Treatment of tibial dyschondroplasia
This is a continuation of Ser. No. 07/311,540 filed Feb. 16, 1989, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to the field of veterinary science, and is in particular a method for reducing the incidence of tibial dyschondroplasia in animals. 
     The federal government has rights in this invention by virtue of the fact that it partially funded the experimentation which lead to the discovery of this invention. 
     Tibial dyschondroplasia is a skeletal abnormality which occurs in rapidly growing animals such as broiler chickens or turkeys. The abnormality is characterized by an unmineralized, unvascularized mass of cartilage located in the proximal ends of the tibiotarsus and the tarsusmetatarsus. The cartilage extends from the growth plate into the metaphysis. In fowl, tibial dyschondroplasia usually appears between three and eight weeks of age. 
     In some chickens and turkeys, the prehypertrophic cartilage persists into adulthood and is restricted to the posterior medial portion of the proximal tibiotarsal bone, and the birds remain clinically normal. An incidence of 10 to 30% of birds with subclinical dyschondroplasia is common in many flocks. In the more severe cases of tibial dyschondroplasia, the abnormal tissue occupies the whole metaphysis of the proximal tibiotarsal bone and also develops in the proximal tarsometatarsal bone. Birds with these more severe lesions may be lame, with bowing of the affected bones. These chickens can have difficulty walking and are prone to falling down, causing injury and decreasing growth rate. The disease also increases the death rate of animals during the growth period. Further, many of the birds suffering from the disease develop breast blisters and leg deformities that result in hemorrhages. 
     Tibial dyschondroplasia increases the percentage of carcasses downgraded or condemned in processing plants, which results in decreased profits for the processor. When flocks of birds have a high incidence of tibial dyschondroplasia, the crooked legs can interfere with the shackling of the fowl during processing and can actually cause mechanical problems in operating the processing line where the slaughtered fowl are conveyed on machines which handle the birds by their legs. Fowl with tibial dyschondroplasia have insufficient leg strength to be carried in this manner. 
     A number of studies have been conducted to determine both the cause of dyschondroplasia and a method for treatment or prevention. Leach and Nesheim, &#34;Further Studies on Tibial Dyschondroplasia Cartilage Abnormality in Young Chicks&#34;, J. Nutr. 102, 1673 (1972), indicated that the cartilage abnormality is a result of an inherited physiological defect, the expression of which is under dietary control. They were not able to determine the nutritional factors responsible for expression. However, they found that manipulations of the mineral mixture that resulted in changes in acid/base or cation/anion balance in the chick altered the incidence of abnormality. In particular, high chloride level in the diet increased the incidence of the abnormality when chicks were fed diets similar to those used commercially. 
     Mongin and Sauveur, in &#34;Interrelationship Between Mineral Nutrition, Acid-Based Balance, Growth and Cartilage Abnormalities,&#34; Growth and Poultry Meat Production, Borman, K. N. and Wilson, B. J., Eds., pp. 235-247, British Poultry Science Ltd., Edinburgh, Scotland (1977), hypothesized that the metabolic acidosis in chickens fed high dietary chloride levels caused tibial dyschondroplasia because of impaired bone mineralization resulting from alteration of vitamin D metabolism. 
     Chickens made acidotic by administration of ammonium chloride show reduced conversion of 25(OH)D 3  to 1,25(OH) 2  D 3 , although the production of 24,25-dihydroxycholecalciferol (24,25(OH) 2  D 3 ) from 25(OH)D 3  was not consistently affected by acidosis, as also reported by Sauveur and Mongin, in &#34;Influence of Dietary Level of Chloride, Sodium and Potassium on Chick Cartilage Abnormalities,&#34; Proceedings of XV World Poultry Congress, pp. 180-181 (1977). 
     However, supplementation of chickens with 20 ng/day of either 1,25-dihydroxycholecalciferol (1,25(OH) 2  D 3 ) or 24,25-dihydroxycholecalciferol (24,25(OH) 2  D 3 ) was demonstrated to have no effect on the incidence of tibial dyschondroplasia, as described by Edwards in &#34;Studies on the Etiology of Tibial Dyschondroplasia in Chickens&#34;, J. Nutr., 114, 1001 (1984). 
     Calcium and phosphorus levels in the diet have been found to be major nutritional factors influencing the expression of tibial dyschondroplasia. High calcium in the feed retards the development of the lesion, whereas high phosphorus levels appear to accentuate the development of the lesions, as reported by Edwards and Veltmann, &#34;The Role of Calcium and Phosphorus in the Etiology of Tibial Dyschondroplasia in Young Chicks,&#34; J. Nutr., 113, 1568 (1983). 
     Increases in the magnesium content of the chick diet decrease the incidence of tibial dyschondroplasia; however, the effect of magnesium is not as strong as that of calcium, as demonstrated by Edwards, &#34;Studies on the Etiology of Tibial Dyschondroplasia in Chickens&#34;, J. Nutr., 114, 1001 (1984). 
     Given the large economic loss to meat producers caused by animals afflicted with tibial dyschondroplasia as well as the discomfort of the afflicted animal and the resulting unsanitary conditions caused by the diseased dysfunctional animal, it would be of great benefit to find an effective method and compositions to reduce the incidence of this disease. 
     It is therefore an object of the present invention to provide a method and compositions for the treatment and prevention of tibial dyschondroplasia in animals. 
     It is another object of the present invention to provide compositions which may be administered economically and easily to animals to reduce the incidence of tibial dyschondroplasia. 
     SUMMARY OF THE INVENTION 
     The objects of the present invention described above are achieved with a method and compositions for the treatment and prevention of tibial dyschondroplasia in animals, particularly fowl. 
     The method includes administering to animals a composition delivering an effective amount of 1,25-dihydroxycholecalciferol, 1,25-dihydroxy-26,27-hexadeuterocholecalciferol, 1-hydroxycholecalciferol, 1,24,25-trihydroxycholecalciferol, 1,25-dihydroxy-24-fluorocholecalciferol, 25-hydroxycholecalciferol, or combinations thereof, in a pharmaceutically acceptable carrier. 
     These compositions may be administered to animals orally, subcutaneously, intramuscularly, intravenously or intraperitoneally. For example, it may be given in a feed composition, the water supply, by time or slow-release bolus or other controlled drug delivery device, an orally administered capsule, or by an injection. 
     The effectiveness of the method of the present invention in reducing the incidence of tibial dyschondroplasia, can be enhanced by administering the vitamin D 3  derivatives in combination with an effective amount of vitamin D 3 . 
     In the preferred embodiment for prevention of tibial dyschondroplasia in poultry, a composition is administered which delivers a dosage of between approximately 0.1 and 20 micrograms of vitamin D 3  derivative per day. The administration preferably is initiated on the first day of life and is continued for at least three weeks. 
     Tibial dyschondroplasia already established in poultry can be treated according to the method of the present invention by administering a composition which delivers a dosage of between 0.1 and 20 micrograms per day. The treatment is initiated as soon as the disease is discovered and continued until cured. 
     In the preferred embodiment for prevention or treatment of tibial dyschondroplasia in other animals, a composition is administered which delivers a dosage of at least 1 microgram per day per kilogram of weight. The treatment should be initiated at birth and continued throughout the animal&#39;s rapid growth stage. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is an illustration of the chemical structures of vitamin D 3  (cholecalciferol) (1), 1,25-dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24-fluorocholecalciferol (6), and 25-hydroxycholecalciferol (7), as used in the method and compositions of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a method and compositions to treat and prevent tibial dyschondroplasia in animals. Reduction in the incidence of tibial dyschondroplasia improves the health of the animals treated and the sanitary conditions of the animal facility. It also allows more chickens and turkeys to be successfully processed before and after slaughter, thereby reducing costs to the processor. 
     Referring to FIG. 1, the method includes administering to animals a composition which delivers an effective amount of the vitamin D 3  derivative 1,25-dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24-fluorocholecalciferol (6), or 25-hydroxycholecalciferol (7) to reduce or reverse the development of abnormal cartilage at the proximal end of the tibia. 
     Although described with specific reference to chickens and turkeys, the method and compositions are equally effective in the treatment of other types of animals, including but not limited to pheasant, ducks, swine, dogs, rabbits, cattle, and fish. For example, Great Danes have a particular problem with tibial dyschondroplasia due to their rapid growth. Administration of the above described compositions according to the method described here should be efficacious in reducing the incidence of the disease in these animals. 
     Effective Dosage Range 
     In contrast to the previous reports by Edwards in &#34;Studies on the Etiology of Tibial Dyschondroplasia in Chickens&#34;, J. Nutr.. 114, 1001 (1984), that administration to chickens of 20 ng/day of either 1,25-dihydroxycholecalciferol (1,25(OH) 2  D 3 ) or 24,25-dihydroxycholecalciferol (24,25(OH) 2  D 3 ) has no effect on the incidence of tibial dyschondroplasia, it has now been discovered that administration to chickens of certain vitamin D 3  derivatives in a dosage range of between approximately 0.1-20 g of vitamin D 3  derivative per day from one day old to three weeks of age causes a significant reduction of the incidence of tibial dyschondroplasia. 
     In particular, the incidence of tibial dyschondroplasia in fowl can be lowered by administering daily dosages of vitamin D 3  compound in the range of about 0.2 micrograms (μg) per day per bird for a 1 week old bird to about 2 g per day per bird for an 8 week old bird. 
     An effective dosage for prevention of tibial dyschondroplasia in animals other than fowl is at least 1 microgram of vitamin D 3  derivative per day per kilogram of body weight. This dosage results in normal calcification and shaping of bones as well as preventing the disease. The treatment should preferably be started at birth and continued throughout the period of rapid growth. It can be continued for the life of the animal. For example, in poultry, treatment is preferably begun at one day of age, and continued for at least three to four weeks. 
     Administration of the vitamin D 3  derivatives of the present invention later than one day of age will still provide a therapeutic effect, but will be slightly less effective at preventing the onset of the disease. 
     The compositions of the present invention can also be administered as a treatment for tibial dyschondroplasia already established in the animal. The same dosages are used as for prevention of the disease. The administration of the compositions should begin as soon as the disease is discovered, and continued until the animal is cured. However, administration of the compositions will not reverse the abnormal shape of bones caused by the disease. 
     The effectiveness of administration of the compositions of the present invention on prevention or treatment of tibial dyschondroplasia in fowl can be determined by making a longitudinal cut across the tibia and inspecting for incidence and severity of the disease, as described in the Example of Treatment of Tibial Dyschondroplasia. 
     The effectiveness of administration of the compositions delivering the vitamin D 3  derivatives on prevention or treatment of dyschondroplasia in other animals can be determined by internal inspection of the bone for abnormal cartilage development or external inspection of bone for irregularities, bowed shape, or weakness. 
     Method for Administration 
     For poultry, a suitable and easy means of administration of the compounds of the present invention is to include them in bird feed at a dosage range of between approximately 5 and 20 micrograms per kilogram of bird feed. A starter feed given to chickens in the first two weeks of life can be mixed with the vitamin D 3  derivative at a ratio of 10-20 μg of compound per kg of feed. The grower feed given to chickens in the next two weeks of life may contain 5-10 μg of compound per kg of feed and the finisher feed given to chickens in their last weeks of life may contain up to 5 g of compound per kg of feed. The amount of compound in the feed is decreased over time to take into account the increased feed intake of the animal as it grows. This allows the producer to use cheaper feed for the older bird. 
     Vitamin D 3  in Combination with Vitamin D 3  Derivatives 
     1,25-Dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24-fluorocholecalciferol (6) or 25-hydroxycholecalciferol (7), can be administered in combination with vitamin D 3  to insure a healthy animal. Animals, including poultry, should normally be given adequate vitamin D 3  in their basal diet. Vitamin D 3  aids normal calcium transport and metabolism. Vitamin D 3  is also somewhat effective in preventing the development of tibial dyschondroplasia. As seen in Tables 3 and 4, however, chickens given a basal diet which includes 1100 ICU of vitamin D 3  still have a high incidence of tibial dyschondroplasia (Study 1, 42% incidence; Study 2, 39%; Study 3, 18%; Study 4, 35%). Administration of additional vitamin D 3  to the chickens&#39; diet in some cases slightly reduces the incidence of the disease (Study 1, 26% incidence; Study 2, 31%), and in some cases does not effect the incidence of the disease at all (Study 3, 22% incidence; Study 4, 35%). However, administration of 10 μg of the vitamin D 3  derivative per day to chickens which are supplied vitamin D 3  in their basal diet produces a significant decrease in the incidence of the disease (Study 3, 9-12% incidence; Study 4, 8-16% incidence). 
     The amount of vitamin D 3  found effective to cause a reduction in the incidence of tibial dyschondroplasia is in the range of 0.5 to 2 μg per kilogram of body weight of animal per day. 
     Poultry fed a basal diet which contains dietary vitamin D 3  and an effective amount of a vitamin D 3  derivative will have a lower incidence of tibial dyschondroplasia than those fed an effective amount of the vitamin D 3  derivative alone, as seen in Table 1. 
     
                                           TABLE 1                                 
__________________________________________________________________________
D.sub.3     16-d   Bone                                                   
                      Ricket                                              
                           Tibial dyschondroplasia                        
ICU/kg                                                                    
     1,25(OH).sub.2 D.sub.3                                               
            wt Gain/                                                      
                   ash                                                    
                      incidence                                           
                           Incidence                                      
diet μg/kg diet                                                        
            g  feed                                                       
                   %  %    %    Score                                     
                                    % #3                                  
                                        #3/total                          
__________________________________________________________________________
  0  0      345                                                           
               .667                                                       
                   34.3                                                   
                      37   87   1.4 17  5/30                              
  0  .1     343                                                           
               .652                                                       
                   34.0                                                   
                      70   76   1.3 11  3/29                              
  0  1      344                                                           
               .641                                                       
                   35.3                                                   
                      33   78   1.2 12  3/28                              
  0  10     350                                                           
               .621                                                       
                   38.7                                                   
                       0    0   0.sup.e                                   
                                    0   0/29                              
1100 0      329                                                           
               .626                                                       
                   35.7                                                   
                      24   59   0.9 7   2/29                              
1100 .1     349                                                           
               .630                                                       
                   36.3                                                   
                      27   63   1.0 7   2/30                              
1100 1      356                                                           
               .685                                                       
                   36.3                                                   
                       7   37   0.5 3   1/30                              
1100 10     348                                                           
               .609                                                       
                   39.0                                                   
                       0   18   0.2 0   0/28                              
__________________________________________________________________________
 
    
     It is clear that the vitamin D 3  derivatives are not mere substitutes for vitamin D 3 , but are performing a biological role separate from and in addition to that of vitamin D 3 . 
     Administration of Combinations of Vitamin D 3  Derivatives 
     Another embodiment of the present invention includes administering the vitamin D 3  derivatives in combination, with or without Vitamin D 3 . For example, a composition delivering a dosage of a 0.1-20 g of a combination of the vitamin D 3  derivatives per day to poultry is efficacious in treating and preventing tibial dyschondroplasia. Any of the compounds of the present invention may be administered in such composition combinations. 
     Preparation of Compositions to Treat Tibial Dyschondroplasia 
     The compositions of the present invention may be administered to the animals orally, subcutaneously, intramuscularly, intravenously or intraperitoneally. For example, it may be given in a feed composition, the water supply, by injection, or by a controlled drug delivery device such as a time or slow release bolus, a microsphere, a microcapsule, or an orally administered capsule which can be time released. 
     Biodegradable, biocompatible implants are presently in use for controlled drug delivery in humans and animals. Acceptable materials for the delivery matrix include cellulose, gelatin, polylactides, polyglycolides, polyanhydrides, polyorthoesters, polyethylene vinyl acetate, and other polymers which degrade hydrolytically or enzymatically once implanted. The vitamin D 3  derivatives of the present invention can be incorporated into microspheres or microcapsules of these materials or other materials known to those of skill in the art. The microspheres or microcapsules are then implanted into the animal for release of the drug over time. 
     Suitable pharmaceutically acceptable carriers for veterinary drug delivery are known to those of skill in the art, and include saline, PBS (phosphate-buffered saline) and propylene glycol. 
     In the preferred dietary composition for the treatment of tibial dyschondroplasia in fowl, an effective amount of 1,25-dihydroxycholecalciferol (1), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (2), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24-fluorocholecalciferol (6) or 25-hydroxycholecalciferol (7, or a combination thereof, is provided in combination with sources of energy such as corn, fat and soybean meal; sources of protein such as corn and soybean meal; amino acids such as DL-methionine; mineral sources such as iodized sodium chloride, a trace mineral mixture, selenium concentrate (0.02% sodium selenite), a phosphorus source such as dicalcium phosphate, a calcium source such as dicalcium phosphate and limestone and a vitamin mixture. 
     The vitamin mixture provides in milligrams/kilogram of diet (except as noted) vitamin A (as all-trans-retinyl acetate), 5,500 IU; vitamin D 3  (cholecalciferol), 1100 ICU or 27.5 μg; vitamin E (all-rac-α-tocopheryl acetate), 11 IU; riboflavin, 4.4; calcium pantothenate, 12; nicotinic acid, 44; choline Cl, 220; vitamin B 12 , 9; vitamin B 6 , 3.0; menadione (as menadione sodium bisulfite), 1.1; thiamin (as thiamin mononitrate) 2.2; folic acid, 3; biotin, 0.3; and ethoxyquin, 125. 
     The trace mineral mixture provides in milligrams/kilogram of diet MnO 2 , 222; ZnO, 150, FeSO 4  ·H 2  O, 200; FeCO 3 , 83; C 2  SO 4 , 29; and Ca(IO 3 ) 2 , 15. 
     A supplemented chicken feed, to which the compounds of the present invention may be added in above described dosages, is given in Table 2. 
     
                       TABLE 2                                                     
______________________________________                                    
Composition of the basal diet.                                            
                       Amounts                                            
Ingredients            %                                                  
______________________________________                                    
Ground yellow corn     56.81                                              
Soybean meal (dehulled)                                                   
                       35.00                                              
Poultry fat (stabilized)                                                  
                       5.00                                               
Iodized sodium chloride                                                   
                       0.45                                               
D,L-Methionine (98%)   0.20                                               
Vitamin premix (as described above)                                       
                       0.25                                               
Trace mineral premix (as described                                        
                       0.10                                               
above)                                                                    
Se concentrate (0.02% from sodium                                         
                       0.05                                               
selenite)                                                                 
Dicalcium phosphate (feed grade)                                          
                       1.86                                               
Limestone              0.28                                               
______________________________________                                    
 
    
     The active compounds of the present invention can also be administered in combination with other commercially formulated or similar feeds. 
     Chickens fed the diet described in Table 2, without the vitamin D 3  derivatives of the present invention, will have a higher than normal incidence of tibial dyschondroplasia even though the diet contains a high level of vitamin D 3 , because the diet has a high level of chloride and phosphorus and a low level of calcium (average analyzed values Cl 0.32%, P 0.76%, Ca 0.75%). 
     The compounds of the present invention are efficacious in a feed having any calcium composition, particularly those with a calcium composition of less than  2 .5 % by weight. Broiler chickens are typically fed a diet which has a range of calcium of 0.7 to 1.4% by weight, while egg laying hens are fed a diet with a higher calcium level. 
     A control system to test the effect of the vitamin D 3  derivatives on the incidence of tibial dyschondroplasia in fowl was developed using disulfiram [bis(diethylthiocarbamyl)disulfide], an alcohol deterrent, in a dietary dosage of approximately 30 mg/kg feed per day. Disulfiram supplementation lowers the absorption of calcium when given as an oral dose compared to controls. It is known that thiruram [bis(dimethylthiocarbamyl)disulfide], a compound used as a fungicide and bactericide which is structurally close to disulfiram and which also causes tibial dyschondroplasia, causes a rapid loss of intramuscularly injected calcium immediately after dosing. This suggests that calcium in the blood and soft tissues (gastrointestinal tract) can be lost more easily from the birds receiving thiruram or disulfiram but that once the calcium goes into the bone both thiruram and disulfiram have little effect on turnover. 
     Example of Treatment of Tibial Dyschondroplasia with Vitamin D 3  Derivatives 
     The effectiveness of 1,25-dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), and 1,25-dihydroxy-24-fluorocholecalciferol (6) in reducing the incidence of tibial dyschondroplasia in chickens has been demonstrated using the following experimental procedure. 
     Newly hatched Peterson X Arbor Acre cockerels obtained from a commercial hatchery were used. The chickens were kept in electrically heated Petersime battery brooders with wire mesh floors located in a room in which the temperature was maintained at 22° C.; fluorescent lights were on 24 hours each day in the room and the cages, and sunlight was present during the day from large windows. There was no attempt to limit the natural production of Vitamin D 3 . Ten birds were placed in each section of the Petersime batteries used at the start of the experiment. Food and water were always available to the chickens. The basal diet used is as described in Table 2. Disulfiram was added to the basal diet of some chickens as indicated in Table 4 at a level of 30 milligrams/kilogram of feed. Vitamin D 3  and its metabolites were added as indicated in Tables 3 and 4 to the diet at the following levels: Vitamin D 3 , 27.5 micrograms per kilogram of feed (1100 ICU/kilogram); 1,25-dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24(R),25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24(R)-fluorocholecalciferol (6), and 25-hydroxycholecalciferol (7) at 10 g/kg. 
     
                                           TABLE 3                                 
__________________________________________________________________________
Study 1                                                                   
              16 Day     Bone  Tibial Dyschondroplasia                    
              wts.       ash   Incidence                                  
Treatments    g.    G:F  %     %     Score #3/total                       
__________________________________________________________________________
Basal         416   .696 40.6  42    2.77  10/30                          
Basal + D.sub.3                                                           
              451   .734 40.4  26    2.38  4/27                           
Basal + 25OHD.sub.3                                                       
              395   .667 40.2  17    1.50  1/28                           
Basal + 1,25(OH).sub.2 D.sub.3                                            
              421   .670 42.5  13    1.75  1/29                           
Disulfiram    433   .750 39.9  70    2.71  16/30                          
Disulfiram + D.sub.3                                                      
              432   .708 40.0  40    2.80  9/27                           
Disulfiram + 25OHD.sub.3                                                  
              398   .706 39.7  58    2.54  11/30                          
Disulfiram + 1,25(OH).sub.2 D.sub.3                                       
              426   .701 41.9  23    2.33  4/30                           
Means ± SEM                                                            
              420 ± 13                                                 
                    .704.032                                              
                         40.6 ± .2                                     
                               36 ± 9                                  
                                     2.11 ± .48                        
__________________________________________________________________________
Study 2                                                                   
             16 Day  Bone                                                 
                         Tibial Dyschondroplasia                          
             wts.    ash Incidence     .sup.47 Ca                         
Treatments   g   G:F %   %    Score                                       
                                  #3/total                                
                                        Intercept                         
                                            Slope                         
__________________________________________________________________________
Basal        375 .707                                                     
                     40.5                                                 
                         39   1.94                                        
                                  6/29 72   -1.60                         
Basal + D.sub.3                                                           
             368 .647                                                     
                     40.5                                                 
                         31   2.47                                        
                                  5/29 77   -1.88                         
Basal + 25OHD.sub.3                                                       
             392 .713                                                     
                     40.6                                                 
                         27   2.78                                        
                                  7/30 72   -1.59                         
Basal + 1,25(OH).sub.2 D.sub.3                                            
             361 .661                                                     
                     42.2                                                 
                         13   2.17                                        
                                  2/30 84   -2.85                         
Disulfiram   394 .671                                                     
                     40.3                                                 
                         65   2.76                                        
                                  14/28                                   
                                       73   -1.59                         
Disulfiram + D.sub.3                                                      
             374 .666                                                     
                     40.3                                                 
                         51   2.74                                        
                                  12/30                                   
                                       72   -1.97                         
Disulfiram + 25OHD.sub.3                                                  
             395 .728                                                     
                     40.5                                                 
                         49   2.76                                        
                                  11/28                                   
                                       74   -1.67                         
Disulfiram + 1,25(OH).sub.2 D.sub.3                                       
             377 .684                                                     
                     42.0                                                 
                         30   2.44                                        
                                  6/30 79   -2.11                         
Means ± SEM                                                            
             380 ±                                                     
                 .685 ±                                                
                     40.8 ±                                            
                         38 ±                                          
                              2.51 ±                                   
                                       75 ±                            
                                            -1.91 ±                    
              12 .026                                                     
                      .3  9    .31      3     .29                         
__________________________________________________________________________
 
    
     
                                           TABLE 4                                 
__________________________________________________________________________
Study 3                                                                   
Vit. D   16 Day                                                           
              Gain/ Bone     Tibial Dyschondroplasia                      
                                                    Ca.sup.47             
Compound Wt.  Feed  Ash Incidence                                         
                             Score #3/No.                                 
                                        % N3  % N2 + 3                    
                                                    Ret.                  
                                                        Slope             
__________________________________________________________________________
none     421  .711.sup.a                                                  
                    63       1.85  11/60                                  
                                        18    37    70.sup.bc             
                                                        -1.01.sup.b       
D.sub.3  434  .709.sup.a                                                  
                    82       1.69  13/59                                  
                                        22    34    75.sup.abc            
                                                        -1.13.sup.b       
1,25(OH).sub.2 D.sub.3                                                    
         421  .666.sup.b                                                  
                    56       1.48  5/58 9     16    78.sup.ab             
                                                        -.72.sup.ab       
24,25(OH).sub.2 D.sub.3                                                   
         424   .696.sup.ab                                                
                    78       2.03  17/59                                  
                                        29    53    67.sup.c              
                                                        -.77.sup.ab       
1,24,25(OH).sub.2 D.sub.3                                                 
         428   .688.sup.ab                                                
                    57       1.58  6/60 10    22    76.sup.abc            
                                                        -.77.sup.ab       
1OHD.sub.3                                                                
         423  .661.sup.b                                                  
                    42       1.51  3/60 5     17    75.sup.abc            
                                                        -.95.sup.b        
1,25(OH).sub.2 -26-                                                       
         422   .687.sup.ab                                                
                    42       1.30  0/60 0      8    80.sup.a              
                                                         .15.sup.a        
27[.sup.2 H].sub.6 D.sub.3                                                
1,25(OH).sub.2 -                                                          
         413  .663.sup.b                                                  
                    60       1.36  3/60 5     15    72.sup.abc            
                                                        -.47.sup.ab       
24R-FD.sub.3                                                              
Mean ± SEM                                                             
         423 ± 7                                                       
              .685 ± .013                                              
                    59 ± 7                                             
                             1.60 ± 15                                 
                                        12 ± 4.5 74 ± 3             
                                                        -.71 ± .31     
Analysis of                                                               
         .555 .044  &lt;.001    .019       &lt;.001       .064                  
                                                         .118             
variance                                                                  
probabilities:                                                            
Treatment                                                                 
__________________________________________________________________________
Study 4                                                                   
              Vitamin D    16 Day                                         
                                Gain/ Bone  Tibial dyschondroplasia       
              compound     wt.  feed  ash   Incidence Score               
                                                      %                   
                                                          #3/total        
__________________________________________________________________________
              None (basal diet)                                           
                           356.sup.cdl                                    
                                .681.sup.ab                               
                                      35.07.sup.c                         
                                            54.sup.a                      
                                                2.30.sup.ab               
                                                      35.sup.a            
                                                          19/55           
              D.sub.3      383.sup.a                                      
                                .701.sup.a                                
                                      35.68.sup.bc                        
                                            44.sup.ab                     
                                                2.75.sup.a                
                                                      35.sup.a            
                                                          20/58           
              1,25(OH).sub.2 D.sub.3                                      
                           355.sup.cd                                     
                                .652.sup.b                                
                                      36.88.sup.a                         
                                            18.sup.d                      
                                                1.58.sup.b                
                                                       8.sup.b            
                                                           4/52           
              24,25(OH).sub.2 D.sub.3                                     
                           351.sup.d                                      
                                .663.sup.b                                
                                      35.53.sup.bc                        
                                            53.sup.a                      
                                                2.78.sup.a                
                                                      46.sup.a            
                                                          25/56           
              1,24,25(OH).sub.2 D.sub.3                                   
                           376.sup.ab                                     
                                .681.sup.ab                               
                                      36.07.sup.b                         
                                            23.sup.cd                     
                                                1.89.sup.ab               
                                                      14.sup.b            
                                                           8/57           
              1OHD.sub.3   372.sup.abc                                    
                                .655.sup.b                                
                                      36.77.sup.a                         
                                            29.sup.bcd                    
                                                2.21.sup.ab               
                                                      15.sup.b            
                                                           8/57           
              1,25(OH).sub.2 -26-27[.sup.2 H].sub.6 D.sub.3               
                           360.sup.bcd                                    
                                .646.sup.b                                
                                      37.45.sup.a                         
                                            16.sup.d                      
                                                1.63.sup.b                
                                                       7.sup.b            
                                                           4/58           
              1,25(OH).sub.2 -24R-FD.sub.3                                
                           360.sup.bcd                                    
                                .661.sup.b                                
                                      35.48.sup.bc                        
                                            41.sup.abc                    
                                                2.06.sup.ab               
                                                      16.sup.b            
                                                           9/56           
              Mean ± SEM                                               
                           364 ± 6                                     
                                .667 ± .012                            
                                      36.12 ± .23                      
                                            34 ± 6                     
                                                2.15 ± .31             
                                                      22 ± 5           
              Analysis of variance                                        
                           .0059                                          
                                .0273 .0001 .0001                         
                                                .0605 .0001               
              probabilities:                                              
              Treatment                                                   
__________________________________________________________________________
 .sup.1 Duncan&#39;s multiple range test, values with different superscript   
 letters are significantly different, P ≦ 0.05.                    
 
    
     At 16 days of age, pen body weights were obtained for all birds and their feed consumption was recorded. The birds were then killed and all birds were examined at random for tibial dyschondroplasia by making a longitudinal cut across the tibia and scoring for incidence and severity of tibial dyschondroplasia. 
     The method used to score the severity of the disease is described in H. Edwards and J. Veltmann, &#34;The Role of Calcium and Phosphorus in the Etiology of Tibial Dyschondroplasia in Young Chicks&#34;, J. Nutr., 113, 1568 (1983), incorporated herein by reference. Briefly, using a three week old chicken as the reference animal, a score of zero indicates normal cartilage which is narrow with little irregularities. A score of one indicates cartilage which is thickened or shows considerable irregularities. A score of two indicates that the cartilage is thickened and there is evidence of persisting prehypertrophic cartilage that is not calcified and which has not been invaded by vessels from the metaphysis. Deep irregularities are apparent. A score of three indicates a large mass of cartilage in the proximal end of the tibia. 
     After the tibia was scored for incidence and severity of tibial dyschondroplasia, the left tibia was removed for a bone ash determination on the fat-free dried bone. 
     Absorption and retention of dietary calcium was measured by orally dosing chicks with  47  Ca and then measuring the total body radioactive count, as described in Suso and Edwards, &#34;A Study of Techniques for Measuring  65  Zn Absorption and Biological Half-life in the Chicken,&#34; Poult. Sci. 47:991-999 (1968). Specifically, ten 7 day old birds in one pen under the indicated dietary treatments were dosed orally with 0.5 milliliter of water solution containing 0.5 microcuries of  47  Ca and 0.1-1.0 micrograms of calcium. The total body radioactive content of the individual chickens was determined immediately following dosing, and also on day 7, 9, 12 and 14 following dosing. A plot of percent administered  47  Ca which was retained versus number of days retained yields a line which has a slope corresponding to the half-life of the radioactive calcium in the chicken, and a y-intercept that corresponds to the amount of calcium absorbed by the chicken. 
     Effect of 1,25-Dihydroxycholecalciferol, 1,25-Dihydroxy-26,27-hexadeuterocholecalciferol, 1-Hydroxycholecalciferol, 1,24,25-Trihydroxycholecalciferol, 1,25-Dihydroxy-24-fluorocholecalciferol, and 24,25-(OH)2-Dihydroxycholecalciferol. 
     In Studies 1 and 2, the effect in broiler cockerels of Vitamin D 3 , 25-hydroxycholecalciferol, and 1,25-dihydroxycholecalciferol on growth, feed efficiency, bone ash,  47  Ca retention, and incidence and severity of tibial dyschondroplasia was determined. The results are shown in Table 3. The basal diet contained 1100 ICU (27.5g) vitamin D 3  /kg feed. Disulfiram was added as indicated to the diets of some chickens to increase the incidence of the disease, in order to further measure the effectiveness of the compounds. 
     As seen in Table 3, 1,25-dihydroxycholecalciferol, in the presence or absence of disulfiram, reduced the incidence and severity of tibial dyschondroplasia over the basal diet, and increased bone ash. 25(OH)-Cholecalciferol, in the presence or absence of disulfiram, also reduced the incidence of tibial dyschondroplasia over the basal diet. Further, a diet with 1,25-(OH)2-dihydroxycholecalciferol resulted in significantly more dietary  47  Ca absorbed than in a basal diet, while increasing the half life, or retention, of the calcium administered. 
     Table 4 illustrates the results of Studies 3 and 4, in which the effect of vitamin D 3  (cholecalciferol) (1), 1,25- dihydroxycholecalciferol (2), 1,25-dihydroxy-26,27-hexadeuterocholecalciferol (3), 1-hydroxycholecalciferol (4), 1,24,25-trihydroxycholecalciferol (5), 1,25-dihydroxy-24-fluorocholecalciferol (6), and 24,25-(OH)2-dihydroxycholecalciferol, on the incidence and severity of tibial dyschondroplasia, bone ash and absorption and retention of calcium was measured. The basal diet contained 1100 ICU of Vitamin D 3  per kg feed. 
     Studies 3 and 4 substantiated the results of studies 1 and 2 that administration of 10 μg/kg feed of 1,25-dihydroxycholecalciferol to the bird per day for the life of the bird substantially reduces the incidence and severity of tibial dyschondroplasia over the basal diet, and increases bone ash. 
     The addition of 24,25-dihydroxycholecalciferol was not effective in preventing the development of tibial dyschondroplasia. 
     The chickens that received feed containing 1,24,25-trihydroxycholecalciferol, 1-hydroxycholecalciferol, 1,25-dihydroxy-26,27-hexadeuterocholecalciferol and 1,25-dihydroxy-24-fluorocholecalciferol had a significant reduction in the incidence of tibial dyschondroplasia. 
     Preparation of Vitamin D 3  Derivatives 
     The vitamin D 3  derivatives of the present invention can be prepared by the following procedures. 
     1,25-Dihydroxycholecalciferol can be prepared as described in Biochemistry 10(14), 2799 (1971), and U.S. Pat. No(s). 4,310,467 and 3,697,559. 
     1,25-Dihydroxy-26,27-hexadeuterocholecalciferol can be prepared as described for the synthesis of 1,25-dihydroxycholecalciferol in Tet. Let. 40, 4147 (1972), with the substitution of a trideuteromethyl Grignard reagent in place of the methyl Grignard reagent used to add the carbons at the 26 and 27 positions. 
     1-Hydroxycholecalciferol can be prepared by the methods described in J. Am. Chem. Soc. 95(8), 2748 (1973) and U.S. Pat. No. 3,741,996. 
     1,24,25-Trihydroxycholecalciferol can be prepared by the method described in U.S. Pat. No. 3,847,955. 
     1,25-Dihydroxy-24-fluorocholecalciferol can be prepared by the procedure described in J. Oro. Chem. 53(5), 1040 (1988). 
     25-Hydroxycholecalciferol can be prepared as described in U.S. Pat. No(s). 4,310,467 and 3,565,924. 
     Modifications and variations of the present invention of a method and compositions to treat tibial dyschondroplasia will be obvious to those of skill in the art from the foregoing detailed description of the invention. Such modifications and variations are intended to come within the scope of the appended claims.