Background and friimma-ry of the Invention

Up to 80% of the phosphorus (P) present in plant foods and feeds exists as a complex of phytic acid (myoinositol hexaphosphate), hereinafter referred to as phytate. Phytate may structurally be illustrated by the following formula:

The P in phytate cannot be totally digested by simple-stomached animals, including humans, and it therefore passes through the gastrointestinal (GI) tract and is excreted in the feces. In animal nutrition, this is accounted for in diet formulation whereby 1.5 to 2.0% of an inorganic phosphate source is supplemented to meet the animal's minimal P requirement. Addition of inorganic P to poultry, swine, companion animal, and fish diets is expensive. It is often stated that supplemental P for these species is the third most expensive dietary ingredient, after energy and protein. The body requires P for formation of bones and teeth, for phospholipid (cell membrane structure) and nucleic acid (RNA, DNA) synthesis, for synthesis of ATP and other high-energy P compounds, and for proper acid-base balance in the body. Roughly 85% of the body P is in the

skeleton. Bone is comprised of 50% organic matrix (protein in the form of collagen, and lipid) and 50% inorganic material (mostly a Ca-P salt, i.e., hydroxyapatite).

Supplemental inorganic P is provided to animal diets in one of three feedgrade forms; dicalcium phosphate (18.5% P), monocalcium phosphate (21.5% P) or deflorinated phosphate (18.0% P). The combined total market for these products is estimated to be 675 million dollars per year in the U.S., Canada, Mexico, Western Europe and Japan. If one were to include South America, Eastern Europe, Asia, Africa, China, India, and Southeast Asia, (where market data are difficult to obtain), the total market for feed-grade phosphates could easily be expected to exceed 1 billion dollars annually. In North America, 50% of feed-grade phosphate consumed is used for poultry feeding. It has been discovered that use of a bioactive 1 -α-OH vitamin D compound would reduce the need for supplemental P by up to 40%, and if combined with the enzyme phytase, could reduce the need by up to 50% to 60%.

Phytate complexes in plant foods and feeds (eg., cereal grains and by-products, beans) also bind cations such as calcium, potassium, magnesium, zinc, iron and manganese (Erdman, 1979) illustrated schematically as follows:

A bioactive feed additive that causes the utilization of P from phytate should also increase utilization of these elements as well. The present invention has established that 1-α-OH vitamin D compounds, preferably 1 ,25 dihydroxycholecalciferol and 1-α- OH cholecalciferol, increase the utilization of not only P but also zinc, iron and manganese. Thus, because these three trace elements are always added in supplemental form to diets for swine, poultry and companion animals (as feed-grade ZnO or ZnS0 ₄ *H ₂ 0; FeS0 ₄ ^» H ₂ 0; MnO or MnSO ₄ »H ₂ 0) use of a bioactive 1- α-OH vitamin D compound would lower, or perhaps eliminate, the need for supplemental quantities of these mineral salts in a practical-type grain-oilseed meal diet.

By replacing up to 0.75% of the diet as a P supplement and up to 0.10% as trace mineral salts, the remaining diet would contain more usable energy. Thus, grain-oilseed meal diets generally contain about 3,200 kcal metabolizable energy per kilogram of diet, and mineral salts supply no metabolizable energy. Removal of the unneeded minerals and substitution with grain would therefore increase the usable energy in the diet. Currently, phytase is being used in much of Europe and

Asia to reduce P pollution. The use level, however, is 600 units per kilogram diet, but this level was selected because of cost of the enzyme and not because 600 units will maximize phytate utilization. In contrast it has been discovered via the present investigation that at least 1200 units/kg diet is required to maximize phytate utilization in chicks fed a corn- soybean meal diet (Table 1). However, use of a bioactive 1-α-OH vitamin D compound in accordance with the present invention would reduce the need to feed expensive levels of phytase. (Table 5) Animal producers are forced to feed high P diets because of the phytate content of diets. This increases P in the excreta waste products (both feces and urine). Excess P from animal, as well as human waste, is generally spread on the soil, where a

portion of it gets washed into ground water and then into ponds, streams, rivers, lakes and oceans. Too much P in water stimulates growth of algae, and algae take up considerable oxygen. This robs marine life of the oxygen they need to grow, reproduce and thrive.

In many parts of Europe and Asia, P pollution has become such a problem and concern that penalties in the form of stiff financial fines are imposed on livestock producers who spread too much P-laden manure on the soils. Because of this, much of Europe now uses a microbial phytase product (BASF), even though this product (which also hydrolyzes phytate) is very expensive, in fact too expensive to be cost effective (at 600 units/kg diet) as a feed additive in the U.S. at the present time. Many U.S. soils are being described as "P saturated", thus resulting in a greater concentration of P in soil leachates. High-

P water leachate in areas such as the Chesapeak Bay has been blamed for excessive algae growth and increased fish kills in bay waters (Ward, 1993). In Europe, the feed industry group FEFANA issued a position paper in 1991 entitled "Improvement of the Environment". They proposed that P in manure from livestock production should be reduced by 30% (Ward, 1993). The limits of P that can be applied to soils in Europe have been discussed by Schwarz ( 1994). Accordingly, it is estimated that use of a 1-α-OH vitamin D compound that is active in increasing phosphorus utilization in accordance with the present invention, could cut the P content of animal waste products by up to 40%.

Initial work focused on use of 1 ,25 dihydroxycholecalciferol ( l ,25-(OH) ₂ D ₃ ) in the absence or presence of 1200 units of microbial phytase (BASF), Edwards ( 1993) showed that l ,25-(OH) ₂ D ₃ is effective in improving P utilization from phytate- bound P. and Biehl et al ( 1995) confirmed his results. Moreover, both studies showed that l ,25-(OH) ₂ D ₃ works additively with

microbial phytase in releasing P from dietary phytate complexes. It seems likely that l ,25-(OH) ₂ D ₃ exerts is effects in two ways: (a) the 1 ,25 compound likely increases the activity of intestinal phytases or phosphatases that hydrolyze phytate (Pileggi et al, 1955; Maddaiah et al, 1964) and (b) the 1 ,25 compound is known to stimulate phosphate transport (Tanka and DeLuca, 1974), facilitating transport of P from GI tract to plasma and hence bone.

Under normal dietary circumstances, cholecalciferol (vitamin D ₃ ) that is added to a diet gets absorbed from the GI tract and is transported via blood to the liver where the liver enzyme 25-hydroxylase acts on the compound to cause formation of 25-OH D ₃ . This compound is the normal blood metabolite of cholecalciferol. A small portion of 25-OH D ₃ undergoes a further hydroxylation step in the kidney, at the 1-α position, causing synthesis of the calciotropic hormone l ,25-(OH) ₂ D ₃ . Because l ,25-(OH) ₂ D ₃ is expensive to synthesize and because oral 25-OH D ₃ is not the active form in phosphate absorption, it was proposed that l-oc-OH D ₃ would be an effective compound for increasing phosphate utilization. It has been discovered that lα- hydroxylated vitamin D compounds and particularly 1 -α-OH D ₃ will be absorbed from the GI tract and then be transported to the liver where 25-hydroxylase would act upon it to bring about synthesis of 1 ,25-dihydroxylated compounds and particularly l ,25-(OH) ₂ D ₃ . A portion of these compounds would then be transported back to the GI tract where they would activate intestinal phosphate absorption. The net effect would be an increased utilization of P (also Zn, Fe, Mn and Ca) from the phytate complex. In summary, the potential benefits of the present invention include ( 1) reduction in the need for inorganic P supplements for animal (including fish) diets; (2) reduction in P pollution of the environment; (3) reduction or possible

elimination of the need for supplemental Zn, Mn and Fe in animal diets; and (4) reduction of the quantity of phytase needed for maximal P utilization from feeds.

Detailed Description of the Preferred Embodiment As used in the description and in the claims, the term hydroxy-protecting group signifies any group commonly used for the temporary protection of hydroxy functions, such as for example, alkoxycarbonyl, acyl, alkylsilyl, and alkoxyalkyl groups, and a protected hydroxy group is a hydroxy function derivatized by such a protecting group. Alkoxycarbonyl protecting groups are groupings such as methoxycarbonyl, ethoxycarbonyl, propoxy carbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, tert-butoxycarbonyl, benzyloxycarbonyl or allyloxycarbonyl. The term "acyl" signifies an alkanoyl group of 1 to 6 carbons, in all of its isomeric forms, or a carboxyalkanoyl group of 1 to 6 carbons, such as an oxalyl, amlonyl, succinyl, glutaiyl group, or an aromatic acyl group such as benzoyl, or a halo, nitro or alkyl substituted benzoyl group. The word "alkyl" as used in the description or the claims, denotes a straight-chain or branched alkyl radical of 1 to 10 carbons, in all its isomeric forms. Alkoxyalkyl protecting groups are groupings such as methoxymethyl, ethoxyethyl, methoxyethoxymethyl, or tetrahydrofuranyl and tetrahydropyranyl. Preferred alkylsilyl protecting groups are trimethylsilyl, triethylsilyl, t- butyldimethylsilyl, and analogous alkylated silyl radicals.

The vitamin D compounds useful in the present treatment are lα-hydroxylated vitamin D compounds, preferably l α-hydroxycholecalciferol and l α,25-dihydroxycholecalciferol. The vitamin D compounds of this type are characterized by the following general structure:

where Xi may be hydrogen or a hydroxy- protecting group, X ₂ may be hydroxy, or protected hydroxy, X ₃ may be hydrogen or methyl, X ₄ and X ₅ each represent hydrogen or taken together X ₄ and X _δ represent a methylene group, and where Z is selected from Y, -OY, -CH ₂ OY,-C≡CY and-CH=CHY, where the double bond may have the cis or trans stereochemical configuration, and where Y is selected from hydrogen, methyl, -CR ₅ O and a radical of the structure:

R ¹ R ² _R 3

— (CH ₂ ) _m — C — (CH ₂ )n - C — R ⁵

where m and n, independently, represent integers from 0 to 5, where R ¹ is selected from hydrogen, hydroxy, protected- hydroxy, fluoro, trifluoromethyl, and Cι - ₅ -alkyl, which may be straight chain or branched and, optionally, bear a hydroxy or protected-hydroxy substituent, and where each of R ² , R ³ and R ⁴ , independently, is selected from hydrogen, fluoro, trifluoromethyl and C ₁ - ₅ alkyl, which may be straight-chain or branched, and optionally bear a hydroxy or protected-hydroxy substituent, and where R ¹ and R ² , taken together, represent an

oxo group, or an alkylidene group, =CR ₂ R ₃ , or the group -(CH ₂ ) _P -, where p is an integer from 2 to 5, and where R3 and R4 , taken together, represent an oxo group, or the group -(CH ₂ ) _q -, where q is an integer from 2 to 5, and where R5 presents hydrogen, hydroxy, protected-hydroxy, or C ₁ - ₅ alkyl.

The above compounds may be administered alone or in combination with other feed additive agents. The above vitamin D compounds or combinations thereof can be readily administered either by mixing them directly into animal feed or separately from the feed by separate oral dosage, by injection or by transdermal means or in combination with other lα- hydroxylated vitamin D compounds, the proportions of each of the compounds in the combination being dependent upon the particular problem being addressed and the degree of response desired, are generally effective to practice the present invention.

In poultry, amounts in excess of about 10 micrograms per day or the combination of that compound with other 1 α-hydroxylated vitamin D compounds, are generally unnecessary to achieve the desired results, may result in hypercalcemia, and may not be an economically sound practice. It should be understood that the specific dosage administered in any given case will be adjusted in accordance with the specific compounds being administered, the problem to be treated, the condition of the subject and the other relevant facts that may modify the activity of the compound or the response of the subject, as is well known by those skilled in the art. In general, either a single daily dose or divided daily dosages may be employed, as is well known in the art.

If administered separately from the animal feed, dosage forms of the various compounds can be prepared by combining them with non-toxic pharmaceutically acceptable carriers to make either immediate release or slow release formulations, as is well known in the art. Such carriers may be either solid or liquid such as, for example, com starch, lactose, sucrose, peanut

oil, olive oil, sesame oil and propylene glycol. If a solid carrier is used the dosage form of the compounds may be tablets, capsules, powders, troches or lozenges or top dressing as micro- dispersable forms. If a liquid carrier is used, soft gelatin capsules, or syrup or liquid suspensions, emulsions or solutions may be the dosage form. The dosage forms may also contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents, solution promoters, etc. They may also contain other therapeutically valuable substances. The present invention also relates to an animal feed composition and method of compounding an animal feed utilizing a 1 α-hydroxylated vitamin D compound to lower the dietary requirement of phosphorus in the animal feed. The lα- hydroxylated vitamin D compounds suitable for this use have been previously described herein. The amount of a phosphorus supplement (18.5%P) that may be incorporated with the feed may be reduced to about 0.9% from about 1.9% on a dry weight basis. This is a significant reduction from the normal amount of phosphorus supplement incorporated in animal feed compositions of about 1.5% to about 2.5%. This beneficial reduction in phosphorus is a direct result of the incorporation of a 1 α-hydroxylated vitamin D compound in the animal feed.

The animal feed may be any protein-containing organic meal normally employed to meet the dietary requirements of animals. Many of such protein-containing meals are typically primarily composed of corn, soybean meal or a com/soybean meal mix. For example, typical commercially available products fed to fowl include Egg Maker Complete, a poultry feed product of Land O' Lakes AG Services, as well as Country Game & Turkey Grower a product of Agwa, Inc. Both of these commercially available products are typical examples of animal feeds with which the present 1 α-hydroxylated vitamin D compounds may be incorporated to reduce the amount of supplemental phosphorus.

zinc, manganese and iron intake required in such compositions. Thus, any type of protein-containing organic meal may be utilized as the base mix to which the 1 α-hydroxylated vitamin D compounds and reduced supplemental phosphorus, zinc, manganese and iron amounts of the present invention may be incorporated.

The present invention is applicable to the diet of numerous animals, which herein is defined as including mammals, fowl and fish. In particular, the diet may be employed with commercially significant mammals such as pigs, cattle, sheep, goats, laboratory rodents (rats, mice, hamsters and gerbils), fur-bearing animals such as mink and fox, and zoo animals such as monkeys and apes, as well as domestic mammals such as cats and dogs. Typical commercially significant fowl include chickens, turkeys, ducks, geese, pheasants and quail.

Commercially formed fish such as trout would also benefit from the diet disclosed herein.

In a method of compounding feed for animals in accordance with the present invention, the 1 α-hydroxylated vitamin D compounds utilized is incorporated with the animal feed in an amount of from about 5μg/kg to about 40μg/kg feed on a dry weight basis. The feed mixture is then fed as a mash or as formed into desired discrete shapes for further processing and packaging. In general, these discrete shapes may be pellets, blocks or briquettes formed by known extrusion and /or compacting techniques. The particular processing technique utilized does not affect the performance of the 1 α-hydroxylated vitamin D compounds in the animal feed mixture. The present invention is more specifically described by the following examples, which are meant to be illustrative only.

Chick Efficacy Trials A. Procedures:

The best measure of P (or Ca) activity in animals fed a P- deficient diet is total bone ash. In the present bioassay system, young chicks (8 d of age) are fed a corn-soybean meal diet containing 0.6% Ca and 0.43% total P. but an estimated 0.10% bioavailable P. The required levels of Ca and P for chicks of this age are 1.0% Ca and 0.45% available P (i.e., nonphytate P). Calcium is kept at 0.6% instead of 1.0% in our diet because excess Ca in the presence of a severe available P deficiency causes anorexia.

Generally speaking, three or four pens of three or four chicks per pen are placed on each dietary treatment. They are fed the experimental diets free choice for 12 d in wire-screened battery pens located in a environmentally controlled animal room with constant (fluorescent) lighting. At assay termination on d 20 post-hatching, chicks are killed by cervical dislocation and the left tibia is quantitatively removed. Bones are stripped of adhering tissue, dried for 24 h at 100°C, weighed and then dry ashed for 24 h at 600°C (muffle furnace). The portion remaining after ashing is entirely inorganic matter. The weight of ash (mineral matter) as a percent of dry bone weight is percent ash (mineral, and mostly Ca and P) in the bone. Percent ash multiplied by dry bone weight gives total bone ash in milligrams. Tibia ash reflects the degree of ash (or bone mineralization) in the entire skeleton. Our 20-d-old crossbred chicks (New Hampshire x Columbian) fed a diet adequate in Ca and P generally have percent bone ash values of 45%.

For assessment of Zn and Mn bioavailability, bone content of Zn and Mn are the established criteria, but growth responses are also used for assessment of Zn bioavailability (Wedekind et al, 1992; Halpin and Baker, 1986). For assessment of Zn or Mn bioavailability, the tibiae are dried at 100°C for 24 h, weighed,

and then dry ashed at 600°C for another 24 h. The dried ash is then wet ashed with HNO ₃ and H ₂ O ₂ . Zinc and manganese are then quantified using atomic absorption spectrophotometry (Wedekind et al, 1992). In research involving Zn, Mn or Fe (hemoglobin assay) bioavailability, the chicks are fed a pretest diet (0 to d-8 post-hatching) that is deficient in Zn, Mn or Fe. This depletes stores of these trace elements. The experiments are then carried out in stainless-steel chick batteries equipped with stainless-steel feeders and waterers. Deionized water is available free choice. These steps are taken to avoid Zn, Mn or

Fe contamination from the environment, equipment and drinking water. B. Results:

The basal diet for the first experiment was designed to be severely deficient in available P (most coming from phytate- bound P) but adequate to excess in vitamin D ₃ , and marginal in both Zn and Mn (i.e., no supplemental Zn or Mn in diet). Increases in bone ash would indicate enhanced GI absorption of P, and increases in bone Zn and Mn would indicate enhanced GI absorption of Zn and Mn (Chung and Baker, 1990; Wedekind et al, 1992; Halpin and Baker, 1986; Baker et al, 1986). As shown in Table 1 , growth rate was increased (P<0.05) 17% by 0. 10% P addition, 20% by 1200 U phytase addition, 15.5% by 1 ,25- (OH) ₂ D ₃ addition, and 25% by the combination of phytase ( 1200 U) and 10.0 μg/kg l ,25-(OH) ₂ D ₃ . Bone ash, however, is the best measure of P bioavailability. Total bone ash (mg) was increased (P<0.01) 56% by 0.10% P addition (proving that P was severely deficient in the diet), 64% with 1200 U phytase, 60% by 1.25- (OH) ₂ D ₃ , and 98% by the combination of phytase and 1 ,25- (OH) ₂ D ₃ . Tibia Zn (μg) was increased (P<0.01) 55% by either

1200 U phytase or 10 μg/kg l ,25-(OH) ₂ D . but was increased

86% by the phytase-di-OH D ₃ combination. Tibia Mn (μg) was increased (P<0.01) 63% by phytase, 85% by di-OH D ₃ and 123% by the phytase-di-OH D ₃ combination.

Data in Table 2 show results of a second efficacy trial. The basal diet for this trial was made adequate in Ca, and also was fortified with normal (safety factor) levels of Mn and Zn. It was thus singly deficient in available P. Bone ash was markedly depressed in chicks fed the P-deficient negative control diet. In fact, bone ash percent was about 5% lower (30.4% in Exp. 1 , 25.5% in Exp. 2) in these chicks, a reflection of the high ratio of

Ca to available P. Efficacy was again demonstrated for both phytase and l ,25-(OH) ₂ D ₃ . Moreover, the diet containing both phytase and l,25-(OH) ₂ D ₃ produced both ash values that were not far from those achieved with a P adequate diet (diet 5). Data in Table 3 show results of a classic Zn efficacy trial.

The basal diet was singly deficient in Zn (the NRC 1994 Zn requirement is 40 ppm) so that even with 10 ppm Zn addition, the diet was still Zn deficient. Marked efficacy was observed for both phytase and l,25-(OH) ₂ D ₃ , and additivity was again evident for the combination.

Having shown conclusively that l ,25-(OH) ₂ D ₃ is markedly efficacious in utilization of P, Zn and Mn, a trial was next conducted to test the efficacy of 1 -α-OH D ₃ . These results are shown in Table 4. A linear (P<0.01) growth response occurred when 1-α-OH D ₃ doses between 0 and 20 μg/kg were supplemented. Tibia ash likewise increased (P<0.01) markedly when 1-α-OH D ₃ was added to the diet. Total tibia ash (mg) was 69% higher in chicks fed the diet with 20 μg/kg 1 -α-OH D ₃ than in those fed the unsupplemented basal diet. A dose of 40 μg/kg 1 -α-OH D ₃ was efficacious, and certainly nontoxic, but the 20 μg/kg dose maximized the response attributable to P release from phytate.

Data in Table 5 verify the synergism between the combination of microbial phytase and l ,25-(OH) ₂ D ₃ . Also, the results demonstrate that when phytase (600 vs. 1200 units) doses are compared in the presence of 10 μg/kg l,25-(OH) ₂ D ₃ , 600 units of phytase are as effective as 1200 units in improving phytate-P utilization. This finding when compared to the data of Exp. 1 (Table 1) indicates that the phytase supplementation level required for maximum response can be cut in half if a supplemental bioactive 1-α-OH vitamin D compound is also included in the diet. In fact, only 300 units of phytase produced a marked response in the presence of l,25-(OH) ₂ D ₃ .

Data in Table 6 show that synergism exists between 1-α- OH D ₃ and phytase. Thus, 20 μg/kg 1-α-OH D ₃ combined with 1200 units of phytase increased total bone ash by 107% over that observed for the basal unsupplemented corn-soybean meal diet.

Supplemental 1-α-OH D ₃ alone increased bone ash by 74%, and supplemental phytase alone increased bone ash by 65%.

TABLE 1

Phytase and 1,25-Dihydroxycholecalciferol Increase Growth Rate and Bone

Strength of Young Chicks Fed a Phosphorus-Deficient Diet (Exp. 1)1

Weight Gain Avail. P Tibia data - gain feed intake Weight Ash Ash Zn Zn Mn Mn

Diet ^{2 (} g ⁾ (g/kg) (mg) (mg) (%) (mg) (μg/g) (μg) (μ/g) (μg)

Phosphorus titration ⁴

0 193 644 300 667 30.4 203

0.05% P 200 640 468 717 35.4 254 0. 10% P 226 657 688 827 38.3 317

Phytase titration υ 193 644 300 667 30.4 203 142 95 2.32 1.55 c

300 μ phytaseS 202 647 312 729 33.9 247 145 105 600 μ phytase 206 661 312 735 35.8 263 159 1 17 2.66 1 .96 900 μ phytase 224 664 338 805 38.2 308 171 137 1200 μ phytase 231 679 340 848 39.3 333 173 147 3.00 2.53

Factorial

1. 0 193 644 300 667 30.4 203 142 95 2.32 1.55

2. 1200 U phytases 231 679 340 848 39.3 333 173 147 3.00 2.53

3. 10 μg/kg DiOH D ₃ 6 223 683 326 816 39.6 324 179 147 3.52 2.87

4. As 2 + 3 241 707 340 932 43. 1 402 190 177 3.85 3.46

Pooled SEM 3.3 6.7 14 7.0 4.1 4.4 .10 .08

Table 1 footnotes on next page.

TABLE 1 FOOTNOTES

!Data represent means per chick of four replicate pens of four female chicks during the period 8 to 20-d posthatching; average initial weight was 82 g.

2The basal corn-soybean meal diet (23% CP) contained 0.10% available P and 0.60% Ca. Neither Mn or Zn were provided as supplements to this basal diet. The diet was adequate to excess in vitamin D ₃ , containing 1000 IU of supplemental cholecalciferol per kg of diet (25μg/kg).

3 Dry weight basis.

4Graded doses of P from KH ₂ P0 .

sphytase obtained from BASF Corp., Parsippany, NJ 07054. One unit (U) of phytase is defined as the quantity of enzyme required to liberate 1 μmol of inorganic P per minute from 1.5 mmol/L sodium phytase at pH 5.5 and 37°C. Phytase was added from a premix (Natuphos® 5.000 BASF) that contained 5,000 U of phytase activity per gram.

⁶ Dihydroxycholecalciferol (DiOH-D ₃ ) obtained from Hoffman- LaRoche, Inc., Nutley, NJ. DiOH-D was dissolved in propylene glycol to make a solution of lOμg/ml. The desired volume of DiOH-Dβ solution for each diet involved was then dissolved in petroleum ether, which was then premixed with basal diet and subsequently added to the completed diet for mixing.

TABLE 3 Efficacy of Phytase and 1,25 Di-OH-D ₃ in Chicks Fed a Zn-Deficient Diet (Exp. 3)ι

12 days Tibia Tibia

Diet2 gain (g) Zn (μg/g) Zn (μg)

1. Basal diet 169 44.7 34.2

2. As 1 + 1200 U phytase 209 62.2 54.9

3. As 1 + lOμg/kg Di-OH-D ₃ 201 60.3 53.1

4. As 2 + 3 241 88.4 88.7

5. As 1 + 5 ppm Zn (ZnS0 ₄ ^» 7H ₂ 0) 210 61.5 54.2

6. As 2 + 10 ppm Zn (ZnSO ^» 7H ₂ 0) 236 73.7 71.1 Pooled SEM 8 2.7

iData are means of four pens, each containing four male chicks weighing 84.5 g at day 8 posthatching; 12-d feeding period in stainless- steel batteries with chicks receiving deionized water. During the 8-d pretest period, chicks were fed a low Zn soybean meal diet.

² Soy concentrate-dextrose diet containing 13 ppm Zn.

TABLE 4

Dietary Addition of 1- -hydroxycholecalciferol Increases

Phytate-Phosphorus Utilization (Exp. 4)1

Dietary Level 12-d Gain Tibia Data-3. of l-α-OH-D ₃ weight gain feeds Weight Ash Ash (μg/kg) (g) (g/kg) (mg) (%) (mg)

0 228b 645b 724c 33.0b 238c

10 255a 676a 917b 38.9a 356b

20 266a 681a 992a 40.5a 402a

40 255a 677a 878b 41.1a 361b

Pooled SEM 3.6 6.5 21 .75 7.6

i Means of three pens of four chicks during the period 8 to 20 days posthatching.

² Added to a corn-soybean meal diet (23% CP) containing adequate vitamin D-3, 0.60% Ca and 0.43% P (0.10% estimated available P).

SMeans within columns with unlike superscript letters are significantly (P < 0.5) different.

TABLE 5

Performance and Bone Ash of Chicks Fed 1,25-Dihydroxycholecalciferol in the Absence or Presence of Three Levels of Microbial Phytase (Exp. 5)i

Weight Food Tibia data2

Dietary gains intake Weight Ash Ash addition ² (g) (g) (mg) (%) (mg)

1. None 203c 314c 672c 32.94 238d

2. lOμg/kg di-OH-D ₃ 234b 338b 825b 42.2c 348c

3. As 2 + 300 U phytase 244a 349a.b 881a.b 42.5b.c 375b

4. As 2 + 600 U phytase 251a 361a 903a 43.9a,b 396a.b

5. As 2 + 1200 U phytase 252a 356a 886a 44.7a 396a.b

Pooled SEM 3.6 4.6 20 0.5 9.0

iData are means for four pens of four female chicks that were fed the experimental diets during the period 8 to 20 d posthatching; average initial weight was 93 g. Means in columns with different superscripts letters are significantly different (P < 0.05).

² The basal diet (Table 1) contained, by analysis, 0.43% P (0.10% estimated available P), 0.63% Ca and 23% crude protein.

3Dry-weight basis.

TABLE 6

Evaluation of 1-α-Hydrox cholecalciferol With and

Without Phytase on Phosphorus Utilization!

Dietary Weight Food Tibia data addition gain intake Weight Ash Ash

g g mg g/ 100 g mg

1. None 195c 306b 634c 29. 1 c 185c

2. 0.10g P/ lOOg (KH ₂ P0 ₄ ) 223399a ^a ..bb 355a 801b 38.7b 310b

3. 1200 U phytase 245a.b 356a 795b 38.5b 306b

4. 20 μg/kg I-0.-OH-D ₃ 235b 343a 787b 40.9a 321b

5. As 3 + 4 253a 363a 897a 42.7a 384a Pooled SEM 5.5 6.6 18 0.7 11

iData are means of three pens of four female chicks that are fed the experimental diets during the period 8 to 20 d posthatching; average initial weight was 88 g. Means in columns with different superscript letters are significantly different (P < 0.05).

² The basal corn-soybean meal diet contained, by analysis, 0.43 g P/ 100 g (0.10 g/ 100 g estimated nonphytate P), 0.63 g Ca/ 100 g and 23.9 g CP/ lOO g.

³ Dry -weight basis.