BRANION (1938) concluded that the

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1 PHOSPHORUS REQUIREMENTS 47 "normal" parents. Poultry Sci. 33: Lee, A. M., L. H. Scrivner and M. O. North, Avian leukosis and lymphomatosis. Wyoming Agr. Exper. Sta. Bull. 66. Simms, H. S., and M. Sanders, 194. Use of serum ultrafiltrate in tissue cultures for studying deposition of fat and for propagation of viruses. Arch. Path. 33: Waters, N. F., and C. 0. Prickett, The devel- opment of families of chickens free of lymphomatosis. Poultry Sci. 3: Waters, N. F., and J. H. Bywaters, Influence of age of chickens at contact exposure on incidence of lymphomatosis. Poultry Sci. 8: Waters, N. F., 194. Etiological relationship of visceral and neural lymphomatosis. Poultry Sci. 33: The Phosphorus Requirements of Growing Chickens and Laying Pullets Fed Practical Rations BRANION (1938) concluded that the ratio of calcium to phosphorus was not of prime importance to the growing chicken when vitamin D was present at an optimal level. With adequate vitamin D and reasonable levels of calcium and phosphorus the Ca:P ratio could vary from 1:1 to 3:1 with an optimum of :1. However, the absolute amounts of calcium and phosphorus were important for optimal growth and bone ash. The amount of phosphorus required was stated as 0.4 percent and to insure an adequate amount 0. percent was recommended. Since this review, considerable evidence has accumulated indicating that the phosphorus requirement of the growing chicken is greater than 0.4 per cent. Couch et al. (1937) suggested that a level of 0.76 to 0.81 percent phosphorus was adequate for normal growth and calcification of chicks up to twelve weeks of age. Lowe et al. (1939) concluded that much of Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Supported in part by a grant from the Murphy Products Co., Burlington, Wisconsin. 1 Present address, Gooch Feed Mill Co., Salina, Kansas. Present address, McMillen Feed Mills, Decatur, Indiana. W. F. O'ROURKE, 1 P. H. PHILLIPS AND W. W. CRAVENS (Received for publication March, 194) the work done in the past on Ca: P ratios was complicated by the low availability of phytin phosphorus. Nowotarski and Bird (1943) reported that the amount of phosphorus required for maximum growth, bone ash and prevention of rickets was greater than 0. percent and that vitamin D reduced the amount of minerals needed for best results. Heuser et al. (1943) found that supplementation of soybean oil meal rations with inorganic phosphorus was necessary for optimum growth and bone ash. It was stated that phytin phosphorus was not available for normal bone formation and growth. Consequently all-grain rations required supplementation with an inorganic phosphorus source. Singsen and Mitchell (1944) reported that if unheated leafy material containing phytase activity was incorporated into all-plant rations, no supplementary phosphorus was needed. Their estimated requirement of 0.4 percent agreed well with the conclusion of Branion. Coincident with this report McGinnis et al. (1944) found that phytin phosphorus of cereals and legumes was not utilized as effectively as inorganic phosphorus when they compared a practical ration with a purified ration contain-

2 48 W. F. O'ROURKE, P. H. PHILLIPS AND W. W. CRAVENS ing the same level of phosphorus. They also showed that as the amount of vitamin D increased, the utilization of phytin phosphorus increased. However, no amount of vitamin D would increase bone ash to the level obtained with inorganic phosphorus supplementation. Carver et al. (1946) obtained optimal results when the diet contained 1.6 percent calcium and 0.8 percent phosphorus. Gillis et al. (1949) used purified and practical rations and concluded that optimum early growth and bone formation were obtained with 0.6 percent phosphorus in the ration of which 0.4 percent had to be nonphytin phosphorus. The National Reasearch Council (190) revised its recommendations on the basis of this work. O'Rourke et al. (19) determined the phosphorus requirement of growing chickens fed a purified basal ration. It was shown that their requirement decreased with age. Since these findings appeared to have economic possibilities similar research was undertaken with practical rations which contain a part of their phosphorus in the form of relatively unavailable phytin. Since the nutrition of the young growing animal may affect the production of the mature animal, other experiments were initiated to determine whether this is true of phosphorus nutrition of chickens. Research was conducted to determine the effect of early phosphorus nutrition on the productive behavior of the laying pullet as well as to determine the requirement of the laying pullet for phosphorus. A review of the pertinent literature in respect to the phosphorus requirement of the laying pullet has been presented elsewhere. (O'Rourke et al., 194). It suffices to say that the requirement for phosphorus by the laying pullet has not been clearly established. Much of the early research was carried out with a fixed level of calcium in the ration. The calcium level was not fixed in the rations of the experiments to be reported here. Oyster shell was supplied ad libitum. EXPERIMENTAL Experiment 1. This experiment was conducted to determine the very early requirement for phosphorus by the growing chicken. Groups of ten, crossbred (N.H. X S.C.W.L.) chicks of both sexes were placed in conventional battery brooders with feed and water supplied ad libitum. The basal ration is shown in Table 1 under the heading of experiment 1. Bone meal was added to the basal ration at the expense of the corn to provide rations with phosphorus levels of 0.38, 0.48, 0.9 and 0.73 percent. The basal ration contained 0.33 percent phosphorus, all from plant sources. The chickens were weighed at weekly intervals and were sacrificed at the end of three weeks. The data are summarized in Table. The data indicate that at least 0.73 percent phosphorus was required. Since growth did not plateau, the requirement to three weeks of age must be at least 0.73 percent phosphorus. Experiment. The purpose of this experiment was to determine the phosphorus requirement of chickens between the ages of four and ten weeks. Crossbred (N.H.XS.C.W.L.) chickens of both sexes were raised to four weeks of age on a starting ration optimum for growth. At the end of the pre-experimental period the chickens were weighed and divided into six groups of twelve chickens each so that groups of equal weight were obtained. The chickens were placed in conventional growing batteries with feed and water supplied ad libitum. At the end of ten weeks the chickens were sexed,

3 PHOSPHORUS REQUIREMENTS 49 TABLE 1.The composition of the basal rations Experiment Ground yellow corn Soybean oil meal Corn gluten meal Alfalfa meal Wheat bran Standard wheat middlings Ground oyster shell Granite grit Salt (Iodized) Feeding oil (1.00A-300D) Riboflavin (mg./kg.) MnS0 4 -H 0 (mg./kg.) CaC0 3 Fish solubles Ca pantothenate (mg./kg.) Niacin (mg./kg.) Choline chloride Oyster shell B1 and antibiotic supplement (gm./kg.) * Lederle APF. 1 Maintained at 1.0% calcium. Merck 3. 3 Merck * Phosphorus in rations (%) week weight (gm.) * I ad libitum i , 6 and ad libitum l blood samples taken by the heart probe The weights in Table 3 are average method of Sloan and Wilgus (1930) and weights of cockerels and pullets: both sacrificed to obtain the left tibiae for bone sexes responded similarly to the phosphorus level fed. Weight, inorganic blood ash analysis. The blood samples were treated as follows: two cc. of blood were phosphorus, and bone ash all indicate that mixed with 8 cc. of 10 percent trichloroacetic acid. The blood-trichloroacetic acid The phosphorus requirement of the chick 0.60 percent phosphorus was sufficient. mixtures from single birds of an experimental group were pooled and filtered greater than 0.60 percent which is a deen from four through ten weeks is no through ashless filter paper. The filtrate crease in requirement when compared was analyzed for phosphorus by the Fiske with the 0.73 percent required during the and Subbarow (19) method adapted for first 3 weeks of life. the Evelyn photoelectric colorimeter. The Experiment 3. The purpose of this experiment was to ascertain the phosphorus basal ration is presented in Table 1 under the heading of experiment. Calcium acid requirement of pullets from ten weeks until sexual maturity and also to study the phosphate was used as the phosphorus supplement and was added at the expense effect of the level of phosphorus on egg of the corn. The basal ration contained production percent phosphorus. The data of this Ten week old pullets raised on a ration experiment are presented in Table 3. optimum for growth and bone ash were placed in a conventional growing battery. TABLE.The effect of the level of phosphorus on Each experimental group was composed growth of three week old chickens of sixteen pullets. When the pullets were eighteen weeks old they were transferred to an individual-cage laying battery where

4 0 W. F. O'ROURKE, P. H. PHILLIPS AND W. W. CRAVENS TABLE 3.Inorganic blood phospho affected by the amount of s, growth and percent bone ash as tosphorus in the ration Phosphorus in ration (%) week weight (gm.) Bone ash (%) Mg. of Phosphorus per 100 cc. of blood ,030 1,00 1,031 1, date of first egg and egg production could be easily determined. Feed and water were supplied ad libitum. The composition of the basal ration is presented in Table 1 under the heading of experiment 3. Calcium acid phosphate was added to the basal ration, which contained 0.4 percent phosphorus, at the expense of the corn. The rations contained 0.1, 0.61, 0.71 and 0.81 percent phosphorus. Calcium carbonate was added to the rations to maintain the calcium level at one percent. At eighteen weeks the composition of the basal ration was altered by adding 0. percent of fish oil and by removing the calcium carbonate. The difference was compensated by adding ground yellow corn. Oyster shell was fed ad libitum thereafter. The experiment was terminated when the pullets were 4 weeks old. Table 4 presents the data from this experiment. The growth of the pullets to twenty weeks may have been improved by phosphorus supplementation. However, by thirty weeks the growth data of the pullets fed the basal ration, which contained 0.4 percent phosphorus, indicated no Weeks phosphorus in ration Ave. wt. (gms.) ,03 1,00 1,06 1,31 1,3 1,818,1 1,8,1 1,877,161 1,86,04 1,890,17 need for phosphorus supplementation. Further, date of first egg and mortality data support the contention that the level of phosphorus required was not more than supplied by the basal ration. On casual observation the egg production data indicate that there was an effect due to the level of phosphorus fed. This difference was analyzed statistically by the method of variance (Snedecor, 1946). When the egg production of the pullets fed the basal ration was compared with the egg production of the group fed 0.81 percent phosphorus the f value was.3. The f value needed for significance was 4.1. Therefore, the effect of phosphorus supplementation was nonsignificant. The phosphorus requirement of pullets after ten weeks of age was not greater than 0.4 percent which indicates that the phosphorus requirement had decreased farther with decreased growth rate or increased age and that egg production did not increase the requirement measurably. Experiment 4. Since the three previous experiments were not similar in all re- TABLE 4.The effect of the level of dietary phosphorus after 10 weeks of age upon growth, date of first egg, mortality and egg production of pullets Ave. date Total Egg 4 of first mortality production egg % %, , , , ,

5 PHOSPHORUS REQUIREMENTS 1 spects and since it would be difficult to correlate the findings for practical application a further experiment was designed. Sixty-six, day old S.C.W.L. chicks of both sexes were placed in each of seven experimental groups. One brooder house with adjoining sand lot was used for each group. Feed and water were supplied ad libitum. The basal ration is shown in Table 1 under the heading of experiment 4. The basal ration, which contained 0.40 percent phosphorus, was supplemented with CaHP04-H 0 to increase the level of phosphorus in the rations. Calcium carbonate was added to maintain the calcium level at one percent of the ration. Groups 1,, 3 and 4 received 0.7 percent phosphorus while group received the basal ration. Groups 6 and 7 received 0.0 and 0.60 percent phosphorus respectively. After eight weeks the basal ration was altered by reducing the amount of soybean oil meal and by adding an equal amount of corn which gave a ration containing 18 percent protein. This basal ration contained 0.38 percent phosphorus. Therefore all the rations other than the basal ration were supplemented with additional CaHPOvH0 to maintain the level of phosphorus at the level previously described. This procedure was followed whenever the level of phosphorus in the basal ration was reduced by the removal of soybean oil meal. The cockerels were removed from the experiment at eight weeks and were sacrificed. Their left tibiae were removed for bone ash determinations as described by the A.O.A.C. (194). The pullets in groups, 6 and 7 were arranged by weight within their respective group. Equal numbers of the lightest and heaviest pullets were removed until eighty pullets remained. The remaining pullets were divided into four groups of equal weight. This reduction in the number of pullets per group was necessitated by limited space. After eight weeks, groups 4 and 6 received 0.0 percent phosphorus, 7 and, 0.60 percent, and 3, the basal ration and 1, 0.7 percent. At twelve weeks the ration was altered by reducing the amount of soybean oil meal and by increasing the corn an equal amount. The basal ration contained 16.3 percent protein and 0.37 percent phosphorus. The laying pens contained only sixteen pullets each. Four pullets were randomly selected from each group and were removed from the experiment at eighteen weeks. At the same time the level of protein was reduced to 1. percent and CaCC>3 was removed from the rations. Corn replaced the soybean oil meal and CaCC>3. Thereafter oyster shell was supplied ad libitum. The basal ration contained 0.3 percent phosphorus. The pullets were trap-nested in order to determine date of first egg and egg production. The procedure employed in this experiment was designed to simulate conditions in practice. It is common for pullets to be placed on range at eight weeks of age. Therefore the change in the level of phosphorus fed was made at eight weeks even though range was not available. To simulate range conditions and also to follow the practice of feeding increasing amounts of grain the protein level was reduced at frequent intervals. Table presents the data for the first eight weeks of the experiment. TABLE S.The effect of the level of phosphorus fed on growth and percent bone ash of eight week old chickens % Phosphorus in ration Ave. wt. of pullets (gms.) Ave. wt. of cockerels (gms.) % Bone ash (cockerels) 1,,3, Group number

6 W. F. O'ROURKE, P. H. PHILLIPS AND W. W. CRAVENS TABLE 6.The effect of the level of phosphorus fed on growth, date of first egg, percent egg production and egg weight Weeks of Weeks of age Egg ,049 1,769,60, Group number treatment (% phosphorus) Ave. pullet weight (gms.) 1, , ,041 1,780 1,688 1,774 1,470 1,70 1,7,14,040,0,101,173,34,98,3,34,08,86,367 Ave. Age at First egg (days) % egg production to 40 weeks Ave. egg weight (gms.) The growth of the pullets was optimum when 0.60 percent phosphorus was fed but the cockerels required at least 0.7 percent phosphorus for maximum growth. When bone ash was used as the criterion 0.60 percent phosphorus was sufficient. However, practical considerations would dictate a level of 0.7 percent to support optimal growth of the cockerels. Table 6 presents the rest of the data for experiment 4. The growth data indicate that by twenty weeks only the groups fed the basal ration were adversely affected by the level of phosphorus fed. However, by forty weeks both groups that received the basal ration had reached normal mature body weight. Age at first egg, percent egg production and egg weight were not affected by the level of phosphorus fed. Group 7 was adversely affected but this effect cannot be ascribed to the phosphorus level fed. Experiments, 6 and 7. These experiments were conducted to determine the phosphorus requirement of laying pullets that had not been previously subjected to an experimental regimen. S.C.W.L. pullets raised on range were used in these experiments. The pullets were selected on the basis of pre-experimental egg production and divided into groups of equal egg laying potential. They were maintained in standard individual cage laying batteries and were supplied feed, water and oyster shell ad libitum. The pullets were artificially inseminated weekly with pooled semen from New Hampshire cockerels. The eggs were pedigree marked and incubated weekly. The composition of the basal ration is shown in Table 1 under the heading of experiments, 6 and 7. Special steamed bone meal was the phosphorus supplement used in experiment while CaHPC"4 HO supplemented the basal ration in experiments 6 and 7. The egg production data are presented in Table 7. These data confirm those of experiments 3 and 4 in that the unsupplemented basal ration supported normal egg production. However, it is impossible to state the requirement for phosphorus by the laying pullet as the basal ration was not limiting. These results are interesting as they contradict the results and recommendations of most investigators. It should be emphasized that most investigators controlled the level of calcium fed to their laying birds while the pullets in the experiments reported herein were supplied oyster shell free choice. Hatchability was maintained at a normal level by all groups. TABLE 7.The effect of the level of phosphorus fed on egg production % phosphorus in the ration No. of pullets/group No. of weeks on experiment Experiment number % production

7 PHOSPHORUS REQUIREMENTS 3 DISCUSSION It was demonstrated previously with purified diets that the phosphorus requirement of growing chickens decreased with age. The first three experiments described here were designed to ascertain if this was also true in the case of growing chickens fed practical diets. The requirement for the three week old chicken fed a practical diet was at least 0.73 percent total phosphorus. The requirement decreased to 0.60 percent for the period between four and ten weeks of age. The requirement decreased to not more than 0.44 percent for the period between ten and forty-two weeks of age. The fourth experiment was initiated to test the practical application of these results. The requirement of the cockerels for phosphorus to eight weeks was at least 0.7 percent. However, the growth rate of the pullets was optimum when they received 0.60 percent phosphorus to eight weeks. The basal rations, which supplied 0.40 percent of phosphorus at the beginning of the growing period and decreased to 0.3 percent later, did not allow maximum growth until late in the growing period but contained sufficient phosphorus for normal egg production. It seemed that even though the level of phosphorus fed to the growing chicken was suboptimal for maximum growth, no deleterious effects were manifested in date of first egg or egg production. Three further experiments were conducted in which a diet containing no more than 0.4 percent phosphorus maintained normal production and hatchability. The data demonstrate that the phosphorus requirement of chickens decreases with age and that phosphorus feeding should be regulated in accordance with the age of the chicken. In experiments 3, 4,, 6 and 7 no deleterious effect of rations unsupplemented with inorganic phosphorus was observed when egg production and hatchability were the criteria. Therefore it is conceivable that, with the rations commonly supplied to laying hens, no phosphorus supplementation of the basal ration would be needed. SUMMARY Experiments were conducted with diets composed of natural ingredients and containing some phytin phosphorus to determine the phosphorus requirements of the chicken at different stages of growth. A series of three experiments demonstrated that phosphorus requirement of growing chickens decreased with age. The levels of phosphorus required were at least 0.73 percent to 3 weeks, 0.60 percent from 4 to 10 weeks and not more than 0.4 percent from 10 weeks to sexual maturity. In the fourth experiment, which was a practical application of the above concept, the phosphorus requirement for the 0 to 8 week old cockerels was 0.7 percent while the requirement of the pullets was 0.60 percent. The requirement of the pullets decreased to 0.0 percent from 8 weeks until sexual maturity. However, the basal ration containing 0.3 percent phosphorus, nearly all from plant sources, although deficient for maximum growth, contained sufficient phosphorus for normal date of first egg and egg production. Further, the pullets fed the basal ration achieved normal growth at least by 4 weeks. The data from three experiments conducted with laying pullets indicated that no more than the phosphorus contained in the basal ration, 0.43 percent, was needed to maintain egg production at a normal level. The requirement for phosphorus by the laying pullet could not be determined as the practical rations em-

8 4 NEWS AND NOTES ployed were not sufficiently low in phosphorus to demonstrate a deficiency. REFERENCES Association of Official Agricultural Chemists, 194. Official and tentative methods of analysis: Branion, H. D., Minerals in poultry nutrition. Sci. Agr. 18: Carver, J. S., J. R. Evans and J. McGinnis, Calcium, phosphorus and vitamin D interrelationships in the nutrition of the growing chick. Poultry Sci. : Couch, J. R., G. S. Fraps and R. M. Sherwood, Vitamin D requirements of growing chicks as affected by the calcium content of the ration. Poultry Sci. 16: Fiske, C. H., and Y. Subbarow, 19. The colorimetric determination of phosphorus. J. Biol. Chem. 66: 37-^00. Gillis, M. B., L. C. Norris and G. F. Heuser, The effect of phytin on the phosphorus requirement of the chick. Poultry Sci. 8: Heuser, G. F., L. C. Norris, J. McGinnis and M. L. Scott, Further evidence of the need for supplementing soybean meal chick rations with phosphorus. Poultry Sci. : Lowe, J. T., H. Steenbock and C. H. Krieger, the Poultry Science Association. He is a Past- President and Fellow of the Poultry Science Association. Jull Hall contains the offices and Bacteriology, Chemistry and Physiology Laboratories. It is also the official location of the Poultry Industry Hall of Fame, sponsored by the American Poultry Historical Society. At the dedication ceremonies Dr. T. B. Symons was the Master of Ceremonies. The dedication of Jull Hall and its acceptance by the Board of Regents was made by Judge W. P. Cole, Jr., Chairman of the Board of Regents. Dr. J. M. Gwin, Director of Extension gave an appreciation of "Morley A. JullThe Man Behind The Name." The plaque, naming the building, was presented by H. P. Klahold, President of the Maryland State Poultry Council, and was unveiled by Mrs. W. W. Hopkins, Treasurer of the Maryland State Poultry Council. NEWS AND NOTES {Continued from page 38) Cereals and rickets. IX. The availability of phytin-p to the chick. Poultry Sci. 18: McGinnis, J., L. C. Norris and G. F. Heuser, Poor utilization of phosphorus in cereals and legumes by chicks for bone development. Poultry Sci. 3: National Research Council, 190. Recommended nutrient allowances for domestic animals. Number 1. Recommended nutrient allowances for poultry. Nowotarski, J. S., and H. R. Bird, Dietary calcium and phosphorus levels and vitamin D requirement of the chick. Poultry Sci. : O'Rourke, W. F., P. H. Phillips and W. W. Cravens, 19. The phosphorus requirements of growing chickens as related to age. Poultry Sci. 31: O'Rourke, W. F., H. R. Bird, P. H. Phillips and W. W. Cravens, 194. The effect of low phosphorus rations on egg production and hatchability. Poultry Sci. 33: Singsen, E. P., and H. H. Mitchell, Soybean meal chick rations need no inorganic phosphorus supplements. Poultry Sci. 3: Sloan, H. J., and H. S. Wilgus, Jr., Heart probea method for obtaining blood samples from chickens. Poultry Sci. 10: Snedecor, G. W., Statistical Analysis. The Iowa State College Press. HALL OF FAME On September 1, 194, Jull Hall at the University of Maryland, College Park was officially dedicated and accepted as the official location of the Poultry Industry Hall of Fame, sponsored by the American Poultry Historical Society. The presentation of Jull Hall as the official location was made by Dr. G. M. Cairns, Dean of the College of Agriculture, and H. H. Alp, President of the American Poultry Historical Society, accepted the Hall. T. Leavitt, First Vice-President of the Society unveiled the plaque, and Dr. W. H. Elkins, President of the University of Maryland, accepted the Hall of Fame on behalf of the University. At the banquet held that evening, H. H. Alp presented five portraits to the Hall of Fame. In order to qualify for recognition in the Hall of Fame, an individual must be sponsored by a national or regional poultry association and must be acceptable to {Continued on page 90)