Abstract:
Trace minerals when in contact with vitamin A in animal feed supplements and in animal feed have a deleterious effect upon vitamin A. This effect is reduced by treating trace minerals with lignin sulfonates before bringing the trace minerals into contact with vitamin A.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to trace mineral supplements which are suitable for addition to vitamin A-containing supplements. 
     2. Description of the Prior Art 
     It is common practice to add various minerals to poultry and livestock feeds. For example, many such feeds have mineral supplements added to them which are mixtures of materials such as limestone, steamed bone meal, dicalcium phosphate and salt. Such mineral materials are added to poultry and livestock feeds in amounts which are comparatively large as compared to the amounts of so-called trace minerals which are added to such feeds. The trace minerals most frequently added to feeds are compounds of manganese, copper, iron, cobalt, iodine, zinc and selenium. Supplementary amounts of these trace minerals are usually considered necessary for ruminants and all of them, with the exception of cobalt, are considered necessary additions for swine and poultry feeds. 
     It is also common practice to supplement poultry and livestock feeds with vitamin A. In many cases feed manufacturers purchase supplements for addition to their feeds which contain both vitamin A and minerals, including trace minerals. These supplements are quite often referred to as premixes, although they may contain other ingredients such as limestone and antibiotics. 
     Most minerals, particularly trace minerals, have a very detrimental effect on vitamin A. This is especially so in vitamin and mineral supplements because the concentration of minerals is considerably higher than in the finished feed product. The problem is intensified where the supplement or feed which contains both the vitamin and trace minerals is exposed to large amounts of moisture. Degradation of the vitamin also varies depending upon the nature of the carrier for the vitamin. Attempts have been made in the past to provide trace minerals in a form in which they will not detrimentally affect the stability of the vitamin. For example, according to Canadian Pat. No. 553,210--Hochberg--Feb. 11, 1958, trace mineral supplements have been prepared by admixing trace minerals with a normally solid wax-like material and a vegetable meal. 
     SUMMARY OF THE INVENTION 
     Trace mineral supplements containing one or more trace minerals can be prepared which when admixed with vitamin A have a less detrimental effect upon vitamin A. This is accomplished by adding lignin sulfonates to trace minerals before the latter are brought into contact with vitamin A. From about 2% to about 25% by weight of lignin sulfonates, calculated on a dry basis, based on the total weight of the trace minerals and lignin sulfonate is admixed with the trace minerals which are usually in the form of finely divided powders. Unless a solution of lignin sulfonates is used, moisture is added to the mixture of trace minerals and lignin sulfonates in an amount sufficient to solubilize the lignin sulfonates so that the latter can coat the trace minerals. Usually, no more moisture is added than is needed to form a slurry of the trace minerals and lignin sulfonates. Moisture can be added by spraying, by exposure to live steam or by adding water directly to the mixture. After proper wetting and blending, the mass is then dried by means such as a vacuum oven, spray drier, heated rolls, extruder or similar equipment suitable for the removal of the applied moisture. After drying, the product may be sized to a suitable fraction which is compatible with feeds or premixes. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Regarding selection of trace minerals any trace mineral which it is desired to incorporate in the finished animal or poultry feed may be used, the most common being manganese, copper, iron, cobalt, iodine, zinc and their mixtures. These trace minerals are usually in the form of their oxides, carbonates or their salts such as sulfates. Examples are copper oxide, copper sulfate, iron sulfate, cobalt carbonate, potassium iodide and copper iodide. These trace minerals are usually in the form of fine powders, i.e., finer than 100 mesh screen (U.S. Standard Series). 
     Lignin sulfonates are well-known materials. They are prepared from the waste liquors of sulfite pulping. Preferred are the water-soluble ammonium, sodium, calcium and magnesium lignin sulfonates. These products are available as aqueous concentrates or as spray or drum dried powders. When exposed to the digestive fluids of the animal, the lignin sulfonates separate from the trace minerals. Preferably, dry powdered lignin sulfonates are used with a minimum amount of moisture when mixing with the trace minerals. Preferably, 10% by weight of dry, solid lignin sulfonates is used, based upon the weight of trace minerals and lignin sulfonates. Final particle size of the treated trace minerals preferably is such that the majority of the particles pass through a 16 mesh screen (U.S. Standard Series) but essentially all will be retained on an 80 mesh screen (U.S. Standard Series), preferably on a 60 mesh screen (U.S. Standard Series) so that a multiplicity of small, solid granular particles is obtained. Note that hereinafter all screen sizes are understood to be based on the U.S. Standard Series of screens. 
     The vitamin A is usually in a matrix such as starch or in an oil carrier such as vegetable oil, e.g., cotton seed oil, corn oil, etc. Vitamin A is usually used as vitamin A acetate or vitamin A palmitate. 
    
    
     For a fuller understanding of this invention, reference may be made to the following examples. These examples are given merely to illustrate the invention and are not to be construed in a limiting sense. 
     EXAMPLE I 
     A trace mineral mix having the following composition was prepared: 
     
         ______________________________________          % by Weight   % by WeightTrace Minerals of Compound   of Element______________________________________Manganous oxide          84.75         55.0 MnCopper sulfate 6.60           1.65 CuCuprous iodide 1.70           1.11 I, 0.55 CuCobalt Carbonate          0.25           0.115 CoCalcium Carbonate          6-7            2-3 Ca______________________________________ 
    
     This trace mineral mix is used in feed for poultry, ruminants and swine. Dry powdered lignin sulfonates identified as Stapel and having the following composition was obtained from Consolidated Papers, Inc. (Appleton Wisconsin): 
     
         ______________________________________             % by Weight (Approx.)______________________________________Calcium lignin sulfonates               52Reducing sugarsHexoses             17Pentoses            8More complex sugars 19Moisture            5Inorganics          4______________________________________ 
    
     Portions of the above trace mineral mix and dry powdered lignin sulfonates were admixed in a weight ratio of 90% by weight trace minerals and 10% by weight lignin sulfonates. Then water was added to the mixture in an amount to wet the mixture sufficiently until it appeared damp or crumbly wet. Blending was carried out for a sufficient time to allow wetting of the mixture. Thereafter, the moisture was removed by placing the mixture in a vacuum oven. Finally, the mixture was sized to a particle size such that all particles passed through a 20 mesh screen and were retained on a 40 mesh screen. 
     Portions of the above trace mineral mixture, both treated with lignin sulfonates and untreated, were fortified to 1000 USP units of vitamin A per gram with vitamin A palmitate. The vitamin A palmitate was in a starch matrix and in the form of small platelets. The vitamin A particle size was such that all particles passed through a 20 mesh screen and essentially all were retained on a 60 mesh screen. Also, for comparison purposes, the same vitamin A palmitate in a starch matrix having a potency of 325,000 USP units per gram was included in the stability study. Approximately 0.3 gram portions of the vitamin A and approximately ten gram portions of the treated and untreated trace mineral mixtures fortified with vitamin A were assayed for vitamin A activity. The assays were performed using the United States Pharmacopeia Method, 19th Edition (1975) with slight modification because of the presence of the starch matrix, i.e., isopropanol was substituted for ethanol in the saponification step. The remaining materials were placed in capped glass containers and stored in a convection oven at 45°  C. At intervals of three, six, nine, and twelve weeks, samples were removed and assayed for vitamin A activity using the previously described sample quantities and assay method. The results appear in Table I. 
     
                       TABLE I______________________________________               Vitamin A Act-                           Vitamin A Act-               ivity of Mixture                           ivity of Mixture               of Vitamin A                           of Vitamin A and               and Untreated                           Trace MineralsTime                Trace Minerals                           Treated with Lig-(Wks.) Vitamin A    (Control) (USP                           nin Sulfonates@ 45° C.  (USP Units/gm)               Units/gm)   (USP Units/gm)______________________________________Initial  330,000 (100.0%)               1,030 (100.0%)                           1,083 (100.0%)3      309,000 (93.6%)               851 (82.6%) 1,310 (120.0%)6      279,000 (84.4%)               772 (75.0%) 1,150 (106.2%)9      274,000 (83.0%)               --          1,110 (102.5%)12     246,000 (74.5%)               685 (66.5%) 1,150 (106.2%)______________________________________ In the above table, the percentages represent percent vitamin A activity based on initial activity. All data reported in this table are within experimental error. 
    
     EXAMPLE II 
     This example illustrates use of lignin sulfonates in a more dilute trace mineral mix. Trace mineral mix and calcium lignin sulfonates having the same composition as disclosed in Example I were used in this example. In the same manner as carried out in Example I, a trace mineral mix treated with calcium lignin sulfonates was prepared having a weight ratio of 90% by weight trace minerals and 10% by weight calcium lignin sulfonates. 
     Portions of the above trace mineral mix both treated with lignin sulfonates and untreated were mixed with ground limestone (calcium carbonate). The untreated product was made by mixing 16% by weight trace mineral mix with 84% by weight ground limestone. The treated product was made by mixing 17.8% by weight coated trace mineral mix (16%÷0.90) with 82.2% by weight ground limestone. The particle size of the limestone was such that all particles passed through a 20 mesh screen and not more than 30% by weight passed through a 100 mesh screen. 
     Portions of the above limestone-trace mineral mix, both treated with lignin sulfonates and untreated were fortified to 1000 USP units of vitamin A per gram with vitamin A palmitate. The vitamin A palmitate was the same as used in Example I. Approximately ten gram portions of the treated and untreated trace mineral mixtures diluted with limestone and fortified with vitamin A were assayed for vitamin A activity as described in Example I. The remaining materials were placed in capped glass containers and stored in a convection oven at 45° C. At intervals of three, six and twelve weeks, samples were removed and assayed for vitamin A activity using the previously described sample quantities and assay method. The results appear in Table II. 
     
                       TABLE II______________________________________  Vitamin A Activity of                   Vitamin A Activity of  Mixture of Vitamin A and                   Mixture of Vitamin A and  Untreated Trace Minerals                   Trace Minerals TreatedTime   (Control) diluted with                   with Lignin Sulfonates di-(Wks.) Limestone        luted with Limestone@ 45° C.  (USP Units/gm)   (USP Units/gm)______________________________________Initial  870     886.5   100.0% 933   936.0 100.0%  903                    9393      780     742.0   83.7%  732   726.0 77.6%  704                    7206      679     679.0   76.6%  754   725.5 77.5%  --                     69712     681     562.5   63.4%  738   698.5 74.6%  507                    659______________________________________ In the above table, the percentages represent percent vitamin A activity based on initial activity. All data reported in this table are within experimental error. 
    
     EXAMPLE III 
     A trace mineral mix having the following composition was prepared. 
     
         ______________________________________            % by Weight                       % by WeightTrace Mineral    of Compound                       of Element______________________________________Zinc oxide (70% Zn)            28.32      19.8 ZnMaganous oxide (65% Mn)            12.30      8.0 MnFerrous sulfate (32% Fe)            46.88      15.0 FeCopper Sulfate (25% Cu)            12.00      3.0 CuCuprous iodide (32.6% Cu,            0.46       0.3 I, 0.15 Cu65.2% I)Sodium selenite (45.65% Se)            0.044      0.02 Se______________________________________ 
    
     In the same manner as described in Example I, portions of the above trace mineral mix were mixed with calcium lignin sulfonates having the same composition as disclosed in Example I in the following weight ratios. 
     
         ______________________________________Ingredients    % by Weight______________________________________Trace Mineral Mix          100     97.5    95    90   85Calcium lignin sulfonates          0       2.5     5     10   15______________________________________ 
    
     Each portion was then mixed with ground limestone so that each product contained a constant amount (50% by weight) of trace minerals. The amount of limestone in each product was adjusted to compensate for the various levels of lignin sulfonate added. For example the untreated product contained 50% by weight trace mineral mix plus 50% by weight limestone while the last product contained 58.8% by weight coated trace minerals (50% trace minerals÷0.85) and 41.2% by weight limestone. Each portion was then fortified to 1000 USP units of vitamin A per gram with vitamin A palmitate. The vitamin A palmitate was the same as used in Example I and the limestone was the same as used in Example II. Approximately ten gram portions of each of the five different compositions were assayed for vitamin A activity as described in Example I. The remaining quantities were placed in capped glass containers and stored in a convection oven at 45° C. At intervals of three, six and twelve weeks, samples were removed and assayed for vitamin A activity using the previously described sample quantities and assay method. The results appear in Table IV. All data are the average of duplicate determinations. 
     
                                           TABLE III__________________________________________________________________________               Vitamin A Activity of Mixtures of Vitamin A and               Untreated and TreatedTime                Trace Minerals Diluted with Calcium Carbonate (USP               Units/gm)(Wks.) % Trace Mineral Mix               100     97.5    95      90      85@ 45° C. % Calcium Lignin Sulfonates                0       2.5     5      10      15__________________________________________________________________________Initial             889.5                  (100.0%)                       881.5                          (100.0%)                               930.5                                  (100.0%)                                       858.0                                          (100.0%)                                               1,004.0                                                     (100.0%)3                   722.5                  (81.2%)                       816.5                          (92.6%)                               814.0                                  (87.5%)                                       814.0                                          (94.9%)                                               844.0 (84.1%)6                   700.0                  (78.7%)                       763.0                          (86.6%)                               736.5                                  (79.2%)                                       742.0                                          (86.5%)                                               692.0 (68.9%)12                  571.0                  (64.2%)                       696.0                          (79.0%)                               688.0                                  (73.9%)                                       663.0                                          (77.3%)                                               722.5 (72.0%)__________________________________________________________________________ In the above table, the percentages represent percent Vitamin A activity based on initial activity. All data reported in this table are within experimental error. 
    
     EXAMPLE IV 
     In the same manner as carried out in Example I, a trace mineral mix as described in Example I, treated with ammonium lignin sulfonates obtained from Finch, Pruyn &amp; Company (Glens Falls, New York) and used as is, was prepared having a weight ratio of 90% by weight trace minerals and 10% by weight ammonium lignin sulfonates. Sufficient lignin sulfonate product was used to give 10% by weight of lignin sulfonates. The lignin sulfonate had the following composition: 
     
         ______________________________________            % by Weight______________________________________Ammonium lignin sulfonate              45.10Wood sugars        12.90Hemicelluloses and other              41.28carbohydratesAsh                0.72Appearance         Dark LiquidpH                 5.17Solids             49.96Viscosity          60 centipoise @ 20° C.Nitrogen           8.04Specific gravity   1.2251 @  20° C.Total Sulfur       11.49Flash Point        Will not flash below              boiling point of waterSolubility         Completely soluble in water______________________________________ 
    
     After slurrying and drying in a vacuum oven, the treated trace mineral mix was mixed with ground limestone as described in Example II in a weight ratio of 17.8% by weight of trace mineral mix and 82.2% by weight of limestone. The limestone-trace mineral mix was fortified to 1000 USP units of vitamin A per gram with vitamin A palmitate. The vitamin A palmitate was the same as used in Example I. Approximately ten gram portions of the treated trace mineral mixture diluted with limestone and fortified with vitamin A were assayed for vitamin A activity as described in Example I. The remaining materials were placed in capped glass containers and stored in a convection oven at 45° C. At intervals of three, six and twelve weeks, samples were removed and assayed for vitamin A activity using the previously described sample quantities and assay method. The results appear in Table IV. For purposes of comparison with an untreated trace mineral mix diluted with limestone, reference is made to the data set forth in Table II, Columns 2, 3 and 4, which data are repeated in Table IV. 
     
                       TABLE IV______________________________________  Vitamin A Activity of                   Vitamin A Activity of  Mixture of Vitamin A and                   Mixture of Vitamin A and  Untreated Trace Minerals                   Trace Minerals TreatedTime   (Control) diluted with                   with Lignin Sulfonates di-(Wks.) Limestone        luted with Limestone@ 45° C.  (USP Units/gm)   (USP Units/gm)______________________________________Initial  870     886.5   100.0% 883   869.0 100.0%  903                    8553      780     742.0   83.7%  825   803.0 92.4%  704                    7816      679     679.0   76.6%  826   733.0 84.3%  --                     64012     618     562.5   63.4%  681   699.5 80.5%  507                    718______________________________________ In the above table, the percentages represent percent vitamin A activity based on initial activity. All data reported in this table are within experimental error. 
    
     While the invention has been described with reference to certain specific embodiments thereof, it is understood that it is not to be so limited since alterations and changes may be made therein which are within the full intended scope of the appended claims.