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Effect of Chemical and Physical Properties of Phosphates on Energy Utilization by Chicks
GEESE CRAMMING AND ENZYMIC ACTIVITIES Effect of diet and digestive processes on proteolytic enzymes. J. Nutr. 83: 94-102. Weber, G., G. Banersee and S. B. Bronstein, 1962. Selective induction and suppression of liver enzyme synthesis. Am. J. Physiol. 202:137-144.
481
Westerfeld, W. W., D. A. Richert and A. C. Hermans, 1962. Growth and liver xanthine dehydrogenase in chicks and poults fed casein or soy protein diets. J. Nutr. 76: 475-482.
T. S. NELSON AND R. D. MILES Department ofAnimal Sciences, University of Arkansas, Fayetteville, Arkansas 72701 (Received for publication M a y 28, 1972)
ABSTRACT The influence of different sources of phosphorus on the metabolizable energy content of the diet was investigated. Broiler chicks were fed a rearing diet from one day to 10 days of age, and then fed the test diets for 11 days. Feces were collected on the last four days of the test period. Each treatment contained three replicates of 10 chicks each. The unsupplemented diet, which was composed primarily of corn and soybean meal, contained 0.17% non-phytate phosphorus. Chemical and feed grade phosphates were tested for their influence on energy utilization at levels to supply 0.23% phosphorus to diets containing 0.9% calcium. 0.3% chromic oxide was added to the diets as an indicating substance. Diets containing water soluble compounds had the highest metabolizable energy content when chemical grade phosphates were tested. The metabolizable energy content of the diet containing monobasic sodium orthophosphate was higher (P<0.05) than that of diets containing either brushite, monetite or hydroxyapatite. The diet that contained monobasic calcium orthophosphate had a higher (P<0.05) metabolizable energy than did the one that contained monetite in one test or the one that contained brushite in another test. The metabolizable enrgy values of diets containing feed grade phosphates composed of monetite and either brushite or monobasic calcium orthophosphate were the same as those of the water insoluble chemical grade phosphates. The metabolizable energy contents of diets containing feed grade phosphates that were derivatives of calcium fluroroapatite were lower (P<0.05) than those of diets containing hydroxyapatite or beta tribasic calcium orthophosphate. POULTRY SCIENCE 52: 481-485,1973
P
HOSPHATES available for feed formulation are primarily mono or dibasic salts of orthophosphoric acid, defluorinated rock phosphate and raw rock1 phosphate. These phosphates differ in the2 availability of the phosphorus they contain and in their chemical and physical1 properties. The availability of the phosphorus in these supplements has beenl studied extensively by numerous investigators. However, little work has beenI reported on their influence on energyf utilization by the chick. Evidence hass been published showing that phosphoruss can influence the metabolizable energyf content of the diet. Sibbald et al. (1961)) obtained differences in the metabolizablee
energy content of diets with different levels and sources of phosphoius. Nelson and Miles (1972) obtained a significant reduction in the metabolizable energy content of chick diets at low levels of non-phytate phosphorus. The objective of this study was to determine if the chemical and/or physical properties of phosphates had any effect on energy utilization by the chick. EXPERIMENTAL PROCEDURE
The experimental procedures and the composition of the basal diet used in the three experiments conducted in this study have been reported previously (Nelson and Miles, 1972). The chemical and feed
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Effect of Chemical and Physical Properties of Phosphates on Energy Utilization by Chicks
482
T. S. N E L S O N AND R. D .
TABLE 1.—Chemical and physical properties of chemical grade phosphates Phosphate
Crystalline phase
Water soluble phosphorus 1
pH
Ca(ffi>P04)2-H20 CaIIP04 CaHP04-2H20 Caj(P0 4 )2 Beta Cai(POi)2 NaH 2 P04-H20
Ca(H2P04)2-H 2 0 Monetite Brushite Apatite* Whitlockite NaHiPOi-HiO
97 3 3 5 2 99
3.5 7.4 7.8 7.4 8.7 4.7
grade phosphates used were obtained on the open market. These phosphates were analyzed for calcium, total phosphorus, orthophosphorus and water soluble phosphorus. T h e crystalline phases were determined b y X - r a y diffraction analysis. I n addition the feed grade phosphates were assayed for sodium, aluminum, iron, fluorine and magnesium. T h e p H determinations were made on 1 gm. of phosp h a t e in 100 ml. distilled water. Each phosphate was added to supply 0.23% phosphorus to provide a level of non-phytate phosphorus equivalent to 0.4% of the diet. All diets contained 0.9% calcium calculated from the analyses of the ingredients. RESULTS AND DISCUSSION
T h e crystalline phases, water soluble phosphorus contents and p H s of the chemical grade phosphates are listed in Table 1. T h e crystalline phases confirmed the identification of these phosphates. Monobasic calcium orthophosphate and monobasic sodium orthophosphate were soluble in water, and t h e solutions of these two phosphates were acid. T h e remaining phosphates were insoluble in water, and the p H of each was alkaline. T h e crystalline phases of the feed grade phosphates as determined by X-ray diffraction analysis are summarized in Table 2. Each sample contained at least two types of phosphates. T h e major phase in phosphate A was apatite with
some whitlockite also present. Phosphate B contained rhenanite as the major phase plus small amounts of both apatite and whitlockite. Phosphate C also contained some rhenanite, but less t h a n sample B. T h e major phase was whitlockite with apatite being present in minor amounts. Phosphate D contained both monobasic calcium orthophosphate and monetite in approximately equal proportions. T h e major phase in phosphate E was brushite plus a medium phase of monetite. Apatite structures and their derivatives are more complex t h a n the mono and dibasic salts of orthophosphoric acid (Mooney and Aia, 1961). A number of calcium orthophosphates, with molar C a / P ratios varying from 1.3 to over 2, exhibit apatite X - r a y diffraction p a t t e r n s . In addition certain impurities such as magnesium, manganese, iron and aluminum, all of which are present in natural materials, stabilize the structure. This stabilizing effect reduces the solubility of these phosphates in citrate solutions. The chemical analyses of the feed grade phosphates are listed in Table 3. T h e orthophosphorus, as a percent of total phosphorus, ranged from 93 to 97. Only sample D h a d an appreciable amount of water soluble phosphorus. Samples B and C were high in sodium. Variable amounts of aluminum and iron were present b u t TABLE 2.—Crystalline phases of feed grade phosphates Phase Phosphate Major A
Apatite 3
B
Rhenanite*
Medium Limestone
Minor Dolomite Whitlockite Apatite 1 Whitlockite
C
Whitlockite
Rhenanite 2
Apatite 1 Limestone
Brushite
Ca(H2P04)2-H20 Monetite Monetite
D E 1
Cas(P0 4 )8(OH,F). 2 CaeNaj(P04)5.
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1 Percent of total phosphorus, rounded to nearest whole value. * Cas(P04)i(OH).
MILES
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P H O S P H O R U S AND E N E R G Y
TABLE 3.—Chemical properties of feed grade phosphates
Phosphate A B C D E
, "tl° P
Water soluble pi
Sodium
Aluminum
Iron
Fluorine
Magnesium
%
%
%
%
%
93 96 94 95 97
1 1 1 41 4
0.64 5.64 5.52 0.05 0.04
0.58 0.47 1.22 0.88 0.87
0.75 0.90 0.84 1.43 0.09
0.44 0.14 0.04 0.14 0.09
0.96 0.23 0.30 0.54 0.02
pH 9.2 8.4 8.8 3.5 7.2
Percent of total phosphorus, rounded to nearest whole value.
neither element was abnormally high in any of the samples. Sample A contained the highest amount of fluorine. T h e fluorine content of sample C appeared to be low for this particular phosphate, however, a second analysis confirmed this low value. Sample A contained the highest level of magnesium which may reflect the presence of dolomite as a minor phase in this sample. Only sample D contained an appreciable amount of water soluble phosphorus.
structure or derivatives of apatite are summarized in Table 5. No difference occurred in the metabolizable energy content of the diets containing hydroxyapatite or whitlockite. T h e metabolizable energy content of these two diets was higher ( P < 0 . 0 5 ) t h a n t h a t of the diets containing phosphates B and C, but not A. T h e metabolizable energy content of the diet containing phosphate A fell between these extremes and not statistically different from either group.
T h e results obtained when feeding diets containing the chemical grade phosphates are given in Table 4. The metabolizable energy content of the diet containing monobasic sodium orthophosphate was higher ( P < 0 . 0 5 ) t h a n t h a t of the diets containing either monetite, brushite or hydroxyapatite. Monobasic calcium orthophosphate produced a higher ( P < 0 . 0 5 ) metabolizable energy t h a n did monetite. The comparison of the metabolizable energy contents of diets containing chemical and feed grade phosphates of apatite
T h e metabolizable energy content of diets containing monocalcium orthophosphate, monetite and brushite, and the feed grade phosphates containing mixtures of these phosphates are given in Table 6. T h e metabolizable energy content of the diet containing monocalcium orthophosphate was higher ( P < 0 . 0 5 ) t h a n t h a t of the diet containing brushite. This was a reversal of the results presented in Table 4 where the metabolizable energy values of the diets containing monocalcium orthophosphate and mone-
TABLE 4.—Effect of chemical grade phosphates on the metabolizable energy content of chick diets, experiment 1 Supplement NaHP04-HsO Ca(H2P04)2-H20 CaHPOi-2H20 Caj(P04)2 CaHPOi
Major and medium ^crystalline . i K phases S T
£&#
Monobasic sodium orthophosphate 3.37a Monobasic calcium orthophosphate 3.32ab Brushite 3.30bc Apatite 3.28bc Monetite 3.26c
1 Dry matter basis. Values not having the same superscript are statistically different (P < 0.05).
TABLE 5.—Effect of chemical and feed grade phosphates on the metabolizable energy content of chick diets, experiment 2 Supplement
Major and medium crystalline phases
M.E. of diet1 Kcal./g.
Cai(P04)2 Beta Caa(P04)2 Phosphate A Phosphate B Phosphate C
Apatite Whitlockite Apatite, whitlockite Rhenanite Whitlockite, rhenanite, apatite
3.41a 3.41a 3.36ab 3.31b 3.31b
1 Dry matter basis. Values not having the same superscript are statistically different (P < 0.05).
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T. S. NELSON AND R. D. MILES
T A B L E 6.—Effect of chemical and feed grade monobasic and dibasic calcium orthophosphate on the metabolizable energy content of chick diets, experiment 3 Major and medium crystalline phases
M.E. of diet' Kcal./g.
CaHP04 CaHPOi-2H20 Ca(H2P04)2-H20 Phosphate D
Monetite Brushite Monobasic calcium orthophosphate Monobasic calcium orthophosphate, monetite Brushite, monetite
3.53ab 3.50b 3.57a 3.53ab
Phosphate E
3.50b
1 Dry matter basis. Values not having same superscript are statisticallv different (P < 0.05).
tite, but not brushite, were different (P<0.05). The differences in the metabolizable energy content of the diets containing the test phosphates could not be attributed to differences in levels of "available" phosphorus. Based on the availability values of Nelson and Peeler (1961) and Nelson et al. (1965), none of the diets contained less than 0.3% "available" phosphorus, a level shown by Nelson and Miles (1972) to be sufficient for maximum or near maximum energy utilization. The metabolizable energy content of the diets was not influenced by the availability of the phosphorus contained in the test phosphates. This is based on the assumption that the relative biological availability of the chemical grade phosphates used in this study were similar to the values reported by Nelson et al. (1965). No differences occurred in the metabolizable energy content of the diets containing monetite and brushite (Tables 4 and 6) whereas the "available" phosphorus content of brushite is 15 to 20% greater than that of monetite. The available phosphorus content of brushite and monobasic calcium orthophosphate is similar, but the latter produced higher metabolizable energy values than the former. In addition the availability of monobasic sodium orthophosphate is similar to that of monetite and hydroxyapatite, and less
The lower metabolizable energy content of the diets containing phosphates A, B and C was not associated with any evident chemical characteristic of these samples. Phosphates B and C were high in sodium but contained less than monobasic sodium orthophosphate which produced the highest dietary metabolizable energy. The energy content of the diets containing these phosphates could not be explained on the basis of sodium, orthophosphate, aluminum, iron, fluorine, magnesium or pH. Sample A contained the highest amounts of fluorine and magnesium, but themetabolizableenergycontent of the diet containing this phosphate was similar to those of the diets containing phosphates B and C. The pH values of phosphates B and C were similar to that
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than that of monobasic calcium orthophosphate and brushite, but the diet containing the sodium compound had the highest metabolizable energy content. The two chemical grade phosphates producing the highest metabolizable energy values were both monobasic salts of orthophosphoric acid (Table 3). The higher dietary metabolizable energy of a diet containing monobasic calcium orthophosphate was confirmed in a second comparison (Table 6). Since both types of phosphates were water soluble and their solutions were acid (Table 1), the increase in metabolizable energy of the diets containing these two phosphates appeared to be related to these two properties. The water insoluble feed grade phosphates did not produce dietary metabolizable energy values any greater than the corresponding chemical grade compounds. The diet containing phosphate D, which was partially soluble in water, had a higher metabolizable energy than the diet that contained phosphate E although the difference was not statisticallv different.
485
P H O S P H O R U S AND E N E R G Y
Sibbald et al. (1961) reported t h a t the differences t h e y obtained for the m e t a b olizable energy content of diets containing various sources of phosphorus were small b u t t h e y did not preclude t h e possibility t h a t other phosphorus sources might have a beneficial or detrimental effect upon energy utilization. Because of the precision of their data, which resulted in small differences being statistically different, they expressed doubt t h a t , from a practical standpoint, the t r e a t m e n t effects were of much consequence. I n the studies reported herein, t h e degree of precision resulted in t r e a t m e n t differences of 0.07 kcal./g. being statistically significant. This is equivalent to 70 kcal./kg. which is in the range of practical significance. T h u s , these d a t a show t h a t
higher
metabolizable energy values were obtained for diets containing water soluble chemical grade phosphates. Lower values were obtained for feed grade phosphates where the crystalline phase was primarily calcium fluoroapatite or derivatives of calcium fluoroapatite. ACKNO WLED GMENT T h e authors wish to t h a n k I n t e r n a tional Minerals & Chemical Corporation for conducting a portion of the calcium and phosphorus analyses and supplying a grant-in-aid which partially supported this study. REFERENCES Mooney, R. W., and M. A. Aia, 1961. Alkaline earth phosphates. Chem. Revs. 433-462. Nelson, f. S., W. A. Hargus, N. Storer and A. C. Walker, 1965. The influence of calcium on phosphorus utilization by chicks. Poultry Sci. 44: 1508-1513. Nelson, T. S., and H. T. Peeler, 1961. The availability of phosphorus from single and combined phosphates to chicks. Poultry Sci. 40:1321-1328. Nelson, T. S., and R. D. Miles, 1972. Effect of calcium and phosphorus on energy utilization by chicks. Poultry Sci. 51: 1536-1540. Sibbald, I. R., S. J. Slinger and G. C. Ashton, 1961. Factors affecting the metabolizable energy content of poultry feeds. 4. The influences of calcium, phosphorus, antibiotics and pantothenic acid. Poultry Sci. 40: 945-951.
TOM NEWMAN MEMORIAL AWARD (Continued from page 473)
versity of Pretoria, Onderstepoort, South Africa, in 1959, an M.S. degree and a Ph.D. degree, at Michigan State University in 1965 and 1970, respectively. In 1967 he became a Diplomate of the American College of Veterinary Microbiologists. He was the recipient of the Sir Arnold Theiler Medal awarded to "the final year B.V.Sc. student who, on passing out, has shown the most diligent and meritorious achevement," the Agricura Prize for Veterinary Pathology awarded to "the final year B.V.Sc. student who has achieved the highest stan-
dard over the whole pathology course," and the Imperial Chemicals Prize awarded to "the B.V.Sc. student who has obtained the highest marks in surgery and gynaecology." In 1969 he received the Sigma Xi Graduate Student Research Award. In 1971 he was the recipient of the CPC International Award, administered by the Poultry Science Association, Inc. This award is given as an achievement award for distinctive contributions to poultry science advancement, covering a period of not more than seven years preceding the annual award.
(Continued on page 491)
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of beta tribasic calcium orthophosphate. The metabolizable energy content of the diets containing phosphates D a n d E were at least equal to t h a t of the diets containing a chemical grade phosphate with one of the crystalline phases present in the feed grade products. However, the diets containing phosphates A, B and C had energy values t h a t were either numerically or significantly lower t h a n those of t h e diets containing the chemical grade phosphates.
481
Westerfeld, W. W., D. A. Richert and A. C. Hermans, 1962. Growth and liver xanthine dehydrogenase in chicks and poults fed casein or soy protein diets. J. Nutr. 76: 475-482.
T. S. NELSON AND R. D. MILES Department ofAnimal Sciences, University of Arkansas, Fayetteville, Arkansas 72701 (Received for publication M a y 28, 1972)
ABSTRACT The influence of different sources of phosphorus on the metabolizable energy content of the diet was investigated. Broiler chicks were fed a rearing diet from one day to 10 days of age, and then fed the test diets for 11 days. Feces were collected on the last four days of the test period. Each treatment contained three replicates of 10 chicks each. The unsupplemented diet, which was composed primarily of corn and soybean meal, contained 0.17% non-phytate phosphorus. Chemical and feed grade phosphates were tested for their influence on energy utilization at levels to supply 0.23% phosphorus to diets containing 0.9% calcium. 0.3% chromic oxide was added to the diets as an indicating substance. Diets containing water soluble compounds had the highest metabolizable energy content when chemical grade phosphates were tested. The metabolizable energy content of the diet containing monobasic sodium orthophosphate was higher (P<0.05) than that of diets containing either brushite, monetite or hydroxyapatite. The diet that contained monobasic calcium orthophosphate had a higher (P<0.05) metabolizable energy than did the one that contained monetite in one test or the one that contained brushite in another test. The metabolizable enrgy values of diets containing feed grade phosphates composed of monetite and either brushite or monobasic calcium orthophosphate were the same as those of the water insoluble chemical grade phosphates. The metabolizable energy contents of diets containing feed grade phosphates that were derivatives of calcium fluroroapatite were lower (P<0.05) than those of diets containing hydroxyapatite or beta tribasic calcium orthophosphate. POULTRY SCIENCE 52: 481-485,1973
P
HOSPHATES available for feed formulation are primarily mono or dibasic salts of orthophosphoric acid, defluorinated rock phosphate and raw rock1 phosphate. These phosphates differ in the2 availability of the phosphorus they contain and in their chemical and physical1 properties. The availability of the phosphorus in these supplements has beenl studied extensively by numerous investigators. However, little work has beenI reported on their influence on energyf utilization by the chick. Evidence hass been published showing that phosphoruss can influence the metabolizable energyf content of the diet. Sibbald et al. (1961)) obtained differences in the metabolizablee
energy content of diets with different levels and sources of phosphoius. Nelson and Miles (1972) obtained a significant reduction in the metabolizable energy content of chick diets at low levels of non-phytate phosphorus. The objective of this study was to determine if the chemical and/or physical properties of phosphates had any effect on energy utilization by the chick. EXPERIMENTAL PROCEDURE
The experimental procedures and the composition of the basal diet used in the three experiments conducted in this study have been reported previously (Nelson and Miles, 1972). The chemical and feed
Downloaded from http://ps.oxfordjournals.org/ at Centro de Estudos Do Hospital Felicio Rocho on August 14, 2015
Effect of Chemical and Physical Properties of Phosphates on Energy Utilization by Chicks
482
T. S. N E L S O N AND R. D .
TABLE 1.—Chemical and physical properties of chemical grade phosphates Phosphate
Crystalline phase
Water soluble phosphorus 1
pH
Ca(ffi>P04)2-H20 CaIIP04 CaHP04-2H20 Caj(P0 4 )2 Beta Cai(POi)2 NaH 2 P04-H20
Ca(H2P04)2-H 2 0 Monetite Brushite Apatite* Whitlockite NaHiPOi-HiO
97 3 3 5 2 99
3.5 7.4 7.8 7.4 8.7 4.7
grade phosphates used were obtained on the open market. These phosphates were analyzed for calcium, total phosphorus, orthophosphorus and water soluble phosphorus. T h e crystalline phases were determined b y X - r a y diffraction analysis. I n addition the feed grade phosphates were assayed for sodium, aluminum, iron, fluorine and magnesium. T h e p H determinations were made on 1 gm. of phosp h a t e in 100 ml. distilled water. Each phosphate was added to supply 0.23% phosphorus to provide a level of non-phytate phosphorus equivalent to 0.4% of the diet. All diets contained 0.9% calcium calculated from the analyses of the ingredients. RESULTS AND DISCUSSION
T h e crystalline phases, water soluble phosphorus contents and p H s of the chemical grade phosphates are listed in Table 1. T h e crystalline phases confirmed the identification of these phosphates. Monobasic calcium orthophosphate and monobasic sodium orthophosphate were soluble in water, and t h e solutions of these two phosphates were acid. T h e remaining phosphates were insoluble in water, and the p H of each was alkaline. T h e crystalline phases of the feed grade phosphates as determined by X-ray diffraction analysis are summarized in Table 2. Each sample contained at least two types of phosphates. T h e major phase in phosphate A was apatite with
some whitlockite also present. Phosphate B contained rhenanite as the major phase plus small amounts of both apatite and whitlockite. Phosphate C also contained some rhenanite, but less t h a n sample B. T h e major phase was whitlockite with apatite being present in minor amounts. Phosphate D contained both monobasic calcium orthophosphate and monetite in approximately equal proportions. T h e major phase in phosphate E was brushite plus a medium phase of monetite. Apatite structures and their derivatives are more complex t h a n the mono and dibasic salts of orthophosphoric acid (Mooney and Aia, 1961). A number of calcium orthophosphates, with molar C a / P ratios varying from 1.3 to over 2, exhibit apatite X - r a y diffraction p a t t e r n s . In addition certain impurities such as magnesium, manganese, iron and aluminum, all of which are present in natural materials, stabilize the structure. This stabilizing effect reduces the solubility of these phosphates in citrate solutions. The chemical analyses of the feed grade phosphates are listed in Table 3. T h e orthophosphorus, as a percent of total phosphorus, ranged from 93 to 97. Only sample D h a d an appreciable amount of water soluble phosphorus. Samples B and C were high in sodium. Variable amounts of aluminum and iron were present b u t TABLE 2.—Crystalline phases of feed grade phosphates Phase Phosphate Major A
Apatite 3
B
Rhenanite*
Medium Limestone
Minor Dolomite Whitlockite Apatite 1 Whitlockite
C
Whitlockite
Rhenanite 2
Apatite 1 Limestone
Brushite
Ca(H2P04)2-H20 Monetite Monetite
D E 1
Cas(P0 4 )8(OH,F). 2 CaeNaj(P04)5.
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1 Percent of total phosphorus, rounded to nearest whole value. * Cas(P04)i(OH).
MILES
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P H O S P H O R U S AND E N E R G Y
TABLE 3.—Chemical properties of feed grade phosphates
Phosphate A B C D E
, "tl° P
Water soluble pi
Sodium
Aluminum
Iron
Fluorine
Magnesium
%
%
%
%
%
93 96 94 95 97
1 1 1 41 4
0.64 5.64 5.52 0.05 0.04
0.58 0.47 1.22 0.88 0.87
0.75 0.90 0.84 1.43 0.09
0.44 0.14 0.04 0.14 0.09
0.96 0.23 0.30 0.54 0.02
pH 9.2 8.4 8.8 3.5 7.2
Percent of total phosphorus, rounded to nearest whole value.
neither element was abnormally high in any of the samples. Sample A contained the highest amount of fluorine. T h e fluorine content of sample C appeared to be low for this particular phosphate, however, a second analysis confirmed this low value. Sample A contained the highest level of magnesium which may reflect the presence of dolomite as a minor phase in this sample. Only sample D contained an appreciable amount of water soluble phosphorus.
structure or derivatives of apatite are summarized in Table 5. No difference occurred in the metabolizable energy content of the diets containing hydroxyapatite or whitlockite. T h e metabolizable energy content of these two diets was higher ( P < 0 . 0 5 ) t h a n t h a t of the diets containing phosphates B and C, but not A. T h e metabolizable energy content of the diet containing phosphate A fell between these extremes and not statistically different from either group.
T h e results obtained when feeding diets containing the chemical grade phosphates are given in Table 4. The metabolizable energy content of the diet containing monobasic sodium orthophosphate was higher ( P < 0 . 0 5 ) t h a n t h a t of the diets containing either monetite, brushite or hydroxyapatite. Monobasic calcium orthophosphate produced a higher ( P < 0 . 0 5 ) metabolizable energy t h a n did monetite. The comparison of the metabolizable energy contents of diets containing chemical and feed grade phosphates of apatite
T h e metabolizable energy content of diets containing monocalcium orthophosphate, monetite and brushite, and the feed grade phosphates containing mixtures of these phosphates are given in Table 6. T h e metabolizable energy content of the diet containing monocalcium orthophosphate was higher ( P < 0 . 0 5 ) t h a n t h a t of the diet containing brushite. This was a reversal of the results presented in Table 4 where the metabolizable energy values of the diets containing monocalcium orthophosphate and mone-
TABLE 4.—Effect of chemical grade phosphates on the metabolizable energy content of chick diets, experiment 1 Supplement NaHP04-HsO Ca(H2P04)2-H20 CaHPOi-2H20 Caj(P04)2 CaHPOi
Major and medium ^crystalline . i K phases S T
£&#
Monobasic sodium orthophosphate 3.37a Monobasic calcium orthophosphate 3.32ab Brushite 3.30bc Apatite 3.28bc Monetite 3.26c
1 Dry matter basis. Values not having the same superscript are statistically different (P < 0.05).
TABLE 5.—Effect of chemical and feed grade phosphates on the metabolizable energy content of chick diets, experiment 2 Supplement
Major and medium crystalline phases
M.E. of diet1 Kcal./g.
Cai(P04)2 Beta Caa(P04)2 Phosphate A Phosphate B Phosphate C
Apatite Whitlockite Apatite, whitlockite Rhenanite Whitlockite, rhenanite, apatite
3.41a 3.41a 3.36ab 3.31b 3.31b
1 Dry matter basis. Values not having the same superscript are statistically different (P < 0.05).
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T. S. NELSON AND R. D. MILES
T A B L E 6.—Effect of chemical and feed grade monobasic and dibasic calcium orthophosphate on the metabolizable energy content of chick diets, experiment 3 Major and medium crystalline phases
M.E. of diet' Kcal./g.
CaHP04 CaHPOi-2H20 Ca(H2P04)2-H20 Phosphate D
Monetite Brushite Monobasic calcium orthophosphate Monobasic calcium orthophosphate, monetite Brushite, monetite
3.53ab 3.50b 3.57a 3.53ab
Phosphate E
3.50b
1 Dry matter basis. Values not having same superscript are statisticallv different (P < 0.05).
tite, but not brushite, were different (P<0.05). The differences in the metabolizable energy content of the diets containing the test phosphates could not be attributed to differences in levels of "available" phosphorus. Based on the availability values of Nelson and Peeler (1961) and Nelson et al. (1965), none of the diets contained less than 0.3% "available" phosphorus, a level shown by Nelson and Miles (1972) to be sufficient for maximum or near maximum energy utilization. The metabolizable energy content of the diets was not influenced by the availability of the phosphorus contained in the test phosphates. This is based on the assumption that the relative biological availability of the chemical grade phosphates used in this study were similar to the values reported by Nelson et al. (1965). No differences occurred in the metabolizable energy content of the diets containing monetite and brushite (Tables 4 and 6) whereas the "available" phosphorus content of brushite is 15 to 20% greater than that of monetite. The available phosphorus content of brushite and monobasic calcium orthophosphate is similar, but the latter produced higher metabolizable energy values than the former. In addition the availability of monobasic sodium orthophosphate is similar to that of monetite and hydroxyapatite, and less
The lower metabolizable energy content of the diets containing phosphates A, B and C was not associated with any evident chemical characteristic of these samples. Phosphates B and C were high in sodium but contained less than monobasic sodium orthophosphate which produced the highest dietary metabolizable energy. The energy content of the diets containing these phosphates could not be explained on the basis of sodium, orthophosphate, aluminum, iron, fluorine, magnesium or pH. Sample A contained the highest amounts of fluorine and magnesium, but themetabolizableenergycontent of the diet containing this phosphate was similar to those of the diets containing phosphates B and C. The pH values of phosphates B and C were similar to that
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Supplement
than that of monobasic calcium orthophosphate and brushite, but the diet containing the sodium compound had the highest metabolizable energy content. The two chemical grade phosphates producing the highest metabolizable energy values were both monobasic salts of orthophosphoric acid (Table 3). The higher dietary metabolizable energy of a diet containing monobasic calcium orthophosphate was confirmed in a second comparison (Table 6). Since both types of phosphates were water soluble and their solutions were acid (Table 1), the increase in metabolizable energy of the diets containing these two phosphates appeared to be related to these two properties. The water insoluble feed grade phosphates did not produce dietary metabolizable energy values any greater than the corresponding chemical grade compounds. The diet containing phosphate D, which was partially soluble in water, had a higher metabolizable energy than the diet that contained phosphate E although the difference was not statisticallv different.
485
P H O S P H O R U S AND E N E R G Y
Sibbald et al. (1961) reported t h a t the differences t h e y obtained for the m e t a b olizable energy content of diets containing various sources of phosphorus were small b u t t h e y did not preclude t h e possibility t h a t other phosphorus sources might have a beneficial or detrimental effect upon energy utilization. Because of the precision of their data, which resulted in small differences being statistically different, they expressed doubt t h a t , from a practical standpoint, the t r e a t m e n t effects were of much consequence. I n the studies reported herein, t h e degree of precision resulted in t r e a t m e n t differences of 0.07 kcal./g. being statistically significant. This is equivalent to 70 kcal./kg. which is in the range of practical significance. T h u s , these d a t a show t h a t
higher
metabolizable energy values were obtained for diets containing water soluble chemical grade phosphates. Lower values were obtained for feed grade phosphates where the crystalline phase was primarily calcium fluoroapatite or derivatives of calcium fluoroapatite. ACKNO WLED GMENT T h e authors wish to t h a n k I n t e r n a tional Minerals & Chemical Corporation for conducting a portion of the calcium and phosphorus analyses and supplying a grant-in-aid which partially supported this study. REFERENCES Mooney, R. W., and M. A. Aia, 1961. Alkaline earth phosphates. Chem. Revs. 433-462. Nelson, f. S., W. A. Hargus, N. Storer and A. C. Walker, 1965. The influence of calcium on phosphorus utilization by chicks. Poultry Sci. 44: 1508-1513. Nelson, T. S., and H. T. Peeler, 1961. The availability of phosphorus from single and combined phosphates to chicks. Poultry Sci. 40:1321-1328. Nelson, T. S., and R. D. Miles, 1972. Effect of calcium and phosphorus on energy utilization by chicks. Poultry Sci. 51: 1536-1540. Sibbald, I. R., S. J. Slinger and G. C. Ashton, 1961. Factors affecting the metabolizable energy content of poultry feeds. 4. The influences of calcium, phosphorus, antibiotics and pantothenic acid. Poultry Sci. 40: 945-951.
TOM NEWMAN MEMORIAL AWARD (Continued from page 473)
versity of Pretoria, Onderstepoort, South Africa, in 1959, an M.S. degree and a Ph.D. degree, at Michigan State University in 1965 and 1970, respectively. In 1967 he became a Diplomate of the American College of Veterinary Microbiologists. He was the recipient of the Sir Arnold Theiler Medal awarded to "the final year B.V.Sc. student who, on passing out, has shown the most diligent and meritorious achevement," the Agricura Prize for Veterinary Pathology awarded to "the final year B.V.Sc. student who has achieved the highest stan-
dard over the whole pathology course," and the Imperial Chemicals Prize awarded to "the B.V.Sc. student who has obtained the highest marks in surgery and gynaecology." In 1969 he received the Sigma Xi Graduate Student Research Award. In 1971 he was the recipient of the CPC International Award, administered by the Poultry Science Association, Inc. This award is given as an achievement award for distinctive contributions to poultry science advancement, covering a period of not more than seven years preceding the annual award.
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of beta tribasic calcium orthophosphate. The metabolizable energy content of the diets containing phosphates D a n d E were at least equal to t h a t of the diets containing a chemical grade phosphate with one of the crystalline phases present in the feed grade products. However, the diets containing phosphates A, B and C had energy values t h a t were either numerically or significantly lower t h a n those of t h e diets containing the chemical grade phosphates.