was measured at 80 weeks. The results are shown in Figure 1.
As a consequence of its role in the activation of key enzymes, Zn status has a direct effect on immune function in the bird and the source of the mineral influences this process. A study in which layers were challenged with sheep red blood cells reported an enhanced immune response at week 63 in hens fed diets containing the HMTBa chelates compared to ITM sources.
Further evidence of the role of trace mineral supply and the health of the bird is shown in studies investigating the oxidative stress status of broilers. Oxidative damage to the tissues is regulated by a number of systems, including the activity of the enzyme superoxide dismutase which is sensitive to tissue trace mineral supply. In an experiment in which broiler diets were supplemented with Zn, Cu and Mn as either the ITM, Mintrex or a competitor OTM, the plasma concentration of lipid hydroperoxide, a breakdown product of tissue lipid damage, was measured. Peroxide concentration was significantly lower in the birds supplied with Mintrex, confirming that overall health status in birds is significantly enhanced when the trace mineral source is Mintrex.
Key processes associated with eggshell deposition and egg formation also would be expected to be sensitive to trace mineral supply and recent trials support this thesis that calcification of collagen depends on enzymes with trace mineral cofactors Zn, carbonic anhydrase; Cu, lysyl oxidase; Mn, glycosyl transferase. Formation and calcification of the collagen matrix is dependent on enzymes which require trace minerals as essential cofactors. For example, Mn-deficient layers have a lower shell mass and shell defects due to low activity of glycosyl transferase which is essential for proteoglycan synthesis.
Similarly, the enzyme carbonic anhydrase is essential for calcium deposition to form shell structure and is Zn-dependent. Egg production decreases in birds that are Zn-deficient.
Application in Layer Diets
The use of OTMs in layer diets is designed to improve the supply of key trace minerals to the tissues of the bird in order to support both productivity and health. In addition, due to the improved absorption efficiency, there is the added benefit of reducing overall mineral content of the diet and the subsequent environmental impact of the layer operation.
Studies to investigate these effects have been carried out in both field trials and experiments with replication of dietary treatments to allow statistical analysis of the data. In an early field study with layer breeders, eggshell strength was investigated over a 45-week period with two diets, one containing ITMs at (ppm) Zn100:Cu10:Mn100 and a test diet with Mintrex at (ppm) Zn50:Cu10:Mn65.
The effect of the OTM treatment on eggshell strength over the period of lay from 35 to 80 weeks is shown in Figure 2. Eggshell strength, measured in newtons, was consistently higher (P<0.001) with 3.6 per cent stronger eggs in the OTM group over the experimental period, resulting in more saleable eggs.
In a second experiment, layer performance over 44 weeks on a control diet with no added trace minerals was compared to birds fed diets containing Zn, Cu and Mn ITMs at two levels or Mintrex.
A total of 144 W-36 laying hens were allocated to four treatments with 36 hens per treatment and one hen per cage. The two ITM treatments had inclusion rates at 100 per cent and 50 per cent of industry levels, while Mintrex was included at 50 per cent of the industry standard rate. Laying performance showed a significant improvement over ITM's with Mintrex included in the diet at 50 per cent of the recognised commercial level (Figure 3).
Use of Mintrex Zn, Cu and Mn resulted in improved performance by the birds when compared to both equivalent level of ITM (40Zn:10Cu:40Mn) and the commercial level (80Zn:20Cu:80Mn) demonstrating the value of using a highly bioavailable source of these key trace minerals in layer diets.
Further analysis of eggshell structure showed a consistent increase in eggshell thickness in the birds fed the chelated minerals which was statistically significant (P=0.02) at week 74 of the study. Similarly, eggshell strength measured over the study period showed a significant improvement in birds fed diets containing Mintrex at week 68 (P=0.05).
This effect on eggshell quality was confirmed in a field study in Brazil where over a nine week period (weeks 72 to 81 of lay), substitution of 50 per cent of the ITM in the diet with Mintrex resulted in a 3.2 per cent reduction in cracked eggs and a 2 per cent reduction in broken eggs. These results are summarised in Figure 4.
In order to identify the potential benefit of individual forms of Mintrex versus ITM's on layer performance, a recent study has compared the effect of each organic trace mineral source included in a diet based on inorganic salts. The control diet was supplemented with Zn, Cu and Mn at 30:10:30ppm as sulphates and in the experimental diets, Zn or Mn were substituted at 20ppm with the appropriate Mintrex and the Cu source was included at 10ppm.
The experiment lasted for 14 weeks (weeks 39 to 52), and at 48 weeks, eggshell thickness and hepatic enzyme activities were measured. Eggshell thickness was significantly increased by the inclusion of either Mintrex Zn or Mn in the diet when compared to the ITM group (P<0.05). In addition, inclusion of Mintrex Zn increased the hepatic activity of the enzyme carbonic anhydrase (P<0.05), and the presence of Mintrex Zn stimulated Mn-superoxide dismutase (P<0.05) when compared to the inorganic sources.
This data confirms that the increased bioavailability of the trace minerals from the Mintrex results in specific effects in the tissues of the bird improving both health and performance over ITM's.
The key role of trace minerals (Zn, Cu and Mn) in metabolic processes is apparent when diets deficient in these micronutrients are fed to high performance poultry, such as layers.
Recently, studies have been carried out using a defined chelate based on the interaction between a trace mineral and two molecules of methionine hydroxy analog. Comparison with both ITM and other OTM sources indicates that Mintrex improves tissue supply of the trace minerals Zn, Cu and Mn and has a direct effect on connective tissue and bone development in addition to improving immune response in poultry. In layers, this has an impact on bird health, eggshell strength and egg quality factors which are critical to performance under current production conditions.
Mintrex, therefore, also can provide additional support when the period of lay is extended.
These highly-bioavailable mineral sources also allow nutritionists to reduce the inclusion rates of trace minerals while still meeting the requirements of the bird.
Use of Mintrex trace minerals in this way provides a direct benefit to the environment through reduced mineral content of the litter.
This article was originally published in 'World Poultry'.