Animal Husbandry Mimeograph June, 1957
Series No. 57-6

UTILIZATION OF PHOSPHORUS FROM DIFFERENT SOURCES BY RATS

L. R. Arrington, D. C. Bowen and D. C. Tomlin1


A number of phosphatic materials are available and produced

in Florida which can be used as supplements in livestock and poul-

try rations. An important measure of the value of these materials

as phosphorus sources is the utilization by animals. Barrentine,

Maynard and Loosli (1) and Ellis et al (3) have studied the utili-

zation of certain inorganic phosphorus supplements by rats and

found that inorganic sources were useful, but that there were dif-

ferences in utilization. These results were based in part upon

growth and bone ash of the rats. Similar experiments have been

conducted with poultry and swine using these criteria as a meas-

ure of utilization (2, 4, 5, 6, 7).

This experiment was designed to study the comparative utili-

zation, by rats, of three inorganic phosphates, two of which were

produced in Florida.


Procedure'


Defluorinated rock phosphate, soft phosphate with colloidal\

clay and reagent grade dicalcium phosphate (CaHP04) were used

separately to supply approximately two-thirds of the phosphorus

requirement. Defluorinated phosphate and soft phosphate were test

substances, and the calcium phosphate was used as the reference

standard. These were added to a semi-purified diet made of corn


1Arrington, Assistant Animal Nutritionist; Bowen, Student
Assistant; Tomlin, Research Assistant, Department of Animal Hus-
bandry and Nutrition.








-2-


meal 30 parts, casein 10, albumen 5, sucrose 20, starch 20,

vegetable oil 6, alphacel 5, Brewers yeast 1, vitamin mix 1 and

NaC1 1. The basal diet contained 0.13 percent phosphorus. Using

this basal diet, additional dietary treatments were prepared by

adding the supplements in amounts which provided 0.20 percent

phosphorus making a total of 0.33 percent phosphorus in each of

the experimental diets. Thus, more than half of the phosphorus

intake was supplied by the supplements. The phosphorus require-

ment for the rat is approximately 0.4 percent, but the intake from

the experimental diets was kept low so that maximum utilization

would be possible. Calcium carbonate was added to adjust the cal-

cium to phosphorus ratio at 1.8 to 1.

Forty-eight weanling rats of the Long-Evans strain, 22-24

days of age were used as experimental animals. They were divided

into four groups of seven males and five females each. Animals

were housed in metal cages with raised screen bottoms in a room

with the temperature controlled at 780 F. Experimental diets and

fresh water were supplied ad libitum and the total feed consumed

by each group was measured. After six weeks on the experiment

(nine weeks of age), the rats were sacrificed and both femur

bones removed for use in bone ash determinations. Bones were

freed of adhering tissue, dried for 24 hours at 1050 C then ashed

in a muffle furnace for 24 hours at 6000 C. The rats were sacri-

ficed after six weeks on experiment so that bone ash determinations

would represent rats in an actively growing state.










Results


Growth data in terms of weight gain at three and six weeks,

feed efficiency, total bone ash and femur size are recorded in

Table I. Rats which were fed the basal diet without any supple-

mentation gained less and accumulated less total ash in the bones

than did those which were supplemented. Each of the phosphorus

supplements promoted greater gains and increased bone ash demon-

strating the utilization of phosphorus from these sources.


STABLE I


Weight Gain, Feed Efficiency, Bone Ash and Femur
Size of Rats Fed Phosphorus from Different Sources

Source Av. live wt. Grams feed/ Bone ash Femur size
Gains (grams) Gram gain (%) (% body wt.)
3 wks 6 wks

Basal 43 107 4.7 48.3 .279
Soft
Phosphate 72 168 3.1 56.4 .301
Defluorinated 76 175 3.2 58.5 .310
Phosphate
CaHP04 84 185 3.0 60.0 .319


Although each of the supplements was utilized, there were

differences in availability or utilization which were reflected

in growth and bone ash values. Phosphorus in CaHPO4 was most avail-

able followed by defluorinated phosphate and soft phosphate. If

the value for CaHPO4 is arbitrarily placed at 100, then the rela-

tive value for defluorinated phosphate would be 94 percent as

available based on weight gain and 97 on bone ash. Using the same












comparison, the values for soft phosphate would be 91 and 94.

Using these criteria of measurement with rats, the avail-

ability of phosphorus in soft phosphate was greater than has

been indicated for chicks. It may be that there is a species

difference and that phosphorus in soft phosphate is relatively

more available to rats. It may be that the minimum phosphorus

requirement for the growing rat is much less than that supplied

and that the supplemental phosphates were not called upon or not

needed in full to supply needed phosphorus. On the other hand,

those rats on the basal diet which was not supplemented made poor

gains and had much less bone ash than those which were supple-

mented. This demonstrates that additional phosphorus was needed

and that it was available from each of the phosphate supplements.












References


1. Barrentine, B. F., L. A. Maynard and J. K. Loosli. 1944.
The availability of the calcium and phosphorus of defluori-
nated rock phosphate for the rat. J. Nutrition 27: 35.

2. Chapman, H. L., Jr., J. Kastelic, G. C. Ashton and D. V.
Catron. 1955. A comparison of phosphorus from different
sources for growing and finishing swine. J. Animal Sci.
14: 1073.

3. Ellis, N. R., C. A. Cabell, W. P. Elmslie, G. S. Fraps,
P. H. Phillips and Dorothy E. Williams. 1945. Nutritive
evaluation of defluorinated phosphates and other phosphorus
supplements. III. Utilization experiments with rats. J.
Assoc. Official Agr. Chem. 28: 129.

4. Gillis, M. B., L. C. Norris and G. F. Heuser. 1954. Studies
on the Biological value of inorganic phosphates. J. Nutrition
52: 115.

5. Gobble, J. L., R. C. Miller, G. W. Sherritt and H. W. Dunne.
1956. Soft phosphate with colloidal clay as a source of
phosphorus for growing and fattening pigs. Pa. Agr. Expt.
Sta. Bull. 609.

6. Grau, C. R. and Phyllis A. Zweigart. 1953. Phosphatic clay
as a phosphorus source for chicks. Poultry Sci. 32: 500.

7. Wilcox, R. A., C. W. Carlson, W. Kohlmeyer and G. F. Gastler.
1954. The availability of phosphorus from different sources
for poults fed purified diets. Poultry Sci. 33: 1910