Abstract:
A method of improving the quality of egg shells of laying poultry or laying hens without deleterious effects on the contents of the poultry egg shells by adding a small amount of zeolite A to the feed of the poultry.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is in the general field of poultry farming and relates particularly to the feeding of laying fowl or layers. 
     The demand for poultry eggs, especially chicken eggs has expanded considerably over the last decade. The poultry industry has grown from a home industry to a large scale manufacturing industry in which tens of thousand of eggs are produced daily at single farms or egg laying installations. Some eggs are produced for eating and some eggs are produced for hatching. One problem with such large scale egg producing is breakage. Even a slight crack in an egg makes it unsuitable for hatching and most other marketing purposes. It is estimated that some six percent of all eggs produced are lost for marketing because of cracking or breakage. Shell strength is very important to inhibit breakage. The stronger the egg shell, the less likely the egg will be cracked or broken. Machinery and techniques necessary for carefully handling the eggs to avoid breakage are expensive and time consuming. 
     It is therefore an important object of the present invention to provide a means for increasing the strength of the shell of a poultry egg without increasing production costs and without having any deleterious effect on the food value or quality of the egg itself. 
     Another substantial loss of egg production estimated to be about a seven percent loss is the production of shell-less eggs. Any reduction in shell-less eggs can be an important factor in large scale egg production. 
     An article by C. Y. Chung et al from Nongsa Sihom Youngu Pogo 1978, 20 (Livestock) pp. 77-83 discusses the effects of cation exchange capacity and particle size of zeolites on the growth, feed efficiency and feed materials utilizability of broilers or broiling size chickens. Supplementing the feed of the broilers with naturally occurring zeolites, such as clinoptilolite, some increase in body weight gain was determined. Chung et al also reported tha earlier results at the Livestock Experiment Station (1974, 1975, 1976--Suweon, Korea) showed that no significent difference was observed when 1.5, 3, and 4.5 percent zeolite was added to chicken layer diets. 
     U.S. Pat. No. 3,836,676 issued to Chukei Komakine in 1974 discloses the use of zeolites as an adsorbent for adhesion moisture of ferrous sulfate crystals in an odorless chicken feed comprising such crystals and chicken droppings. The results were said to be no less than those in the case where chickens were raised with ordinary feed. 
     Experiments have been in progress in Japan since 1965 on the use of natural zeolite minerals as dietary supplements for poultry, swine and cattle. Significant increases in body weight per unit of feed consumed and in the general health of the animals was reported (Minato, Hideo, Koatsugasu 5:536, 1968). Reductions in malodor were also noted. 
     Using clinoptilolite and mordenite from northern Japan, Onagi, T. (Rept. Yamagata Stock Raising Inst. 7, 1966) found that Leghorn chickens required less food and water and gained as much weight in a two-week trial as birds receiving a control diet. No adverse effects on health or mortality were noted. The foregoing Japanese experiments were reported by F. A. Mumpton and P. H. Fishman in the Journal of Animal Science, Vol. 45, No. 5 (1977) pp. 1188-1203. 
     Canadian Pat. No. 939,186 issued to White et al in 1974 discloses the use of zeolites having exchangeable cations as a feed component in the feeding of urea or biuret non-protein (NPR) compounds to ruminants, such as cattle, sheep and goats. Natural and synthetic as well as crystalline and non-crystalline zeolites are disclosed. Zeolites tested included natural zeolites, chabazite and clinoptilolite and synthetic zeolites X, Y, F, J, M, Z, and A. Zeolite F was by far the most outstanding and zeolite A was substantially ineffective. 
     In a recent study at the University of Georgia, both broilers and layers were fed small amounts (about 2%) of clinoptilolite, a naturally occurring zeolite from Tilden, Tex. The egg shells from the hens receiving zeolite were slightly more flexible as measured by deformation, slightly less strong as measured by Instron breaking strength, and had a slightly lower specific gravity. The differences in egg shell quality were very small. This type of zeolite was ineffective in producing a stronger egg shell. An article written by Larry West and John Shutze entitled &#34;The Influence of Feeding Zeolites to Poultry Under Field Conditions&#34; summarizing the studies was presented at Zeo-Agriculture &#39;82. 
     A study by H. S. Nakaue of feeding White Leghorn layers clinoptilolite, reported in 1981 Poultry Science 60:944-949, disclosed no significant differences in egg shell strength between hens receiving the zeolite and hens not receiving the zeolite. 
     Zeolites are crystalline, hydrated aluminosilicates of alkali and alkaline earth cations, having infinite, three-dimensional structures. 
     Zeolites consist basically of a three-dimensional framework of SiO 4  and AlO 4  tetrahedra. The tetrahedra are cross-linked by the sharing of oxygen atoms so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms is equal to two or O/(Al+Si)=2. The electrovalence of each tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, for example, a sodium ion. This balance may be expressed by the formula Al/Na=1. The spaces between the tetrahedra are occupied by water molecules prior to dehydration. 
     Zeolite A may be distinguished from other zeolites and silicates on the basis of their composition and X-ray powder diffraction patterns and certain physical characteristics. The X-ray patterns for these zeolites are described below. The composition and density are among the characteristics which have been found to be important in identifying these zeolites. 
     The basic formula for all crystalline sodium zeolites may be represented as follows: 
     
         Na.sub.2 O.Al.sub.2 O.sub.3.xSiO.sub.2.yH.sub.2 O. 
    
     In general, a particular crystalline zeolite will have values for &#34;x&#34; and &#34;y&#34; that fall in a definite range. The value &#34;x&#34; for a particular zeolite will vary somewhat since the aluminum atoms and the silicon atoms occupy essentially equivalent positions in the lattice. Minor variations in the relative number of these atoms do not significantly alter the crystal structure or physical properties of the zeolite. For zeolite A, the &#34;x&#34; value normally falls within the range 1.85±0.5. 
     The value for &#34;y&#34; is not necessarily an invariant for all samples of zeolites. This is true because various exchangeable ions are of different size, and, since there is no major change in the crystal lattice dimensions upon ion exchange, the space available in the pores of the zeolite to accommodate water molecules varies. 
     The average value for &#34;y&#34; for zeolite A is 5.1. The formula for zeolite A may be written as follows: 
     
         1.0±0.2Na.sub.2 O.Al.sub.2 O.sub.3.1.85±0.5SiO.sub.2.yH.sub.2 O. 
    
     In the formula, &#34;y&#34; may be any value up to 6. 
     An ideal zeolite A has the following formula: 
     
         (NaAlSiO.sub.4).sub.12.27H.sub.2 O 
    
     Among the ways of identifying zeolites and distinguishing them from other zeolites and other crystalline substances, the X-ray powder diffraction pattern has been found to be a useful tool. In obtaining the X-ray powder diffraction patterns, standard techniques are employed. The radiation is the Kα doublet of copper and a Geiger counter spectrometer with a strip chart pen recorder is used. The peak heights, I, and the positions as a function of 2θ where θ is the Bragg angle, are read from a spectrometer chart. From these, the relative intensities, 100 I/I o , where I o  is the intensity of the strongest line or peak and d the interplanar spacing in angstroms corresponding to the recorded lines are calculated. 
     X-ray powder diffraction data for a sodium zeolite A are given in Table I. 
     
                       TABLE I______________________________________X-RAY DIFFRACTION PATTERN FOR ZEOLITE A                     100 Ih.sup.2 + k.sup.2 + 1.sup.2             d(Å)                     I.sub.o______________________________________ 1                12.29   100 2                8.71    70 3                7.11    35 4                6.15    2 5                5.51    25 6                5.03    2 8                4.36    6 9                4.107   3510                3.895   211                3.714   5013                3.417   1614                3.293   4516                3.078   217                2.987   5518                2.904   1020                2.754   1221                2.688   422                2.626   2024                2.515   625                2.464   426                2.414   &gt;127                2.371   329                2.289   130                2.249   332                2.177   733                2.144   1034                2.113   335                2.083   436                2.053   941                1.924   742                1.901   444                2.858   245                1.837   349                1.759   250                1.743   1353                1.692   654                1.676   255                1.661   257                1.632   459                1.604   6______________________________________ 
    
     The more significant d values for zeolite A are given in Table II. 
     
                       TABLE II______________________________________MOST SIGNIFICANT d VALUES FOR ZEOLITE Ad Value of Reflection in Å______________________________________12.2 ± 0.28.7 ± 0.27.10 ± 0.155.50 ± 0.104.10 ± 0.103.70 ± 0.073.40 ± 0.063.29 ± 0.052.98 ± 0.052.62 ± 0.05______________________________________ 
    
     Occasionally, additional lines not belonging to the pattern for the zeolite appear in a pattern along with the X-ray lines characteristic of that zeolite. This is an indication that one or more additional crystalline materials are mixed with the zeolite in the sample being tested. Small changes in line positions may also occur under these conditions. Such changes in no way hinder the identification of the X-ray patterns as belonging to the zeolite. 
     The particular X-ray technique and/or apparatus employed, the humidity, the temperature, the orientation of the powder crystals and other variables, all of which are well known and understood to those skilled in the art of X-ray crystallography or diffraction can cause some variations in the intensities and positions of the lines. These changes, even in those few instances where they become large, pose no problem to the skilled X-ray crystallographer in establishing identities. Thus, the X-ray data given herein to identify the lattice for a zeolite, are not to exclude those materials which, due to some variable mentioned or otherwise known to those skilled in the art, fail to show all of the lines, or show a few extra ones that are permissible in the cubic system of that zeolite, or show a slight shift in position of the lines, so as to give a slightly larger or smaller lattice parameter. 
     A simpler test described in &#34;American Mineralogist,&#34; Vol. 28, page 545, 1943, permits a quick check of the silicon to aluminum ratio of the zeolite. According to the description of the test, zeolite minerals with a three-dimensional network that contains aluminum and silicon atoms in an atomic ratio of Al/Si=2/3=0.67, or greater, produce a gel when treated with hydrochloric acid. Zeolites having smaller aluminum to silicon ratios disintegrate in the presence of hydrochloric acid and precipitate silica. These tests were developed with natural zeolites and may vary slightly when applied to synthetic types. 
     U.S. Pat. No. 2,882,243 describes a process for making zeolite A comprising preparing a sodium-aluminum-silicate water mixture having an SiO 2  :Al 2  O 3  mole ratio of from 0.5:1 to 1.5:1, and Na 2  O/SiO 2  mole ratio of from 0.8:1 to 3:1, and an H 2  O/Na 2  O mole ratio of from 35:1 to 200:1, maintaining the mixture at a temperature of from 20° C. to 175° C. until zeolite A is formed, and separating the zeolite A from the mother liquor. 
     It is an important object of the present invention to provide an improved feed formulation for laying poultry or layers which contains a small amount of zeolite A. 
     It is a principal object of the invention to provide a poultry feed containing zeolite A which improves the quality of the shell of a poultry egg without causing a deleterious effect on the egg itself. 
     Another object of the invention is to provide an improved process for increasing the strength of egg shells from laying poultry wherein an effective amount of zeolite A is added to the diet of the poultry. 
     Still another object of the invention is to cost effectively increase poultry egg production. 
     Yet a further object of the present invention is to decrease the production of shell-less eggs by laying poultry. 
     Other objects and advantages of the invention will be more fully understood from a reading of the description and claims hereinafter. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method of improving the quality, i.e., the strength of egg shells of layers or laying poultry without deleterious effects on the contents of the egg itself wherein a small amount of zeolite A is added to the feed of the layers, and to a poultry feed composition containing zeolite A. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It has been discovered that the addition of a relatively small amount of zeolite A to a regular or standard feed for laying chickens or hens effectively improves the quality of the egg shell with no significant changes in egg production, egg weight or feed consumption. Zeolite A is preferably added in amounts of from about 0.25 percent to about 4.00 percent of weight of the total feed. 
     A typical feed preparation for large scale laying hen operations comprises the following by weight percent: 
     
         ______________________________________Corn               62-68Soy Bean Meal      18-24Limestone          5-9Alfalfa Meal       1Phosphates         2Sand               1-2Vitamins, Amino Acids              0-1Salt and Other Minerals______________________________________ 
    
     Zeolite A is added to such feed formulation in small amounts by weight percent of up to about four. Greater amounts may be used, but may deprive the layers of the desired amount of nutrients. Greater amounts are also likely to be cost ineffective. A preferred amount of zeolite A is from about one-half to about two percent by weight of the total feed formulation. A most preferred amount of zeolite A is about 0.75 to about 1.50 weight percent of the total feed formulation. 
     The most convenient means of measuring egg shell strength is by measuring the specific gravity of the egg. This is simply done by immersing the egg in solutions of salt water of varying strengths. It is well known in the art that specific gravity correlates with egg shell strength. As specific gravity of the egg is raised, the strength of the egg shell is increased. 
     Using Ethyl EZA® zeolite, a commercially available sodium zeolite A, a number of tests were conducted to determine the effect of zeolite on egg shell quality. 
    
    
     EXAMPLE I 
     Procedure: 480 hens (Dekalb XL pullets) were divided into eight equal groups and fed one of the following dietary treatments for a minimum of six weeks: 
     
         ______________________________________         Calcium  Zeolite ADiet          (wt. %)  (Wt. %)______________________________________1             4.00     02             4.00     0.753             4.00     1.504             4.00      0.68*5             2.75     06             2.75     0.757             2.75     1.508             2.75      0.75**______________________________________ *diet not adjusted for calcium **zeolite added on top except diet not adjusted for Cl 
    
     The diet fed to the hens consisted principally of corn supplemented with a soybean meal (SBM) and limestone. Smaller amounts of alfalfa meal, dicalcium phosphate (DiCalP), a synthetic amino acid (DL-methionine), salt, a commercial vitamin and mineral supplement for layers (Micro-Mix). Sand and/or hydrochloric acid (HCl) were added to some diets. Each diet assured that the hens received all of the required nutrients and minerals. 
     Diets 1-4 contained 1,238 calories per pound, 16% protein, 0.55% total sulfur amino acids, 4% calcium and 0.70% total phosphorous. 
     Diets 5-8 contained 1,292 calories per pound, 16% protein, 0.55% total sulfur amino acids, 2.75% calcium and 0.70% phosphorous. 
     All diets were isocaloric and isonitrogenous within treatments and are detailed in Table A. 
     
                                           TABLE A__________________________________________________________________________      Experimental Diets for Zeolite Study (Weight Percent)      Diet No.      1   2    3    4      5   6    7    8      4.00% calcium        2.75% calciumIngredient 0.0 0.75 1.50 .68 (special)                           0.0 0.75 1.50 0.75__________________________________________________________________________Corn       63.80          63.80               63.80                    63.80  67.83                               67.83                                    67.83                                         67.83SBM        21.41          21.41               21.41                    21.41  20.69                               20.69                                    20.69                                         20.69Alfalfa meal      1.00          1.00 1.00 1.00   1.00                               1.00 1.00 1.00Dicalcium Phosphate      2.07          2.07 2.07 2.07   2.03                               2.03 2.03 2.03Limestone  9.14          9.14 9.14 9.14   5.87                               5.87 5.87 5.87DL-methionine      0.01          0.01 0.01 0.01   --  --   --   --Salt       0.35          0.10 --   0.35   0.35                               0.10 --   0.10Micro-mix  0.50          0.50 0.50 0.50   0.50                               0.50 0.50 0.50Sand       1.72          0.82 --   1.04   1.72                               0.82 --   1.23Zeolite A  --  0.75**               1.50**                    0.68*  --  0.75**                                    1.50**                                         0.75**HCl        --  0.40 0.57 0.00   --  0.40 0.57 --      100.0          100.0               100.0                    100.0  100.0                               100.0                                    100.0                                         100.0__________________________________________________________________________ *0.68 is the special zeolite. (Diet 4) **0.75 and 1.50 is zeolite A. 
    
     Tests criteria were as follows: 
     1. Egg production (weekly) 
     2. Feed consumption (weekly) 
     3. Egg specific gravity (weekly) 
     4. Egg weight (weekly) 
     5. Shell weight (middle and end of experiment) 
     6. Serum calcium at termination 
     7. Body weight at initiation and termination 
     8. Mortality 
     All eggs laid during a 3-day period each week of the experiment and the first week prior to the experiment were used for specific gravity and egg weight measurements. 
     The results are summarized in Tables B, C, D, E, F and G as follows: 
     
                                           TABLE B__________________________________________________________________________EGG SPECIFIC GRAVITY*    No. of                                                Avg. forDiet    Eggs  Week 0          Week 1                Week 2                     Week 3                           Week 4                                Week 5                                      Week 6                                           Week 7                                                Week                                                     8__________________________________________________________________________                                                     Weeks1-4 240   80.24          80.33 80.70                     81.03 80.90                                80.52 78.21                                           80.76                                                80.69                                                     80.395-8 240   80.04          78.69 78.32                     79.15 78.57                                77.75 76.48                                           78.99                                                78.80                                                     78.341 and 5    120   79.88          78.37 77.63                     78.16 77.96                                77.14 75.42                                           77.90                                                77.74                                                     77.542 and 6    120   79.64          79.13 79.47                     79.93 79.83                                79.43 77.20                                           80.10                                                79.51                                                     79.333 and 7    120   80.56          80.60 81.14                     81.59 80.84                                79.87 78.85                                           80.67                                                81.15                                                     80.594 and 8    120   80.47          79.93 79.79                     80.67 80.33                                80.08 77.91                                           80.83                                                80.58                                                     80.011   60    80.27          80.12 79.42                     80.30 79.86                                79.49 77.59                                           79.53                                                79.19                                                     79.442   60    79.70          79.03 80.53                     81.17 81.27                                80.67 78.86                                           81.01                                                81.29                                                     80.483   60    80.35          81.84 81.96                     81.92 81.66                                81.53 79.16                                           81.33                                                81.91                                                     81.444   60    80.64          80.33 80.88                     80.73 80.82                                80.38 77.22                                           81.18                                                80.38                                                     80.245   60    79.50          76.63 75.83                     76.03 76.06                                74.80 73.25                                           76.28                                                76.30                                                     75.656   60    79.60          79.24 78.41                     78.70 78.39                                78.20 75.55                                           79.19                                                77.73                                                     78.177   60    80.77          79.35 80.32                     81.26 80.01                                78.21 78.54                                           80.01                                                80.40                                                     79.768   60    80.31          79.54 78.70                     80.61 79.83                                79.79 78.60                                           80.47                                                80.77                                                     79.79__________________________________________________________________________ *Divide by 1000 and add 1 to convert to Actual Specific Gravity. 
    
     
                                           TABLE C__________________________________________________________________________EGG PRODUCTION (Percent Hen Per Day)    No. of    Percent                                               Avg. forDiet    Calculations        Week 0             Week 1                  Week 2                       Week 3                            Week 4                                 Week 5                                      Week 6                                           Week 7                                                Week                                                     8__________________________________________________________________________                                                     Weeks1-4 240      89.88             86.44                  88.59                       85.10                            87.97                                 87.87                                      87.54                                           86.53                                                84.46                                                     86.815-8 240      90.21             86.59                  84.17                       81.99                            84.65                                 83.45                                      82.84                                           82.58                                                81.82                                                     83.511 and 5    120      90.42             89.25                  88.50                       85.82                            87.86                                 87.74                                      85.48                                           84.82                                                85.25                                                     86.842 and 6    120      90.08             84.55                  86.43                       84.96                            87.13                                 86.46                                      86.69                                           84.67                                                82.71                                                     85.453 and 7    120      89.58             85.12                  85.46                       81.98                            86.32                                 83.93                                      85.02                                           85.65                                                84.22                                                     84.714 and 8    120      90.08             87.14                  85.12                       81.42                            83.93                                 84.52                                      83.57                                           83.09                                                80.36                                                     83.651   60       90.00             90.00                  90.07                       86.19                            90.00                                 88.33                                      86.67                                           84.76                                                87.38                                                     87.932   60       90.00             83.62                  85.95                       85.39                            87.84                                 88.86                                      89.10                                           88.15                                                82.09                                                     86.383   60       89.67             84.76                  88.81                       84.52                            86.90                                 87.38                                      86.77                                           88.46                                                85.27                                                     86.614   60       89.83             87.38                  89.52                       84.28                            87.14                                 86.90                                      87.62                                           84.76                                                83.10                                                     86.345   60       90.83             88.49                  86.91                       85.45                            85.71                                 87.14                                      84.29                                           84.87                                                83.12                                                     85.756   60       90.17             85.48                  86.91                       84.52                            86.43                                 84.04                                      84.29                                           81.19                                                83.33                                                     84.527   60       89.50             85.48                  82.12                       79.44                            85.74                                 80.48                                      83.28                                           82.83                                                83.17                                                     82.828   60       90.33             86.91                  80.72                       78.57                            80.72                                 82.14                                      79.52                                           81.43                                                77.62                                                     80.95__________________________________________________________________________ 
    
     
                       TABLE D______________________________________SHELL WEIGHT (Grams/Egg)    No. of                     Avg. forDiet     Eggs    Week 4      Week 8 8 Weeks______________________________________1-4      240     5.32        5.23   5.285-8      240     5.12        5.08   5.101 and 5  120     5.06        5.06   5.062 and 6  120     5.22        5.14   5.183 and 7  120     5.31        5.23   5.274 and 8  120     5.29        5.19   5.241        60      5.23        5.20   5.222        60      5.37        5.27   5.323        60      5.40        5.29   5.354        60      5.29        5.18   5.245        60      4.89        4.93   4.916        60      5.08        5.00   5.047        60      5.21        5.17   5.198        60      5.29        5.21   5.25______________________________________ 
    
     
                                           TABLE E__________________________________________________________________________FEED CONSUMPTION (Grams Per Hen Per Day)    No. of                                        Avg. forDiet    Weighings     Week 1          Week 2               Week 3                    Week 4                         Week 5                              Week 6                                   Week 7                                        Week 8                                             8 Weeks__________________________________________________________________________1-4 240   105.48          108.16               109.76                    110.13                         112.85                              105.64                                   110.57                                        115.53                                             109.765-8 240   103.91          101.62               106.01                     96.66                         107.96                              103.42                                   107.12                                        112.09                                             104.851 and 5    120   112.06          105.92               109.32                    107.44                         112.54                              106.08                                   110.57                                        116.80                                             110.092 and 6    120   101.85          104.96               107.04                    105.92                         109.13                              102.66                                   108.82                                        113.69                                             106.763 and 7    120   102.08          105.07               107.99                    101.47                         110.17                              105.25                                   109.16                                        112.40                                             106.704 and 8    120   102.78          103.60               107.20                     98.76                         109.76                              104.12                                   106.84                                        112.35                                             105.671   60    113.25          109.55               112.98                    115.07                         117.42                              106.76                                   113.94                                        119.90                                             113.612   60     99.45          106.05               107.28                    110.78                         111.20                              102.75                                   109.22                                        113.21                                             107.493   60    104.65          109.60               111.13                    108.85                         111.98                              107.66                                   110.73                                        115.78                                             110.054   60    104.56          107.43               107.65                    105.82                         110.78                              105.38                                   108.40                                        113.21                                             107.905   60    110.86          102.30               105.65                     99.81                         107.65                              105.41                                   107.21                                        113.69                                             106.576   60    104.24          103.88               106.80                    101.05                         107.07                              102.57                                   108.42                                        114.16                                             106.027   60     99.52          100.53               104.85                     94.08                         108.37                              102.83                                   107.59                                        109.03                                             103.358   60    101.01           99.77               106.75                     91.70                         108.74                              102.87                                   105.28                                        111.48                                             103.45__________________________________________________________________________ 
    
     
                       TABLE F______________________________________BODY WEIGHT (Grams per Hen)   No. ofDiet    Weighings      Week 0   Week 1______________________________________1-4     240            1,538.58 1,550.635-8     240            1,518.58 1,520.001 and 5 120            1,526.25 1,565.002 and 6 120            1,528.00 1,542.003 and 7 120            1,515.58 1,492.004 and 8 120            1,544.50 1,542.251       60             1,541.67 1,579.332       60             1,525.83 1,543.173       60             1,518.67 1,507.004       60             1,508.17 1,573.005       60             1,510.83 1,550.676       60             1,530.17 1,540.837       60             1,512.50 1,477.008       60             1,520.83 1,511.50______________________________________ 
    
     
                                           TABLE G__________________________________________________________________________EGG WEIGHTS (Grams per Egg)    No. of                                                Avg. forDiet    Weighings     Week 0           Week 1                Week 2                     Week 3                          Week 4                                Week 5                                     Week 6                                          Week 7                                                Week                                                     8__________________________________________________________________________                                                     Weeks1-4 240   59.04 59.87                59.98                     60.06                          60.33 59.95                                     59.88                                          60.19 60.19                                                     60.055-8 240   58.85 59.38                59.45                     59.59                          59.84 59.81                                     59.51                                          59.60 59.97                                                     59.641 and 5    120   58.58 59.12                59.49                     59.53                          59.64 59.77                                     59.59                                          60.14 60.22                                                     59.692 and 6    120   58.93 59.96                59.91                     59.84                          60.13 59.88                                     59.64                                          59.97 60.09                                                     59.933 and 7    120   58.95 59.72                59.80                     59.86                          60.26 59.77                                     59.81                                          59.72 60.01                                                     59.874 and 8    120   59.31 59.69                59.67                     60.06                          60.31 60.08                                     59.73                                          59.76 59.99                                                     59.911   60    58.74 59.66                60.03                     60.03                          60.03 59.81                                     60.13                                          60.70 60.77                                                     60.182   60    59.21 60.28                59.98                     60.05                          60.37 60.56                                     59.93                                          60.39 60.23                                                     60.223   60    58.94 59.62                60.26                     60.00                          60.57 59.56                                     59.92                                          59.88 60.13                                                     59.994   60    59.26 59.92                59.66                     60.17                          60.05 59.85                                     59.54                                          59.78 59.61                                                     59.825   60    58.42 58.59                58.95                     59.03                          58.95 59.73                                     59.04                                          59.58 59.66                                                     59.196   60    58.66 59.64                59.84                     59.64                          59.90 59.20                                     59.34                                          59.54 59.96                                                     59.637   60    58.96 59.83                59.34                     59.72                          59.95 59.97                                     59.71                                          59.56 59.89                                                     59.758   60    59.35 59.46                59.70                     59.96                          60.56 60.32                                     59.93                                          59.75 60.36                                                     60.01__________________________________________________________________________ 
    
     A review of the test data in Table B shows that zeolite A provided a definite benefit on shell quality, and had no significant effect on the other qualities studied except possibly for shell weight. Two concentrations (0.75%, 1.5%) were evaluated because of sodium limitations and for those levels, the data showed a linear relationship with concentration. 
     In Table C zeolite A had no significant effect on production (% hen day). However there is some indication that a slight reduction occurred, particularly with Diet 8 in the 2.75% Ca series (i.e. low-Ca). 
     In Table D there appears to be an indication of some benefits from zeolite A. 
     Previous indications that feed consumption was reduced without any reduction in egg or body weight or in egg production could not be substantiated by the statistical data. As shown in Table E 1.5% zeolite A reduced feed consumption, relative to baseline, at both Ca levels in Weeks 1 and 4. However this did not occur in the other six weeks of the trial. Thus if we look at the results for the 8th week: 
     
         ______________________________________% Ca       Run No.  Feed Cons. (g/hen/day)______________________________________2.75       1        113.692.75       2        114.162.75       3        109.032.75       4        111.48______________________________________ 
    
     The reduced value is most likely attributable to a palatability consideration. Laying hens usually eat more than they need. Any factor, such as feed dustiness, can reduce intake by up to 5% without an adverse effect. 
     Tables F and G show no significant benefits for body and egg weights. 
     EXAMPLE II 
     Procedure: 480 hens were divided into eight equal groups and fed one of the following dietary treatments for a minimum of three months. 
     
         ______________________________________         TSAA     Zeolite ADiet          (Wt. %)  (Wt. %)______________________________________ 9            0.51     010            0.51     0.7511            0.51     1.5012            0.51      0.68*13            0.61     014            0.61     0.7515            0.61     1.5016            0.61      0.68*______________________________________ *special zeolite  10.43% Ca and 0.52% Na. 
    
     All diets were isocaloric and isonitrogenous and are detailed in Table H. 
     Tests criteria were the same as in Example I. 
     The components of the diets were also similar as those of Example I. 
     Diets 9-12 contained 1237 calories per pound, 17% protein, 0.61% TSAA (Total Sulphur Amino Acids), 3.75% calcium and 0.70% phosphorus. 
     Diets 13-16 contained 1262 calories per pound, 14.78% protein, 0.51% TSAA, 3.75% calcium and 0.70% phosphorus. 
     
                                           TABLE H__________________________________________________________________________          Experiment Diets for Zeolite Study (Weight Percent)          Diet No.          9   10  11  12     13  14  15  16          0.51% TSAA         0.61% TSAAIngredient Name          0.00%              0.75%                  1.50%                      0.68 (special)                             0.00%                                 0.75%                                     1.50%                                         0.68 (special)__________________________________________________________________________Corn           67.65              67.65                  67.65                      67.65  62.07                                 62.07                                     62.07                                         62.07SBM (48%)      18.19              18.19                  18.19                      18.19  23.81                                 23.81                                     23.81                                         23.81Alfalfa (17%)  1.00              1.00                  1.00                      1.00   1.00                                 1.00                                     1.00                                         1.00Dicalcium Phosphate (18.5%)          2.12              2.12                  2.12                      2.12   2.01                                 2.01                                     2.01                                         2.01Limestone      8.47              8.47                  8.47                      8.29   8.50                                 8.50                                     8.50                                         8.31DL-methionine  --  --  --  --     0.04                                 0.04                                     0.04                                         0.04Salt           0.35              0.10                  --  0.35   0.35                                 0.10                                     --  0.35Micro-mix      0.50              0.50                  0.50                      0.50   0.50                                 0.50                                     0.50                                         0.50Sand           1.72              0.82                  --  1.22   1.72                                 0.82                                     --  1.23Zeolite        --  0.75                  1.50                      0.68   --  0.75                                     1.50                                         0.68HCl             -- 0.40                  0.57                      --     --  0.40                                     0.57                                         --TOTAL          100.0              100.0                  100.0                      100.0  100.0                                 100.0                                     100.0                                         100.0__________________________________________________________________________ 
    
     The results of the tests are summarized in Tables P, J, K, L, M, and N. 
     
                                           TABLE P__________________________________________________________________________EGG SPECIFIC GRAVITY*No. of                                      Avg. forDiet Eggs    Week 0         Week 1              Week 2                   Week 3                        Week 4                             Week 6                                  Week 7                                       Week 8                                            8 Weeks__________________________________________________________________________ 9-12240 89.24         90.54              88.87                   88.53                        90.05                             87.80                                  88.47                                       87.18                                            88.3413-16240 89.86         91.24              88.84                   89.30                        90.19                             88.38                                  88.06                                       87.87                                            89.22 9 and 13120 89.34         89.93              87.90                   87.94                        88.88                             86.81                                  87.67                                       86.66                                            88.1410 and 14120 89.38         90.85              89.01                   88.60                        89.93                             88.25                                  88.43                                       87.03                                            88.9411 and 15120 90.44         92.07              90.13                   90.01                        91.29                             89.40                                  88.88                                       88.57                                            90.1012 and 16120 89.06         90.71              88.40                   89.11                        90.40                             87.89                                  88.06                                       87.84                                            88.93 9   60  89.27         89.25              87.83                   87.46                        88.36                             86.14                                  88.09                                       86.49                                            87.8610   60  89.16         90.89              89.76                   87.78                        90.48                             88.08                                  88.68                                       86.40                                            88.9011   60  90.04         91.73              89.92                   90.00                        91.23                             89.27                                  89.07                                       88.07                                            88.9212   60  88.50         90.31              87.99                   88.89                        90.16                             87.71                                  88.04                                       87.78                                            88.6713   60  89.41         90.61              87.97                   88.43                        89.39                             87.48                                  87.24                                       86.83                                            88.4214   60  89.60         90.81              88.27                   89.41                        89.39                             88.41                                  88.21                                       87.66                                            88.9715   60  90.83         92.41              90.33                   90.02                        91.35                             89.53                                  88.69                                       89.07                                            90.2816   60  89.62         92.12              88.80                   89.33                        90.64                             88.08                                  88.09                                       87.91                                            89.20__________________________________________________________________________ *Divide by 1000 and add 1 to convert to Actual Specific Gravity. 
    
     
                                           TABLE J__________________________________________________________________________EGG PRODUCTION (Percent Hen Per Day)No. of                                        Avg.Percent                                       forCalcula-  Week No.                            12Diet tions     1  2  3  4  5  6  7  8  9  10 11 12 Weeks__________________________________________________________________________ 9-12240  57.26        69.54           78.04              80.82                 84.93                    87.00                       85.83                          89.24                             88.33                                87.81                                   81.55                                      87.87                                         81.5213-16240  53.41        69.40           81.83              87.13                 89.39                    89.92                       89.18                          89.92                             87.53                                88.76                                   84.13                                      88.24                                         83.24 9 and 13120  53.73        71.31           82.12              85.19                 87.94                    87.86                       86.34                          89.48                             89.22                                87.63                                   82.06                                      85.29                                         82.3510 and 14120  60.23        71.31           75.71              76.47                 82.74                    89.22                       89.52                          91.19                             88.69                                90.12                                   86.19                                      90.60                                         82.5811 and 15120  51.93        64.32           78.01              85.01                 87.65                    89.17                       85.76                          88.61                             86.73                                88.86                                   83.31                                      87.59                                         81.4112 and 16120  55.43        70.95           83.89              89.25                 90.31                    88.60                       88.40                          89.04                             87.06                                86.52                                   79.79                                      88.74                                         83.16 9   60   55.00        70.48           80.24              81.67                 85.48                    87.14                       82.86                          88.34                             88.81                                87.14                                   77.82                                      84.76                                         80.7910   60   60.95        70.95           70.48              67.86                 76.43                    85.24                       88.34                          91.43                             89.76                                89.29                                   85.48                                      89.76                                         80.5011   60   56.72        70.08           81.75              87.88                 88.15                    88.18                       83.41                          87.94                             87.04                                88.92                                   83.28                                      89.57                                         82.5712   60   56.35        66.67           79.68              85.87                 89.66                    87.43                       88.71                          89.26                             87.70                                85.90                                   79.81                                      89.39                                         82.2013   60   52.46        72.14           83.99              88.71                 90.40                    88.57                       89.82                          90.63                             89.63                                88.12                                   86.51                                      85.82                                         83.9014   60   59.53        71.67           80.95              85.07                 89.05                    91.19                       90.71                          90.95                             87.62                                90.95                                   86.91                                      91.43                                         84.6715   60   47.14        58.57           74.28              82.14                 87.14                    90.17                       88.10                          89.29                             86.43                                88.81                                   83.33                                      87.62                                         80.2516   60   54.52        75.24           88.10              92.62                 90.95                    89.76                       88.10                          88.81                             86.43                                87.15                                   79.76                                      88.10                                         84.13__________________________________________________________________________ 
    
     
                       TABLE K______________________________________SHELL WEIGHT (Grams/Egg)     No. of                    Avg. forDiet      Eggs    Week 1     Week 2 2 Weeks______________________________________ 9-12     240     5.58       5.54   5.5613-16     240     5.67       5.63   5.65 9 and 13 120     5.52       5.60   5.5610 and 14 120     5.59       5.55   5.5711 and 15 120     5.68       5.60   5.6412 and 16 120     5.70       5.59   5.65 9        60      5.45       5.54   5.4910        60      5.60       5.54   5.5711        60      5.63       5.53   5.5812        60      5.64       5.54   5.5913        60      5.60       5.65   5.6214        60      5.59       5.56   5.5715        60      5.73       5.64   5.7016        60      5.76       5.64   5.70______________________________________ 
    
     
                                           TABLE L__________________________________________________________________________FEED CONSUMPTION (Grams Per Hen Per Day)No. ofWeigh-   Week             Week                 Week                     Week                         Week                             Week                                 Week                                     Week                                         Week                                             Week                                                 WeekDiet ings    Week 1         2   3   4   5   6   7   8   9   10  11  12  12__________________________________________________________________________                                                     Weeks 9-12240 48.46         99.99             109.73                 119.50                     122.02                         124.81                             121.58                                 120.55                                     119.90                                         116.19                                             127.07                                                 126.87                                                     113.0613-16240 46.83         99.44             108.18                 115.65                     117.85                         120.77                             118.26                                 118.37                                     118.88                                         115.16                                             123.32                                                 127.25                                                     110.89 9 and 13120 50.38         102.66             111.29                 119.56                     122.97                         122.55                             121.86                                 120.09                                     119.88                                         114.09                                             126.58                                                 127.97                                                     113.4110 and 14120 51.39         97.54             106.64                 115.63                     121.17                         123.85                             120.33                                 120.67                                     120.22                                         117.38                                             127.20                                                 128.18                                                     112.5211 and 15120 40.78         95.91             106.74                 116.19                     116.49                         120.14                             115.64                                 115.23                                     115.71                                         112.91                                             123.17                                                 123.68                                                     108.5512 and 16120 48.02         102.77             111.14                 118.91                     119.03                         124.61                             121.86                                 121.83                                     121.32                                         117.33                                             125.82                                                 128.41                                                     113.42 9   60  55.36         107.40             116.61                 123.85                     126.99                         124.25                             126.59                                 124.45                                     121.78                                         115.12                                             127.93                                                 129.53                                                     116.6610   60  50.04         94.97             102.57                 115.92                     121.49                         126.62                             122.74                                 123.44                                     122.81                                         118.76                                             130.94                                                 129.54                                                     113.3211   60  41.59         96.84             109.08                 117.39                     116.79                         120.14                             225.64                                 113.21                                     115.28                                         111.69                                             123.85                                                 121.46                                                     108.5812   60  46.84         100.76             110.66                 120.83                     122.83                         128.23                             121.34                                 121.08                                     119.75                                         119.21                                             125.55                                                 126.94                                                     113.6713   60  45.40         97.91             105.97                 115.27                     118.95                         120.85                             117.12                                 115.74                                     117.97                                         115.06                                             125.23                                                 126.42                                                     110.1614   60  52.74         100.10             110.72                 115.33                     121.04                         121.08                             117.92                                 117.90                                     117.63                                         115.99                                             123.47                                                 126.82                                                     111.7315   60  40.00         94.98             104.39                 115.00                     116.20                         120.14                             115.63                                 117.25                                     116.14                                         114.14                                             122.50                                                 125.90                                                     108.5216   60  49.20         104.78             111.62                 116.99                     115.22                         121.00                             122.39                                 122.58                                     122.90                                         115.46                                             126.08                                                 129.88                                                     113.17__________________________________________________________________________ 
    
     
                       TABLE M______________________________________BODY WEIGHT (Grams per Hen)         No. ofDiet No.      Weighings Difference______________________________________ 9-12         240       218.0013-16         240       219.46 9 and 13     120       228.2510 and 14     120       219.5011 and 15     120       205.3312 and 16     120       221.83 9            60        239.5010            60        228.3311            60        179.6712            60        224.5013            60        217.0014            60        210.6715            60        231.0016            60        219.17______________________________________ 
    
     
                                           TABLE N__________________________________________________________________________EGG WEIGHTS (Grams per Egg)No. of                                        Avg. forDiet Weighings      1 Week           2 Weeks                3 Weeks                     4 Weeks                          6 Weeks                               8 Weeks                                    10 Weeks                                         12 Weeks                                              12 Weeks__________________________________________________________________________ 9-12240   51.42           51.86                53.42                     54.07                          55.48                               56.49                                    57.57                                         58.72                                              58.8813-16240   52.57           53.90                55.04                     55.94                          57.21                               57.88                                    58.79                                         59.82                                              56.39 9 and 13120   52.05           53.10                54.82                     55.18                          56.38                               57.19                                    58.35                                         59.30                                              55.8010 and 14120   52.24           52.38                53.18                     54.36                          56.24                               57.29                                    58.37                                         59.29                                              55.4211 and 15120   51.28           52.31                54.13                     55.04                          56.18                               56.87                                    57.53                                         59.00                                              55.2912 and 16120   52.43           53.73                54.78                     55.45                          56.59                               57.39                                    58.48                                         59.48                                              56.03 9   60    51.30           52.08                54.25                     54.49                          55.39                               56.71                                    57.71                                         59.08                                              55.1110   60    51.72           51.05                52.06                     53.10                          55.54                               57.00                                    58.01                                         59.20                                              54.7911   60    51.31           51.81                53.95                     54.35                          55.38                               56.09                                    56.65                                         58.38                                              54.7412   60    51.36           52.50                53.51                     54.36                          55.62                               56.18                                    57.91                                         58.21                                              54.9613   60    52.79           54.11                55.49                     55.87                          57.37                               57.68                                    58.99                                         59.53                                              56.4814   60    52.76           53.71                54.30                     55.62                          56.93                               57.58                                    58.74                                         59.37                                              56.1315   60    51.25           52.82                54.32                     55.74                          56.98                               57.64                                    58.41                                         59.62                                              55.8516   60    53.51           54.96                56.05                     56.53                           57.566                               58.60                                    59.04                                         60.75                                              57.12__________________________________________________________________________ 
    
     A review of the test data in Tables P and J through N shows that substantially the same results were obtained as those in Tables B through H. 
     In a preliminary study of a relatively few laying hens with one percent zeolite in the diet it was indicated that the relative ranks of zeolites in improving shell strength were as follows: 
     
         ______________________________________Rank            Shell Strength______________________________________1               Zeolite A2               Synthetic Mordenites3               Synthetic Zeolite X4               Natural Erionite5               Natural Clinoptilolite6               Synthetic Zeolite Y______________________________________ 
    
     In shell strength, the controls were inferior to or equal to the poorest of all the zeolites. 
     The later studies clearly show that zeolite A is effective in increasing shell strength. Some increase in shell strength using mordenite should also be expected. 
     The term poultry includes all domestic fowl, namely chickens, turkeys, ducks, geese, and the like. 
     Corn is the principal diet for most laying poultry. A feed formulation comprising by weight percent the following is desirable: 
     
         ______________________________________         Weight Percent______________________________________corn            50-75soybean meal    10-30calcium carbonate            4-10zeolite A       0.25-4.0______________________________________ 
    
     Calcium carbonate is usually in the form of natural limestone ground to a suitable particle size, but sometimes oyster shells which have also been suitably ground are used. 
     It can be appreciated that a wide variety of nutrients or foods may be included in the diets of layers or poultry laying hens. In a controlled environment, the hens are only exposed to desired foods or food products. A typical laying ration composition contains the following: 
     
         ______________________________________              Weight Percent______________________________________crude protein not less than                    16.0crude fat     not less than                    2.5crude fiber   not more than                    7.0calcium (as Ca)         not less than                    3.1calcium (as Ca)         not more than                    4.1phosphorus (P)         not less than                    0.5iodine (I)    not less than                      0.0001salt (NaCl)   not less than                    0.3salt (NaCl)   not more than                    0.9______________________________________ 
    
     The foregoing composition is obtained from or included the following ingredients: 
     Grain and processed grain by-products. Includes corn, corn hominy, corn germ meal, barley, millet, oats, rice, rice hulls, rye, sorghum, wheat and wheat shorts. These are among the energy ingredients, mostly carbohydrates with some proteins. 
     Plant protein products. Includes soybean oil meal, barley malt sprouts, coconut meal, corn distillers grain, corn gluten meal, cottonseed meal, pea seed, potato meal, peanut meal, rape seed meal, sunflower meal, wheat germ meal, brewers&#39; yeast. All of these are protein sources. 
     Roughage or fiber. Includes dehydrated alfalfa, alfalfa hay, alfalfa leaf meal and pasture grasses. These are all fiber sources. 
     Animal and fish by-products. Includes blood meal, blood flour, dried buttermilk, dried whey, dried casein, fish meal, dried fish solubles, liver meal, meat meal, meat meal tankage, bone meal and dried skim milk. Anchovies, herring and menhaden are sources of fish meal. 
     Minerals and synthetic trace ingredients. Includes vitamins such as B-12, A, pantothenate, niacin, riboflavin, K, etc., DL methionine, choline chloride, folic acid, dicalcium phosphate, magnesium sulfonate, potassium sulfate, calcium carbonate (limestone, oyster shells), salt, sodium selenite, manganous oxide, calcium iodate, copper oxide, zinc oxide and D activated animal sterol. 
     Molasses and animal fats are added to improve palatability and to increase or balance the energy levels. 
     Preservatives are also added such as, Ethoxyquin™ and sodium sulfite. 
     In general, a feed composition for poultry laying hens should preferably contain by weight percent the following: 
     
         ______________________________________               Weight Percent______________________________________crude protein       at least about                     14crude fat   at least about                     2crude fiber not more than about                     7calcium     about         2.7 to 4.1phosphorous at least about                     0.05iodine      at least      0.0001sodium      about         0.1 to 0.4chlorine    about         0.1 to 0.5zeolite A   about         0.25 to 4.0______________________________________ 
    
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the illustrated process may be made within the scope of the appended claims without departing from the spirit of the invention.