The Relation of the Preen Gland to Rickets in the Domestic Fowl*

T h e Relation of the Preen Gland to Rickets in the Domestic Fowl* H. R. K N O W L E S , E. B. HART AND J. G. H A L P I N

University of Wisconsin, Madison (Received for Publication October 11, 1933)

S Hou (1928) has pointed out in his pin (1927), while studying the site of ac- review of the literature, the preen tivation by irradiation, showed that when gland in birds has long been a subject of the heads only, and again when the feet discussion; but, as yet, no specific indis- and legs of birds were irradiated, these birds pensable function has been assigned to it. laid more eggs than those receiving irradiaHou, on the basis of his own work, con- tion on the body (head and legs protected); cluded that the removal of the preen gland and, moreover, the eggs of these hens from adult birds caused a disturbance of the hatched better, showing under the condifeather growth and an impairment of gen- tions of this experiment that these eggs had eral health, while in young birds its removal higher stores of vitamin D (see Table 1). caused rickets, in spite of normal feeding Since the birds in the "body only" group and sunshine treatment. One of the func- had not had their preen glands removed tions of this gland, as proposed by Hou, there must have been some of the secretion is the production of a secretion which the of the preen gland on the feathers, which bird, during the act of preening, rubs over according to Hou's theory, should then its feathers. Activation of some of the con- have been activated by the irradiation and stituents of this material, during its expo- have afforded protection, but failed to do sure to the sun, leads to the formation of so. In a later paper Hou (1931) showed vitamin D. The vitamin is then taken in by that rachitic chicks, with preen glands rethe bird, via the mouth, at a subsequent moved, exhibited good healing when the legs preening; or, there is the possibility that were irradiated. it may be absorbed through the skin, or It was with the above facts in mind that even via the shaft of the feather. the following experiments were undertaken, Since the growing chick and the laying in order to test further whether there was hen require relatively large amounts of vita- any relation between the secretion of the min D, this theory seemed to have some preen gland and the metabolism of vitajustification, especially when it is borne in min D. mind that their bodies are covered with a EXPERIMENTAL PROCEDURE dense layer of feathers, and their legs have Experiment 1.—In the first trial twentya cornified epidermis, both of which might seven three-day-old White Leghorn chicks act as insulators to the shorter waves of were divided into four groups and given the light. However, there still remained certain following treatment: experimental facts which were not in acGroup I—Six chicks. Ten minutes' irradicordance with this theory. Hart and Halation weekly for the first four weeks and * Published with the permission of the Director thereafter a daily irradiation of ten minof the Wisconsin Agricultural Experiment Station. utes.

A

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[33]

April Total March Total Feb. Total Jan. Total Dec. Total Nov. Total Oct. Total

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Whole hen Heads only Feet and legs Bodies only Bodies and feet No irradiation

Irradiation treatment

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c

SCIENCE

Group II—Six chicks. Preen glands removed on the tenth day. Ten minutes' irradiation weekly for the first four weeks, and thereafter a daily irradiation of ten minutes. Group III—Nine chicks. Preen glands removed on the tenth day. Ten minutes' irradiation weekly for the first four weeks, and thereafter no irradiation. Group IV—Six chicks. Preen glands removed on the tenth day. Ten minutes' irradiation weekly for the first four weeks, and thereafter one percent cod liver oil was added to the basal ration. The chicks were housed in separate compartments, so partitioned that at no time could the chickens of any one group come in contact with those of another. Once weekly, during the first four weeks, all the birds were irradiated, group by group, for ten minutes under a quartz mercury vapor lamp at a distance of 30 inches. After the first four weeks Groups I and II were irradiated daily for ten minutes while Groups III and IV received no irradiation. The basal ration used was made up as follows; yellow corn 59 percent, middlings 25 percent, casein 12 percent, CaC0 3 1 percent, Ca 3 (P0 4 ) 2 1 percent, NaCl 1 percent, yeast 1 percent. This ration will produce rickets in chicks unless some source of the antirachitic factor is added. When the chicks were ten days old they were operated on for the removal of the gland (previous experience having shown that an earlier age was inadvisable). The fluff on top of the tail was trimmed short and a small " T " incision made above the preen gland. The flaps of the skin were carefully dissected back and the intact gland carefully removed. The wound was allowed to heal by primary union. During the fourth week another incision was made and the area was then carefully inspected for any preen gland tissue which might have

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Chicks Eggs Chicks Eggs Chicks Eggs Chicks Eggs Chicks Eggs Chicks Eggs Chicks Eggs

Total

Chicks

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JANUARY,

1935.

VOL.

XIV,

No..

1

35

TABLE 2.—Average weight, and percentage ash of tibiae of chickens alive at the conclusion of Experiment I

No. of chicks alive at conclusion Ave. initial weight gms. Ave. weight 4 wks. gms. Ave. final weight 9 wks. gms. % ash (tibiae)

Group IV

Group I

Group I I

Group I I I

Normal plus irradiation

Preenless plus irradiation

Preenless, no irradiation

& 2

9 4

0" 3

45 250 755 45.7

40 200 580 45.0

45 175 675 45.8

9

3

4

5

5

45 200 640 46.0

40 170 290 31.2

40 150 270 34.7

45 210 730 46.1

9 0

method, while the inorganic phosphorus was determined by the method of Fiske and Subbarrow (1925). The data for the experiments aje recorded in Tables 2 and 3. DISCUSSION

By allowing the chicks to grow for a period of four weeks with only ten minutes' irradiation weekly it was hoped that the body stores of vitamin D would be greatly depleted, and that the preen glad oil present on the down would be lost when feathers developed in place of the down. That the stores of vitamin D were greatly depleted is borne out by the fact that four birds had developed crooked breastbones at this stage in the second experiment. A study of Tables 1 and 2 will show that at four weeks there was no significant difference in body weight between any of the

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regenerated. At the conclusion of the experiments all individuals were carefully examined and the data of those which showed any signs of regeneration were rejected from the final data (one from Experiment 1, and four from Experiment 2). The chicks were weighed weekly. At the conclusion of the trial the tibiae were removed, freed from the fibulae and all adhering flesh. The bones were then dried at sixty-five degrees for seven days, cracked in a press, extracted with ninetyfive percent alcohol for seventy-two hours, dried, weighed, and ashed in an electric furnace and the ash weighed. In the second trial thirty-two chickens were taken. At the conclusion of this trial individual samples of blood were also secured for the determination of serum Ca, according to Clark and Collip's (1925) modification of the Kramer and Tisdall

cf

9

Preenless plus 1% C.L.O.

TABLE 3.—Average weights, percentage ash of tibiae, serum Ca and inorganic P of blood of chickens alive at the conclusion of Experiment II

No. of chicks alive at conclusion Ave. initial weight gms. Ave. weight 4 wks. gms. Ave. final weight 10 wks. gms. Percentage ash Ca mg/100 cc. serum Inorganic P mg/100 cc. blood

Group I

Group I I

Group I I I

Group IV

Normal plus irradiation

Preenless plus irradiation

Preenless, no irradiation

Preenless plus 1% C.L.O.

c?

9

o*

9

d"

9

4 40 190

4 40 170

1 40 135

6 35 160

3 35 180

3 35 160

0 — —

9 5 40 150

650 46.1 11.8 3.5

505 45.2 12.5 3.7

650 45.0 10.9 3.5

410 46.0 11.3 3.2

330 32.5 10.2 4.0

265 31.9 8.1 *

— —. — —

570 44.7 11.1 3.7

* Insufficient blood available.

c?

36

SCIENCE

percent C.L.O.), since the individuals showed good growth and high tibial ash, and could not be distinguished from the normal ones. The average figures for the serum Ca and inorganic phosphorus do not reflect the range within the groups. In Group I the range for serum Ca was 11.4 mg. - 13.6 mg.; in Group II, 10.7 mg. - 11.6 mg.; in Group III, 12.5 mg. - 6.2 mg.; in Group IV, 10.9 - 11.7 mg. Thus, the only group which contained individuals showing low blood calcium was Group III (preenless, no irradiation). Inorganic phosphorus showed no variations in the respective groups. CONCLUSIONS

White Leghorn chicks with preen glands removed when ten days old grew as well as the controls, and developed skeletons with normal ash content. These experiments show that in the presence of a sufficient source of the antirachitic factor, either as ultra-violet irradiation or as cod liver oil, the preen gland is a dispensable organ for calcium metabolism in chickens. REFERENCES

Clark, E. P. and J. B. Collip, 1925. A study of the Tisdall method for the determination of blood serum calcium with a suggested modification. J. Biol. Chem., 63:461-464. Fiske, C. H., and Y. Subbarow, 1925. The colorimetric determination of phosphorus. J. Biol. Chem. 66:375-400. Hart, E. B., and J. G. Halpin, 1927. What part of the chicken's body is activated by light? Ann. Rpt. of the Director, Wis. Agr. Exp. Sta. Bui. 396, p. 48. Hou, H. C , 1928 Studies on the glandula uropygialis of birds. Chinese J. Physiol., 11:345-380. Hou, H. C , 1931. Relation of preen gland of birds to rickets. Chinese J. Physiol. 5:11-18.

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groups. Also no visible differences were discernible. From the fifth week on to the conclusion of the experiment great differences became noticeable. The birds in Group I (normal plus irradiation), those in Group II (preenless plus irradiation), and those in Group IV (preenless plus one percent cod liver oil) made rapid growth as compared with Group III (preenless, no irradiation). The percentage ash of the tibiae showed that whereas Groups I, II, and IV showed a high ash (42.2 to 48.7 percent) in Group III poor calcification had taken place since the ash was from 29.2 to 34.8 percent. In the second trial results similar to those obtained in the first were secured, viz., impaired growth and low tibial ash in Group III (preenless, no irradiation). Since the only known differences between Group I (normal plus irradiation) and Group II (preenless plus irradiation) was the presence of the preen gland in the former group and its absence from the latter, and since both groups grew well and showed a high tibial ash it is concluded that the presence of the preen gland was not essential for skeletal development, and that the ultra-violet light must have activated some other part of the body to have produced such good calcification. Since Group II (preenless plus irradiation) differed from Group III (preenless, no irradiation) only in that the former received irradiation, the poor growth and low tibial ash of the latter was obviously due to the absence of the antirachitic factor. Therefore it is concluded that the preen gland is not essential for the skeletal development of the chicken. This fact was also demonstrated by the conditions which prevailed in Group IV (preenless plus one

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