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The Effect of the Quantity and Quality of Light on the Thyroid Activity of the Baby Chick1
T h e Effect of the Quantity and Quality of Light on the Thyroid Activity of the Baby Chick1 MARY ELIZABETH KLEINPETER AND JOHN P. MIXNER 2 Department of Zoology, Louisiana State University, Baton Rouge (Received for publication March 26, 1947)
ARIOUS investigations have indicated the cyclic nature of thyroid gland activity, increased activity being associated with winter and decreased activity with summer. Levine and Remington (1933) have suggested that the variable nature of thyroid activity might.be due to a change in one or more of three environmental factors, namely, iodine content of food, temperature and light. Kligler et al. (1945) after observing in rats that the effects of changes in relative humidity were similar to those following thyroid stimulation suggested that changes in the relative humidity may cause increased thyroid activity. Many observations have been made to the effect that temperature is an important factor in relation to thyroid activity. Direct evidence of this has recently been reported by Dempsey and Astwood (1943) who found that the thyroid glands of rats secreted 1-thyroxine at the rate of 9.5 micrograms per day when kept at a temperature of 1°C, but at a rate of only 1.7 micrograms per day when kept at a temperature of 35°C. Reineke and Turner (1945) have noted a seasonal rhythm in the thyroid hormone secretion of chicks even when the enivronmental temperature was relatively con1
Data taken from Master's degree thesis submitted by the senior author in the Department of Zoology, Louisiana State University. 2 Present address: Dairy Research Station, Sussex, N. J.
stant suggesting the influence of light or other factors. Stein and Carpenter (1943), using the height of the follicular epithelium and the number of follicles as the criteria of thyroid activity, found that light stimulated increased activity of the thyroid of the salamander, Triturus viridescens. Turner and Benedict (1932) found evidence that in the chick the absence of ultraviolet light for 55 to 105 days resulted in marked thyroid hypertrophy and colloid loss: Burger (1938) found that male starlings which had been experimentally sexually stimulated with light also showed hyperplasia of the thyroid. These reports suggest that light may also be an important environmental factor which influences the activity of the thyroid gland. The following experiments are for the purpose of further investigating the influence of both the quantity and quality of light on the level of thyroid hormone secretion of the baby chick. Materials and Methods: Thyroxine secretion rates were determined for male baby chicks3 from a cross between New Hampshire males and Barred Plymouth Rock females which were kept under the following light conditions: group 1, exposed to white fluorescent light from 7:00 a.m. until 7:00 p.m. each day and 3 Experimental chicks were supplied through the cooperation of Mr. B. A. Tower and Dr. C. W. Upp, Poultry Research Department, Louisiana State University.
494
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
V
QUANTITY AND QUALITY OF LIGHT AND THYROID ACTIVITY
Thus for the purpose of assay, each light group was divided into the following subgroups with treatments as follows:
1 2 3 4 5
controls, no thiouracil, no thyroxine 0 . 1 % thiouracil in feed—no thyroxine 0 . 1 % thiouracil in f e e d ^ l 7 d,l-thyroxine daily 0 . 1 % thiouracil in feed—27 d,l-thyroxine daily 0 . 1 % thiouracil in feed—2.S7 d,l-thyroxine daily
The crystalline d,l-thyroxine 5 used was dissolved in a basic aqueous solution such that 0.1 ml. contained the daily dosage for subcutaneous injection. Light. tight compartments measuring approximately 3 ' X 2 ' X l i ' were used to house the chicks. Two 40 watt daylight fluorescent lights were used as a light source in each compartment. These lights were suspended from the top of each compartment at a distance of approximately 12" from the floor. Red and blue cellophane papers were wrapped around the fluorescent light tubes as light filters to produce the colored lights. The room in which the chicks were kept had a northern exposure, was steam heated and the temperature was thermostatically controlled to between 90° and 96°F. during the first week and to between 84° and 90°F. during the second week of each experiment. All experiments were conducted between January 26 and May 4. Thus these experiments extended over a 3 months' period. Since all subgroup treatments of the five light groups could not be conducted simultaneously, comparable subgroup treatments of the five light groups were conducted simultaneously. This experimental procedure would eliminate the influence of any seasonal effect as such upon the final comparisons of influence of light intensities. Chicks were killed with
4
Acknowledgment is due to Dr. L. H. Flint, Department of Botany, for making available the fluorescent lights used in these experiments and for his advice and counsel in connection with the study.
6 The d,l-thyroxine was supplied through the courtesy of Dr. Erwin Schwenk, Schering Corporation, Bloomfield, N. J.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
kept in complete darkness the remaining twelve hours; group 2, ordinary day light conditions present in laboratory; groups 3, 4, and 5, exposed to 24 hours of blue, red and white fluorescent lights4 daily, respectively. Baby chicks were started on the assay for thyroxine secretion rates at one day of age and were continued on assay for 14 days. The determination of the rates of thyroxine secretion of these chicks is according to a method first used by Dempsey and Astwood (1943) with rats and by Mixner, Reineke and Turner (1944), Schultze and Turner (1945) and Mixner and Upp (1947) with chickens. This method involves the administration of a chemical, thiouracil, in the feed of groups of chicks at a level of 0.1 percent. The thiouracil completely inhibits the production of the thyroid hormone by the thyroid glands which in turn allows an increased secretion of thyrotrophin by the anterior pituitary, causing thyroid enlargement. This enlargement may be prevented by simultaneous injections of thyroxine, the degree of inhibition of enlargement being roughly proportional to the thyroxine dosage. That amount of injected thyroxine required to establish a normal thyroxine-thyrotorphin balance and hence cause the thyroid weights of the thiouracil treated chicks to be equal to that of control chicks is taken to be a measure of the amount of thyroxine being secreted by the birds of a particular group of chicks under the conditions of the experiment.
495
496
MARY ELIZABETH KLEINPETER AND JOHN P. MIXNER
Experimental Results A comparison of the thyroxine secretion rates per bird per day of group V—24 hours white fluorescent light—with those of birds of group I—12 hours white fluorescent light and 12 hours darkness—will perhaps give the best estimate of the influence of the intensity of light stimulation upon thyroid activity (Table 1). It will be noted that birds of group V have an approximately 20 percent greater rate of thyroxine secretion per bird per day than do birds of group I. It will be noted also that the thyroxine secretion rate of birds of group II—natural light conditions, ap6
The thiouracil used in these experiments was kindly supplied by Dr. Stanton M. Hardy, Lederle Laboratories, Inc., Pearl River, New York.
proximates that of birds of group I, 12 hours white fluorescent light—12 hours darkness. Thus it would appear from these comparisons that the total intensity of light stimulation has only a moderate effect on the rate of thyroxine section per bird per day. The effect in no way compares to the magnitude of effect which temperature may exert on thyroid activity in rats as reported by Dempsey and Astwood (1943). A comparison of the thyroid secretion rates of birds of light groups III, IV and V for 24 hours blue, red and white fluorescent lights respectively, gives an indication as to the effect of the quality of light stimulation upon thyroidal activity. Relatively minor differences are exhibited here, the advantage being with birds of the 24 hour white fluorescent light group. The birds of these groups in the main responded in a manner which would suggest that any differences in activity are due to light intensity differences rather than quality of light differences. It is interesting to note that the birds of the 24 hour light groups, white, red and blue, are superior to birds of the 12 hour light group or to birds of the natural light group in their thyroidal activity. The indications are then that the effect of increased light exposures upon thyroid activity is much less stimulatory than is the effect of lowered temperature. This is concluded by comparing our results with those of Dempsey and Astwood (1943) who obtained a 458.8 percent increase in the level of thyroxine secretion of rats upon,lowering the temperature from 35°C. to 1°C. Compared to this the 20.8 percent increase in thyroidal activity secured in the birds of the 24 hour white fluorescent light group over birds in the 12 hour white fluorescent light—12 hours dark group seems relatively small. Although Reineke and Turner (1945)
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
ether, body weights were recorded, thyroid glands were dissected out and weighed on a chainomatic balance to the nearest 0.1 mg. The method of plotting the data for the various sub-group treatments in order to secure an estimation of the thyroxine secretion level is the same as that used by Mixner, Reineke and Turner (.1944), Schultze and Turner (1945) and Mixner and Upp (1947). In this connection it should be noted that thyroxine is actually secreted by the thyroid gland in the 1form which is twice as active as the d e form and hence to secure the weight of 1-thyroxine equivalent, the weight of the d,l-thyroxine estimated must be halved (Reineke and Turner, 1945). The feed used was a standard commercial chick growing mash. Thiouracil6 was administered as a part of this mash ration at a level of 0.1 percent. This amount of thiouracil was found by Mixner Reineke and Turner (1944) to cause maximum thyroid enlargement in baby chicks and thus indicates total inhibition of the thyroid secretion.
Q U A N T I T Y AND QUALITY OF L I G H T AND T H Y R O I D ACTIVITY
497
TABLE 1. The intensity and quality of light as factors influencing thyroid activity of baby chicks Average thyroxine secretion rates Subgroup treatment Thiouracil in feed,
%
d,l-thyroxine 7
none none 0.1 none 0.1 1.0 G.l 2.0 0.1 2.5 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 2.5 0.1 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 All sub groups
Average Body wt. 2 weeks gms.
mg
-
I>er 100 gm body wt.
Per bird MUM-
S ?y dail
Pe rcent
,
=
n riA-iTO
level
Group I—12 hours white fluorescent light—12 hours darkness 26 95.8 5.9*1 31 86.3 40.9 15 94.5 18.8 1.97 — 15 88.4 5.6 12 89.5 3.4 . 99 90.9 Group I I —Natural light conditions 26 99.6 5.7*1 29 94.5 42.9 18 106.1 18.4 2.05 4.6 13 97.6 6.3 14 97.3 4.2 , 100 99.0 Group III—.24 hours blue fluorescent light 29 106.3 5.6*1 31 93.2 41.7 16 93.0 22.7 2.18 10.7 14 91.5 7.3 t 16 95.1 4.2 . 106 95.8 Group I V --24 hours red fluorescent light 27 109.3 6.3*1 29 90.2 46.9 15 97.9 33.3 2.30 16.7 16 98.1 8.1 16 92.3 4.8 103 97.6 Group V—24 hours white fluorescent light 30 113.5 6.5*1 32 95.4 49.5 18 101.1 30.0 2.38 20.8 16 100.3 10.6 15 98.8 4.7 , 111 101.8
Milligrams daily
Percent above lowest level
2.17
4.8
2.07
—
2.28
10.1
2.36
14.0
2.34
13.2
* The average of these five figures (6.0 mgs.) was used as the normal thyroid weight in all five light groups in estimating thyroxine secretion rates by plotting technic.
have noted decreased thyroid activity in baby chicks in those parts of the year when the intensity of light stimulation is greatest, these experiments would indicate that the greater light intensity per se is not a factor contributing to this inhibition. SUMMARY The influence of both the quantity and quality of light upon the thyroid activity of male baby chicks of a New Hampshire
male X Barred Plymouth Rock female cross during the first two weeks after hatching was determined using the following light conditions over a 14-day period: Group 1.—12 hours white fluorescent light and 12 hours darkness. Group 2.—Natural light conditions of the laboratory. Group 3.—24 hours blue fluorescent light.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 ' All subgroups
No. of chicks
Thyrou 1 wt. per 100 gm body wt
498
NEWS AND NOTES
Group 4.—24 hours red fluorescent light. Group 5.—24 hours white fluorescent light. The thyroxine secretion rates in terms of d,l-thyroxine per bird per day under the above light conditions were as follows:
1 2 3 4 5
Per cent increase over lowest — 4.6 10.7 16.7 20.8
It is suggested that any influence of the quality of light in these experiments upon thyroid activity can be explained adequately on the basis of the quantity of light involved in each case. REFERENCES
Burger, J. W., 1938. Cyclic Changes in the Thyroid and Adrenal Cortex of the Male Starling, Sturnus vulgaris, and Their Relation to the Sexual Cycle. Am. Nat. 72:562-570. Dernpsey, E. W. and E. B. Astwood, 1943. Deter-
News and Notes Dr. Lawrence Morris, formerly in charge cf Poultry Husbandry at the University of Wyoming, has accepted the position of Extension Poultryman at Utah State College. M. H. Meshew has transferred from Extension Poultryman to Poultryman in charge of teaching and research in the Animal Production Department, University of Wyoming. C. A. Roberts, recently in the Extension Division at Mississippi State College, has returned to Oklahoma A. & M. College to take charge of teaching the elementary
and the judging classes in the Department of Poultry Husbandry. The World's Poultry Congress Pilgrims, meeting in Cleveland, Ohio, July 22, elected: President, Dr. O. B. Kent; Vice President, Dr. Morley A. Jull; and Secretary, S. L. Althouse. Ninety-four pilgrims were present to hear the report of W. D. Terhmolen and a vivid portrayal of life in Denmark by Erik Jensen, commercial attache, Danish Embassy, Washington, D. C. The Congress Tour Committee is headed by Leon Todd, 11 West State Street, Trenton, New Jersey.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
Group Group Group Group Group
Micrograms d,l-thyroxine bird per day 1.97 2.05 2.18 2.30 2.38
mination of the Rate of Thyroid Hormone Secretion at Various Environmental Temperatures. Endocrinology 34: 509-518. Kligler, I. J., K. Guggenheim and I. Schwartz, 1945. Adaptation to Changes in Environmental Humidity at Constant Temperatures. Proc. Soc. Exp. Biol. & Med. 58: 286-289. Levine, H. and R. F. Remington, 1933. Is Goiter Due to an Iodine Deficiency per se? / . Chem. Educ. 10: 649-659. Mixner, J. P., E. P. Reineke, and C. W. Turner, 1944. The Effect of Thiouracil and Thiourea on the Thyroid Gland of the Chick. Endocrinology 34: 168-174. Mixner, J. P., and C. W. Upp. 1947. Increased Rate of Thyroxine Secretion by Hybrid Chicks, a Factor in Heterosis. Poultry Sci. 26: 389-395. Reineke, E. P. and C. W. Turner, 1945. The Relative Thyroidal Potency of 1-and d, 1-thyroxine. Endocrinology 36:200-206. Reineke, E. P. and C. W. Turner, 1945. Seasonal Rhythm in the Thyroid Hormone Secretion of the Chick. Poultry Sci. 24: 499-504. Schultze, A. B. and C. W. Turner, 1945. The Determination of the Rate of Thyroxine Secretion by Certain Domestic Animals. Mo. Agr. Exp. Sta. Res. Bui. 392. Stein, K. and E. Carpenter, 194/. The Effect of Increased and Decreased Light on the Thyroid Gland of Triturus viridescens. J. Morph. 72: 491515. Turner, K. B. and E. M. Benedict, 1932. Thyroid Hyperplasia Produced in Chickens by Ultraviolet Light Deficiency. / . Clinical Invest. 11:761-774.
ARIOUS investigations have indicated the cyclic nature of thyroid gland activity, increased activity being associated with winter and decreased activity with summer. Levine and Remington (1933) have suggested that the variable nature of thyroid activity might.be due to a change in one or more of three environmental factors, namely, iodine content of food, temperature and light. Kligler et al. (1945) after observing in rats that the effects of changes in relative humidity were similar to those following thyroid stimulation suggested that changes in the relative humidity may cause increased thyroid activity. Many observations have been made to the effect that temperature is an important factor in relation to thyroid activity. Direct evidence of this has recently been reported by Dempsey and Astwood (1943) who found that the thyroid glands of rats secreted 1-thyroxine at the rate of 9.5 micrograms per day when kept at a temperature of 1°C, but at a rate of only 1.7 micrograms per day when kept at a temperature of 35°C. Reineke and Turner (1945) have noted a seasonal rhythm in the thyroid hormone secretion of chicks even when the enivronmental temperature was relatively con1
Data taken from Master's degree thesis submitted by the senior author in the Department of Zoology, Louisiana State University. 2 Present address: Dairy Research Station, Sussex, N. J.
stant suggesting the influence of light or other factors. Stein and Carpenter (1943), using the height of the follicular epithelium and the number of follicles as the criteria of thyroid activity, found that light stimulated increased activity of the thyroid of the salamander, Triturus viridescens. Turner and Benedict (1932) found evidence that in the chick the absence of ultraviolet light for 55 to 105 days resulted in marked thyroid hypertrophy and colloid loss: Burger (1938) found that male starlings which had been experimentally sexually stimulated with light also showed hyperplasia of the thyroid. These reports suggest that light may also be an important environmental factor which influences the activity of the thyroid gland. The following experiments are for the purpose of further investigating the influence of both the quantity and quality of light on the level of thyroid hormone secretion of the baby chick. Materials and Methods: Thyroxine secretion rates were determined for male baby chicks3 from a cross between New Hampshire males and Barred Plymouth Rock females which were kept under the following light conditions: group 1, exposed to white fluorescent light from 7:00 a.m. until 7:00 p.m. each day and 3 Experimental chicks were supplied through the cooperation of Mr. B. A. Tower and Dr. C. W. Upp, Poultry Research Department, Louisiana State University.
494
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
V
QUANTITY AND QUALITY OF LIGHT AND THYROID ACTIVITY
Thus for the purpose of assay, each light group was divided into the following subgroups with treatments as follows:
1 2 3 4 5
controls, no thiouracil, no thyroxine 0 . 1 % thiouracil in feed—no thyroxine 0 . 1 % thiouracil in f e e d ^ l 7 d,l-thyroxine daily 0 . 1 % thiouracil in feed—27 d,l-thyroxine daily 0 . 1 % thiouracil in feed—2.S7 d,l-thyroxine daily
The crystalline d,l-thyroxine 5 used was dissolved in a basic aqueous solution such that 0.1 ml. contained the daily dosage for subcutaneous injection. Light. tight compartments measuring approximately 3 ' X 2 ' X l i ' were used to house the chicks. Two 40 watt daylight fluorescent lights were used as a light source in each compartment. These lights were suspended from the top of each compartment at a distance of approximately 12" from the floor. Red and blue cellophane papers were wrapped around the fluorescent light tubes as light filters to produce the colored lights. The room in which the chicks were kept had a northern exposure, was steam heated and the temperature was thermostatically controlled to between 90° and 96°F. during the first week and to between 84° and 90°F. during the second week of each experiment. All experiments were conducted between January 26 and May 4. Thus these experiments extended over a 3 months' period. Since all subgroup treatments of the five light groups could not be conducted simultaneously, comparable subgroup treatments of the five light groups were conducted simultaneously. This experimental procedure would eliminate the influence of any seasonal effect as such upon the final comparisons of influence of light intensities. Chicks were killed with
4
Acknowledgment is due to Dr. L. H. Flint, Department of Botany, for making available the fluorescent lights used in these experiments and for his advice and counsel in connection with the study.
6 The d,l-thyroxine was supplied through the courtesy of Dr. Erwin Schwenk, Schering Corporation, Bloomfield, N. J.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
kept in complete darkness the remaining twelve hours; group 2, ordinary day light conditions present in laboratory; groups 3, 4, and 5, exposed to 24 hours of blue, red and white fluorescent lights4 daily, respectively. Baby chicks were started on the assay for thyroxine secretion rates at one day of age and were continued on assay for 14 days. The determination of the rates of thyroxine secretion of these chicks is according to a method first used by Dempsey and Astwood (1943) with rats and by Mixner, Reineke and Turner (1944), Schultze and Turner (1945) and Mixner and Upp (1947) with chickens. This method involves the administration of a chemical, thiouracil, in the feed of groups of chicks at a level of 0.1 percent. The thiouracil completely inhibits the production of the thyroid hormone by the thyroid glands which in turn allows an increased secretion of thyrotrophin by the anterior pituitary, causing thyroid enlargement. This enlargement may be prevented by simultaneous injections of thyroxine, the degree of inhibition of enlargement being roughly proportional to the thyroxine dosage. That amount of injected thyroxine required to establish a normal thyroxine-thyrotorphin balance and hence cause the thyroid weights of the thiouracil treated chicks to be equal to that of control chicks is taken to be a measure of the amount of thyroxine being secreted by the birds of a particular group of chicks under the conditions of the experiment.
495
496
MARY ELIZABETH KLEINPETER AND JOHN P. MIXNER
Experimental Results A comparison of the thyroxine secretion rates per bird per day of group V—24 hours white fluorescent light—with those of birds of group I—12 hours white fluorescent light and 12 hours darkness—will perhaps give the best estimate of the influence of the intensity of light stimulation upon thyroid activity (Table 1). It will be noted that birds of group V have an approximately 20 percent greater rate of thyroxine secretion per bird per day than do birds of group I. It will be noted also that the thyroxine secretion rate of birds of group II—natural light conditions, ap6
The thiouracil used in these experiments was kindly supplied by Dr. Stanton M. Hardy, Lederle Laboratories, Inc., Pearl River, New York.
proximates that of birds of group I, 12 hours white fluorescent light—12 hours darkness. Thus it would appear from these comparisons that the total intensity of light stimulation has only a moderate effect on the rate of thyroxine section per bird per day. The effect in no way compares to the magnitude of effect which temperature may exert on thyroid activity in rats as reported by Dempsey and Astwood (1943). A comparison of the thyroid secretion rates of birds of light groups III, IV and V for 24 hours blue, red and white fluorescent lights respectively, gives an indication as to the effect of the quality of light stimulation upon thyroidal activity. Relatively minor differences are exhibited here, the advantage being with birds of the 24 hour white fluorescent light group. The birds of these groups in the main responded in a manner which would suggest that any differences in activity are due to light intensity differences rather than quality of light differences. It is interesting to note that the birds of the 24 hour light groups, white, red and blue, are superior to birds of the 12 hour light group or to birds of the natural light group in their thyroidal activity. The indications are then that the effect of increased light exposures upon thyroid activity is much less stimulatory than is the effect of lowered temperature. This is concluded by comparing our results with those of Dempsey and Astwood (1943) who obtained a 458.8 percent increase in the level of thyroxine secretion of rats upon,lowering the temperature from 35°C. to 1°C. Compared to this the 20.8 percent increase in thyroidal activity secured in the birds of the 24 hour white fluorescent light group over birds in the 12 hour white fluorescent light—12 hours dark group seems relatively small. Although Reineke and Turner (1945)
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
ether, body weights were recorded, thyroid glands were dissected out and weighed on a chainomatic balance to the nearest 0.1 mg. The method of plotting the data for the various sub-group treatments in order to secure an estimation of the thyroxine secretion level is the same as that used by Mixner, Reineke and Turner (.1944), Schultze and Turner (1945) and Mixner and Upp (1947). In this connection it should be noted that thyroxine is actually secreted by the thyroid gland in the 1form which is twice as active as the d e form and hence to secure the weight of 1-thyroxine equivalent, the weight of the d,l-thyroxine estimated must be halved (Reineke and Turner, 1945). The feed used was a standard commercial chick growing mash. Thiouracil6 was administered as a part of this mash ration at a level of 0.1 percent. This amount of thiouracil was found by Mixner Reineke and Turner (1944) to cause maximum thyroid enlargement in baby chicks and thus indicates total inhibition of the thyroid secretion.
Q U A N T I T Y AND QUALITY OF L I G H T AND T H Y R O I D ACTIVITY
497
TABLE 1. The intensity and quality of light as factors influencing thyroid activity of baby chicks Average thyroxine secretion rates Subgroup treatment Thiouracil in feed,
%
d,l-thyroxine 7
none none 0.1 none 0.1 1.0 G.l 2.0 0.1 2.5 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 2.5 0.1 All subgroups none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 All sub groups
Average Body wt. 2 weeks gms.
mg
-
I>er 100 gm body wt.
Per bird MUM-
S ?y dail
Pe rcent
,
=
n riA-iTO
level
Group I—12 hours white fluorescent light—12 hours darkness 26 95.8 5.9*1 31 86.3 40.9 15 94.5 18.8 1.97 — 15 88.4 5.6 12 89.5 3.4 . 99 90.9 Group I I —Natural light conditions 26 99.6 5.7*1 29 94.5 42.9 18 106.1 18.4 2.05 4.6 13 97.6 6.3 14 97.3 4.2 , 100 99.0 Group III—.24 hours blue fluorescent light 29 106.3 5.6*1 31 93.2 41.7 16 93.0 22.7 2.18 10.7 14 91.5 7.3 t 16 95.1 4.2 . 106 95.8 Group I V --24 hours red fluorescent light 27 109.3 6.3*1 29 90.2 46.9 15 97.9 33.3 2.30 16.7 16 98.1 8.1 16 92.3 4.8 103 97.6 Group V—24 hours white fluorescent light 30 113.5 6.5*1 32 95.4 49.5 18 101.1 30.0 2.38 20.8 16 100.3 10.6 15 98.8 4.7 , 111 101.8
Milligrams daily
Percent above lowest level
2.17
4.8
2.07
—
2.28
10.1
2.36
14.0
2.34
13.2
* The average of these five figures (6.0 mgs.) was used as the normal thyroid weight in all five light groups in estimating thyroxine secretion rates by plotting technic.
have noted decreased thyroid activity in baby chicks in those parts of the year when the intensity of light stimulation is greatest, these experiments would indicate that the greater light intensity per se is not a factor contributing to this inhibition. SUMMARY The influence of both the quantity and quality of light upon the thyroid activity of male baby chicks of a New Hampshire
male X Barred Plymouth Rock female cross during the first two weeks after hatching was determined using the following light conditions over a 14-day period: Group 1.—12 hours white fluorescent light and 12 hours darkness. Group 2.—Natural light conditions of the laboratory. Group 3.—24 hours blue fluorescent light.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
none none 0.1 none 0.1 1.0 0.1 2.0 0.1 2.5 ' All subgroups
No. of chicks
Thyrou 1 wt. per 100 gm body wt
498
NEWS AND NOTES
Group 4.—24 hours red fluorescent light. Group 5.—24 hours white fluorescent light. The thyroxine secretion rates in terms of d,l-thyroxine per bird per day under the above light conditions were as follows:
1 2 3 4 5
Per cent increase over lowest — 4.6 10.7 16.7 20.8
It is suggested that any influence of the quality of light in these experiments upon thyroid activity can be explained adequately on the basis of the quantity of light involved in each case. REFERENCES
Burger, J. W., 1938. Cyclic Changes in the Thyroid and Adrenal Cortex of the Male Starling, Sturnus vulgaris, and Their Relation to the Sexual Cycle. Am. Nat. 72:562-570. Dernpsey, E. W. and E. B. Astwood, 1943. Deter-
News and Notes Dr. Lawrence Morris, formerly in charge cf Poultry Husbandry at the University of Wyoming, has accepted the position of Extension Poultryman at Utah State College. M. H. Meshew has transferred from Extension Poultryman to Poultryman in charge of teaching and research in the Animal Production Department, University of Wyoming. C. A. Roberts, recently in the Extension Division at Mississippi State College, has returned to Oklahoma A. & M. College to take charge of teaching the elementary
and the judging classes in the Department of Poultry Husbandry. The World's Poultry Congress Pilgrims, meeting in Cleveland, Ohio, July 22, elected: President, Dr. O. B. Kent; Vice President, Dr. Morley A. Jull; and Secretary, S. L. Althouse. Ninety-four pilgrims were present to hear the report of W. D. Terhmolen and a vivid portrayal of life in Denmark by Erik Jensen, commercial attache, Danish Embassy, Washington, D. C. The Congress Tour Committee is headed by Leon Todd, 11 West State Street, Trenton, New Jersey.
Downloaded from http://ps.oxfordjournals.org/ at Simon Fraser University on June 5, 2015
Group Group Group Group Group
Micrograms d,l-thyroxine bird per day 1.97 2.05 2.18 2.30 2.38
mination of the Rate of Thyroid Hormone Secretion at Various Environmental Temperatures. Endocrinology 34: 509-518. Kligler, I. J., K. Guggenheim and I. Schwartz, 1945. Adaptation to Changes in Environmental Humidity at Constant Temperatures. Proc. Soc. Exp. Biol. & Med. 58: 286-289. Levine, H. and R. F. Remington, 1933. Is Goiter Due to an Iodine Deficiency per se? / . Chem. Educ. 10: 649-659. Mixner, J. P., E. P. Reineke, and C. W. Turner, 1944. The Effect of Thiouracil and Thiourea on the Thyroid Gland of the Chick. Endocrinology 34: 168-174. Mixner, J. P., and C. W. Upp. 1947. Increased Rate of Thyroxine Secretion by Hybrid Chicks, a Factor in Heterosis. Poultry Sci. 26: 389-395. Reineke, E. P. and C. W. Turner, 1945. The Relative Thyroidal Potency of 1-and d, 1-thyroxine. Endocrinology 36:200-206. Reineke, E. P. and C. W. Turner, 1945. Seasonal Rhythm in the Thyroid Hormone Secretion of the Chick. Poultry Sci. 24: 499-504. Schultze, A. B. and C. W. Turner, 1945. The Determination of the Rate of Thyroxine Secretion by Certain Domestic Animals. Mo. Agr. Exp. Sta. Res. Bui. 392. Stein, K. and E. Carpenter, 194/. The Effect of Increased and Decreased Light on the Thyroid Gland of Triturus viridescens. J. Morph. 72: 491515. Turner, K. B. and E. M. Benedict, 1932. Thyroid Hyperplasia Produced in Chickens by Ultraviolet Light Deficiency. / . Clinical Invest. 11:761-774.