- Email: [email protected]
A Comparison of the Growth of Chicks Behind Window Glass and a Glass Substitute*
A COMPARISOiNi OF THE GROWTH OF CHICKS BEHIND WINDOW GLASS AND A GLASS SUBSTITUTE* WALTER F. WOOD JR. Vermont State School of Agriculture Randolph Center, Vermont
Since the discovery that certain disorders such as rickets in children, dogs, rats, etc., and leg weakness in chicks could be corrected by irradiation with light containing ultra-violet rays, a great deal of experimental work has been carried on. The practical application of the knowledge resulting from these investigations has opened up a new field of poultry production, which up to a short time ago had been a series of unsuccessful attempts to raise chicks in confinement. Following the discovery that window glass filtered out these necessary rays, attempts were made to find substitutes for glass which Avould allow these short invisible solar light waves to pass through. Quartz glass was found to allow sufficient transmission of these rays to protect rats against rickets, but the expense in manufacturing made this kind of glass prohibitive to commercial poultrymen, for such uses as equipping brooder houses with quartz glass windows to prevent leg weakness. Comparatively recenlty, certain glass substitutes have appeared on the market at reasonable prices and advertised as possessing the power of transmitting ultra-violet light. Such substitutes if found to transmit enough of the short beneficial light rays to prevent leg weakness would have a wide usefulness in poultry rearing· and egg production. MATERIALS AND METHOD
In order to obtain definite information from actual trials carried on during the season when broilers are being raised, the following test was commenced February 8, 1926 : 75 Rhode Island Red chicks (48 hours old) were divided into three groups of 25 chicks each and confined in separate laboratory pens. All three groups received a basal ration used for the production of leg Aveakness as employed by Hart Steenbock, and as* Gel-0-Glass was used in this trial for the glass substitute.
62
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
(Received for publication 7-30-26)
WINDOW GLASS VS. A GLASS SUBSTITUTE
63
0
INCIDENCE OF LEG WEAKNESS
At the start of the trial, the three lots were of approximately the same weight. In general appearance, Lot 2 seemed slightly inferior to Lots 1 and 3, indicated mostly by their activity. Lots 1 and 3 appeared to be normal, Lot 1 containing perhaps the most active chicks. All chicks grew normally until the end of the fourth .week, when one chick in Lot 1 (window glass) showed the preliminary symptoms of leg weakness. This chick (No. 25) shoAved first a stifl:'ness of the legs, a difficulty in walking and in a short time became unable to stand any length of time Avithout frequent rests by squatting on its hocks. The hock joints became swollen, showing a discoloration, and in six days the bird died. Probably death was brought on prematurely due to the lack of strength to reach the feed hoppers or drink. The next appearance of leg weakness symptoms came during the sixth week, when two chicks, also in Lot 1 (window glass), came down much more rapidly than did the first one mentioned in this group. Soon after the symptoms appeared. Chick No. 1 lost all power to Avalk, but by fluttering the Avings and kicking its legs it was able to remain near the feed. Of the other chicks,
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
sociates\ consisting of yellow corn meal 97 parts, CaCOg 2 parts, and NaCl, 1 part. Skim milk was provided ad libitum. The chicks were confined in a comfortably warm room, each pen having an improvised hover, made from a butter tub and heated with an electric lamp. Due to the lack of shavings during the first part of the trial, cut straw was used as litter, later being replaced with wood shavings. Each pen was placed behind a separate window with a south exposure, which contained about 9 square feet of glass or substitute. Lot 1 Was placed behind window glass, and fed the basal ration as a check Lot. Lot 2 was placed behind a window of about 9 square feet of Cel-0-Glass, and fed the same basal ration as lot 1. Lot 3 was placed under the same conditions as Lot 1, but 2 per cent of cod liver oil was incorporated in the mash. The chicks were weighed individually each week.
64
POULTRY
SCIENCE
DIAGNOSIS OP LEG WEAKNESS
Bones of the two chicks (Nos. 7 and 17) killed at nine weeks of age while showing the leg wekness condition, together, with the bones of three chicks from Lot 2—Cel-0-Glass—(Nos. 33, 44, and 46), and of one chick in Lot 3 (No. 63) were fixed in formalin and submitted to Dr. A. M. Pappenheimer, College of Physicians and Surgeons, Columbia University, for examination. Dr. Pappenheimer reported as follows : "Leg bones were received from Mr. Wood in formalin, transferred to Miiller's solution for varying periods, until decalcification was suiRcient to permit sectioning. "Of the six received, two (No. 7 and No. 17) showed definite abnor malities, both grossly and microscopically. Chicken No. 7: There is fusiform enlargement of the head of the tibioflbula. Microscopically, the cartilage cells are prolonged down wards towards the shaft for a considerable distance. Near the epi physis they form an orderly alignment, but this is lost as the diaphysis is approached, and the cartilage cells form irregular masses which merge V7ith the surrounding osteoid. The matrix of the cartilage ap pears to be irregularly calcified. On the whole, the calcium deposition Is fairly abundant. "The trabeculae of the spongiosa are broad, and irregularly disposed. They are, in the subchondral zone, composed wholly or in large part of uncalcifled osteoid, including plump oval or vesicular nuclei, sug gesting metaplastic cartilage cells rather than diiferentiated bone cor-
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
No. 7, was given cod liΛ^er oil as used in Lot 3, to test its powers in preventing leg weakness. The chick partially recovered, and later came down again -viath leg weakness. During the 7th week the entire window-glass pen began to show the abnormal symptoms preliminary to the condition of leg weakness . By the end of the trial all chicks in this lot had come down with varying degrees of leg weakness. Nos. 7 and 17 were killed, and the tibias were removed for histological examination. No leg weakness appeared during the trial in Lot 2 (Cel-0Glass). In Lot 3 (cod liver oil) one transient case of leg weak ness appeared in the fifth week. This recovered after one dose of cod liver oil by medicine dropper. It is possible that the chick had not received enough cod liver oil in its feed, or pos sibly the recovery was not due to the oil but was spontaneous, a mechanical injury or other weakness having produced the symptoms.
WINDOW GLASS VS. A GLASS SUBSTITUTE
65
It is therefore evident that the condition in these chicks which developed leg weakness at seven to nine weeks of age when kept behind window glass was strongly suggestive of rickets. The bone lesions apparently were different from the condition described by Pappenheimer and Dunn·^ as early leg weakness occurring in chicks of three to four weeks of age which had been reared on a white corn ration deficient in Vitamine A. Since chicks from the Cel-0-Glass and cod liver oil lots showed no rachitic changes, it is probable that the late leg weakness or rickets that appeared in Lot 1 was due to the lack of the active rays of light, or of the antirachitic vitamine. In this re.spect the results of this experi ment resemble those of Hart, Steenbock, and Lepkovsky^, who produced leg weakness which they interpreted as rickets in chicks nine to ten weeks old, by confinement of chicks behind window glass on a yellow corn diet. GEOW^TH
The groΛvth of Lot 2 (Cel-0-Glass) Λvas normal. In Lot 1 (window glass), growth was somewhat retarded by the occur rence of leg weakness, while in Lot 3 (cod liver oil), growth was al)out normal. The average weights are given in Table I.
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
puscles. The bordering osteoblastic cells are well developed and sug gest active osteogenesis. Some of the osteoid tissue appears to be under going resorption and is surrounded by large numbers of inultinucleated osteoclasts. "In the diaphysis, the cortex and spongy bone are well developed, with practically no osteoid border. They are virtually normal in ap pearance. Chicken No. .17. Resembles No. 7, but the lesions are less pronounced. The cartilage is wider than normal and irregularly calcified. The psongiosa is abundant, and composed of numerous thin trabeculae with a slightly excessive osteoid margin. There is slight fibrosis of the marrow. Chickens Nos. .}6', //.}, .3,3, and 6S: Show no changes suggesting rickets. There Is possibly slight irregularity, and widening of the epiphyseal cartilage, but there is abundant calcium deposition in the zone of pro visional calcification. There is no excess of osteoid in the trabeculae of the spongiosa. The marrow is cellular to the epiphysis. "Diagnosis: Chicken No. 7 shows a moderate grade of anatomical rickets. The calcium deposition is defective, though not wholly lack ing, and there Is a definite "rachitic" metaphysis with excess of osteoid tissue and fibrosis of the marrow. "Chicken No. 17 shows similar changes, but less marked. "The other birds show no significant alternations from the normal."
QQ
POULTRY
SCIENCE
TABLE I Age Wks.
3 4 5 6 7 8 9
Lot 2 Cel-0-Glass Gms.
Died
34.8 55.9 83.1 117.4 163.8 199.3 252.3
1 2*
No weights taken
35.9 56.0 86.0 124.9 161.4 208.2 263.2
124.5 167.4 208.2 259.0
__ __
__ __
2t
460.5
Died
36.5 53.0 83.0
412.3
355.0 392.7
Died
Lot 3 2% Cod Liver Oil Gms.
none
361.0 $401.4
none
* Chick No. 7 AA'as given cod liver oil. which prevented its death. t Two chicks hadly afflicted were killed for pathological examination of their bones. I The average weight of t h i s lot is n o t directlj' comparable t o t h e weights of I/Ots 1 a n d 2 because of t h e presence of three or more females in Lot ·'>. which slightly lowers i t s average.
AH three lots were practically identical in growth up to and including the fourth week. With the appearance and general approach of leg weakness in the control lot (window glass). Lot 2 (glass substitute) began to make larger gains than did either Lots 1, the control, or 3 supplemented with cod liver oil. GENERAL
DISCUSSION
It is quite apparent that the group receiving sunlight through window glass suffered from leg weakness or rickets, while either sunlight through Cel-0-Grlass or cod liver oil prevented this condition. The practical adaptation of such substitutes for glass in preventing rickets or leg weakness depends to a large extent on the efficiency of the material in transmitting the shortest light waves, the time of year, and the weather. Winchester'', in tests carried on in 1925, compared the amount of short waves passing through window glass, quartz spectrograph, and Cel-0-Glass. The shortest wave lengths recorded through a quartz speetograph was 2990 Angstrom units. Through Cel-0-Glass with a quartz filter, the shortest wave length was 3010 Angstrom units. The shortest wave length through window glass with a quarter filter was 3210 Angstrom units. Winchester's measurements do not agree entirely with trials carried out on rats by Hess^ Winchester gave the point of physiological activity as beginning at 3200 Angstrom units, while
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
0 1 2
Lot 1 Winaow Glass (Control) Gms.
WINDOW
GLASS
VS. A GLASS
SUBSTITUTE
67
Ά η.
5- •ό
rî
g
10 //
IZ
s.9ro
Γ, M, / ζ 3 ^
5 6
\
Ν ÎL990 TUN
DCjU
t
-^3010 ζ
ο
r Ιαν< v > ^ l 10V(
g^oso
>af :-[
ζ
•iov.
/
3O70
3O90 3110
/ / / '
\ \ \ ϋα t.-l Vb,
3/30 C H A E T 1.
\ \ \ \ \ \ \
/
// —
\ \
\ \ \\ \ \
SEASONAL AND DAILY VARIATIONS OF T H E PKOTECTIVE W A V E L E N G T H ' S IN T H E S U N ' S SPECTKUM
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
Hess found that rays longer than between 3130 and 3020, (the exact point has not been determined) did not prevent rickets. Taking the figures from Hess, we find that Cel-0-Glass comes within 20 Angstrom units of the shortest wave length recorded through the quartz spectrograph, which in turn is Avithin 20 units of the lowest limit of the solar spectrum. Taking 3020 Angstrom units as a safe physiological point (it probably is higher), we find Cel-0-Glass then allowing the passage of 3010 units. This is 120 units shorter than the upper limit indicated by Hess as shown in Chart 1. From these data it would seem that chicks placed behind such glass substitutes should be sufficiently irradiated, and therefore protected from leg Aveakness when sufficient hours of sunlight prevail.
POULTRY
68
SCIENCE
Total rioNthlv SuNshiNe Hours 192,3 •WITH
5ΖΥκ. Av. fcox- CLabs.
3QO
-' 2.30
2.0O
>
\
/
\ /
\\ —^ \
—J~
/'' \
If ο
\
/
/
/ /
/
ίο
•ym Tw^,) flui^ ^ p t . Ot*. No*. D**-. ï û H , f t b . r\o*. Ov'f. M o ^
CHAUT 2.
TOTAL MONTHLY HOURS OP S U N S H I N E I N 1923,
W I T H 52-YEAR
AVERAGE FOB MASSACHUSEITTS
With this in mind, and the fact that broilers and early hatched chicks are raised under the conditions just mentioned, the question arises whether there are sufficient protective rays in sunlight to prevent leg weakness, and just how much is necessary. Bethke,
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
The tests by Winchester'' were made on March 6, 1925, which is not the season when the solar rays are the most potent in ultra violet light in this latitude. Hess^, in a paper presented in 1924, showed that the amount of ultra-violet light in the solar light varied greatly according to the season, the lowest protective power coming during the winter months, and the highest during the summer months. Undoubtedly this is one of the main reasons why rickets is so prevalent in children during the winter months, although other factors are also responsible. Not only are there fewer short rays reaching the earth's sur face during the winter months, but the days are shorter, with fewer hours of sunshine, due to the storms and cloudy days that are more frequent at that time of the year. See Chart 2.
WINDOW GLASS VS. A GLASS SUBSTITUTE
69
SUMMARY
1. Chicks groAvn behind Cel-0-Glass did not develop leg weakness, while others under identical conditions with the exception of quality of light received (through window glass) did develop a late leg weakness, that was found to be very similar to rickets. 2. The Cel-0-Glass group made slightly better growth than the control group. The difEerence in weight between Cel-0-Glass and control groups at the 9th week was about five times the probable error of the difference. 3. The efficiency in preventing leg weakness with a glass substitute depends on (a) its power to transmit the protective rays;
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
Kennard, and Kik'^, in trials carried out at the Ohio Experiment Station, found that chicks exposed to dii'ect sunlight one-half hour on six daj's a week, from hatching, did not develop leg weakness when fed a rachitic ration. These trials were carried on during the summer months, when the sunlight is at its maximum protective potency. In chart 1 after Hess^, the seasonal and diurnal variations in the protective region of the sun's spectrum is shown. It can be seen clearly that the hours of greatest intensity are between 10 a. m. and 2 p. m. If, therefore, the physiological point is set at 3020 Angstrum units, there will be no protection from the sunlight in the months from December to February, and only in the hours between 10 a. m. and 2 p. m. during the months of March, April, May, and September, October, and November. During June, July, and August, approximately one hour at midday are the maximum lower limits of the solar spectrum received. The number of hours of sunlight between 10 a. m. and 2 p. m. were recorded during the period of the experiment reported above, for if Hess^ results are correct, only during these hours Avould the protective rays reach the chicks. The pens were so placed that the chicks were exposed to the sunlight only during the four hours in the mid-day. The pens were flooded with approximately 15 hours of sunshine per week between the hours of 10 a. m. and 2 p. m. This is slightly over two hours per day. This proved to be sufficient to protect them against leg weakness during February and March, when the sunlight passed through Cel-0-Glass.
70
POULTRY
SCIENCE
BIBLIOGRAPHY ' H A S T , E . B . , STEENBOCK, H . , LBIPKOVSKY, S., KUSTSIEN, S . W . F . , H A L -
PIN, J . G., JOHNSON, 0 . N., T h e Influence of Ultra-Violet Light on t h e Production, Hatchability, a n d F e r t i l i t y of t h e Egg. J o u r n a l of Biologi cal Chemistry, 1925, Vol. 65. 2 H E S S , A. F . , T h e Ultraviolet Rays of t h e Sun. J o u r n a l of American Medical Association, April 4, 1925, Vol. 84, pp. 1033-1037. 3 HABT, E . B . , STEENBOCK, H . , LEPKOVSKY, S., H A L P I N , J . G., T h e Rela
tion of Light t o t h e Growth of t h e Chickens. J o u r n a l of Biological Chemistry, Vol. 58, 1923. * DK. GEORGE WINCHESTEB, R u t g e r s College, New Brunswick, N . J . Correspondence. 5 B E T H K E , R . M . , KENNABD, D . C , K I K , M . C , S u n l i g h t a n d Green
Clover a s Preventives of L e g Weakness of Chicks. Ohio Bimonthly Bulletin, Ohio A g r i c u l t u r a l E x p e r i m e n t Station, Vol. 10, No. 9, Nov.Dec. 1925. β PAPPENHEIMEE, A . M . , a n d D U N N , L . C , T h e Relation of Leg Weak
ness in Growing Chicks to M a m m a l i a n Rickets. J o u r n a l of Biological Chemistry, Vol. 66, No. 2, Dec. 1925. 7 HART,
E . B . , STEENBOCK,
H . , AND LEPKO\'SKY,
S., I S t h e
anti
r a c h i t i c factor of cod liver a i l w h e n mixed w i t h g r o u n d g r a i n s , d e s t r o y e d t h r o u g h s t o r a g e ? J o u r n a l of Biological C h e m i s t r y , 1 9 2 5 , Vol. 6 5 , p . 5 7 1 .
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
(b) the season of the year; (e) the amount of pure sunshine dur ing the mid-day hours. 4. Approximately 15 hours a week of sunshine proved suffi cient to prevent leg weakness in chicks confined behind Cel-0Glass. Probably fewer hours would still prove protective, yet it must be realized that these hours were recorded between 10 a. m. and 2 p. m., when the greatest amount of ultra violet rays reach the earth's surface.
Since the discovery that certain disorders such as rickets in children, dogs, rats, etc., and leg weakness in chicks could be corrected by irradiation with light containing ultra-violet rays, a great deal of experimental work has been carried on. The practical application of the knowledge resulting from these investigations has opened up a new field of poultry production, which up to a short time ago had been a series of unsuccessful attempts to raise chicks in confinement. Following the discovery that window glass filtered out these necessary rays, attempts were made to find substitutes for glass which Avould allow these short invisible solar light waves to pass through. Quartz glass was found to allow sufficient transmission of these rays to protect rats against rickets, but the expense in manufacturing made this kind of glass prohibitive to commercial poultrymen, for such uses as equipping brooder houses with quartz glass windows to prevent leg weakness. Comparatively recenlty, certain glass substitutes have appeared on the market at reasonable prices and advertised as possessing the power of transmitting ultra-violet light. Such substitutes if found to transmit enough of the short beneficial light rays to prevent leg weakness would have a wide usefulness in poultry rearing· and egg production. MATERIALS AND METHOD
In order to obtain definite information from actual trials carried on during the season when broilers are being raised, the following test was commenced February 8, 1926 : 75 Rhode Island Red chicks (48 hours old) were divided into three groups of 25 chicks each and confined in separate laboratory pens. All three groups received a basal ration used for the production of leg Aveakness as employed by Hart Steenbock, and as* Gel-0-Glass was used in this trial for the glass substitute.
62
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
(Received for publication 7-30-26)
WINDOW GLASS VS. A GLASS SUBSTITUTE
63
0
INCIDENCE OF LEG WEAKNESS
At the start of the trial, the three lots were of approximately the same weight. In general appearance, Lot 2 seemed slightly inferior to Lots 1 and 3, indicated mostly by their activity. Lots 1 and 3 appeared to be normal, Lot 1 containing perhaps the most active chicks. All chicks grew normally until the end of the fourth .week, when one chick in Lot 1 (window glass) showed the preliminary symptoms of leg weakness. This chick (No. 25) shoAved first a stifl:'ness of the legs, a difficulty in walking and in a short time became unable to stand any length of time Avithout frequent rests by squatting on its hocks. The hock joints became swollen, showing a discoloration, and in six days the bird died. Probably death was brought on prematurely due to the lack of strength to reach the feed hoppers or drink. The next appearance of leg weakness symptoms came during the sixth week, when two chicks, also in Lot 1 (window glass), came down much more rapidly than did the first one mentioned in this group. Soon after the symptoms appeared. Chick No. 1 lost all power to Avalk, but by fluttering the Avings and kicking its legs it was able to remain near the feed. Of the other chicks,
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
sociates\ consisting of yellow corn meal 97 parts, CaCOg 2 parts, and NaCl, 1 part. Skim milk was provided ad libitum. The chicks were confined in a comfortably warm room, each pen having an improvised hover, made from a butter tub and heated with an electric lamp. Due to the lack of shavings during the first part of the trial, cut straw was used as litter, later being replaced with wood shavings. Each pen was placed behind a separate window with a south exposure, which contained about 9 square feet of glass or substitute. Lot 1 Was placed behind window glass, and fed the basal ration as a check Lot. Lot 2 was placed behind a window of about 9 square feet of Cel-0-Glass, and fed the same basal ration as lot 1. Lot 3 was placed under the same conditions as Lot 1, but 2 per cent of cod liver oil was incorporated in the mash. The chicks were weighed individually each week.
64
POULTRY
SCIENCE
DIAGNOSIS OP LEG WEAKNESS
Bones of the two chicks (Nos. 7 and 17) killed at nine weeks of age while showing the leg wekness condition, together, with the bones of three chicks from Lot 2—Cel-0-Glass—(Nos. 33, 44, and 46), and of one chick in Lot 3 (No. 63) were fixed in formalin and submitted to Dr. A. M. Pappenheimer, College of Physicians and Surgeons, Columbia University, for examination. Dr. Pappenheimer reported as follows : "Leg bones were received from Mr. Wood in formalin, transferred to Miiller's solution for varying periods, until decalcification was suiRcient to permit sectioning. "Of the six received, two (No. 7 and No. 17) showed definite abnor malities, both grossly and microscopically. Chicken No. 7: There is fusiform enlargement of the head of the tibioflbula. Microscopically, the cartilage cells are prolonged down wards towards the shaft for a considerable distance. Near the epi physis they form an orderly alignment, but this is lost as the diaphysis is approached, and the cartilage cells form irregular masses which merge V7ith the surrounding osteoid. The matrix of the cartilage ap pears to be irregularly calcified. On the whole, the calcium deposition Is fairly abundant. "The trabeculae of the spongiosa are broad, and irregularly disposed. They are, in the subchondral zone, composed wholly or in large part of uncalcifled osteoid, including plump oval or vesicular nuclei, sug gesting metaplastic cartilage cells rather than diiferentiated bone cor-
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
No. 7, was given cod liΛ^er oil as used in Lot 3, to test its powers in preventing leg weakness. The chick partially recovered, and later came down again -viath leg weakness. During the 7th week the entire window-glass pen began to show the abnormal symptoms preliminary to the condition of leg weakness . By the end of the trial all chicks in this lot had come down with varying degrees of leg weakness. Nos. 7 and 17 were killed, and the tibias were removed for histological examination. No leg weakness appeared during the trial in Lot 2 (Cel-0Glass). In Lot 3 (cod liver oil) one transient case of leg weak ness appeared in the fifth week. This recovered after one dose of cod liver oil by medicine dropper. It is possible that the chick had not received enough cod liver oil in its feed, or pos sibly the recovery was not due to the oil but was spontaneous, a mechanical injury or other weakness having produced the symptoms.
WINDOW GLASS VS. A GLASS SUBSTITUTE
65
It is therefore evident that the condition in these chicks which developed leg weakness at seven to nine weeks of age when kept behind window glass was strongly suggestive of rickets. The bone lesions apparently were different from the condition described by Pappenheimer and Dunn·^ as early leg weakness occurring in chicks of three to four weeks of age which had been reared on a white corn ration deficient in Vitamine A. Since chicks from the Cel-0-Glass and cod liver oil lots showed no rachitic changes, it is probable that the late leg weakness or rickets that appeared in Lot 1 was due to the lack of the active rays of light, or of the antirachitic vitamine. In this re.spect the results of this experi ment resemble those of Hart, Steenbock, and Lepkovsky^, who produced leg weakness which they interpreted as rickets in chicks nine to ten weeks old, by confinement of chicks behind window glass on a yellow corn diet. GEOW^TH
The groΛvth of Lot 2 (Cel-0-Glass) Λvas normal. In Lot 1 (window glass), growth was somewhat retarded by the occur rence of leg weakness, while in Lot 3 (cod liver oil), growth was al)out normal. The average weights are given in Table I.
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
puscles. The bordering osteoblastic cells are well developed and sug gest active osteogenesis. Some of the osteoid tissue appears to be under going resorption and is surrounded by large numbers of inultinucleated osteoclasts. "In the diaphysis, the cortex and spongy bone are well developed, with practically no osteoid border. They are virtually normal in ap pearance. Chicken No. .17. Resembles No. 7, but the lesions are less pronounced. The cartilage is wider than normal and irregularly calcified. The psongiosa is abundant, and composed of numerous thin trabeculae with a slightly excessive osteoid margin. There is slight fibrosis of the marrow. Chickens Nos. .}6', //.}, .3,3, and 6S: Show no changes suggesting rickets. There Is possibly slight irregularity, and widening of the epiphyseal cartilage, but there is abundant calcium deposition in the zone of pro visional calcification. There is no excess of osteoid in the trabeculae of the spongiosa. The marrow is cellular to the epiphysis. "Diagnosis: Chicken No. 7 shows a moderate grade of anatomical rickets. The calcium deposition is defective, though not wholly lack ing, and there Is a definite "rachitic" metaphysis with excess of osteoid tissue and fibrosis of the marrow. "Chicken No. 17 shows similar changes, but less marked. "The other birds show no significant alternations from the normal."
POULTRY
SCIENCE
TABLE I Age Wks.
3 4 5 6 7 8 9
Lot 2 Cel-0-Glass Gms.
Died
34.8 55.9 83.1 117.4 163.8 199.3 252.3
1 2*
No weights taken
35.9 56.0 86.0 124.9 161.4 208.2 263.2
124.5 167.4 208.2 259.0
__ __
__ __
2t
460.5
Died
36.5 53.0 83.0
412.3
355.0 392.7
Died
Lot 3 2% Cod Liver Oil Gms.
none
361.0 $401.4
none
* Chick No. 7 AA'as given cod liver oil. which prevented its death. t Two chicks hadly afflicted were killed for pathological examination of their bones. I The average weight of t h i s lot is n o t directlj' comparable t o t h e weights of I/Ots 1 a n d 2 because of t h e presence of three or more females in Lot ·'>. which slightly lowers i t s average.
AH three lots were practically identical in growth up to and including the fourth week. With the appearance and general approach of leg weakness in the control lot (window glass). Lot 2 (glass substitute) began to make larger gains than did either Lots 1, the control, or 3 supplemented with cod liver oil. GENERAL
DISCUSSION
It is quite apparent that the group receiving sunlight through window glass suffered from leg weakness or rickets, while either sunlight through Cel-0-Grlass or cod liver oil prevented this condition. The practical adaptation of such substitutes for glass in preventing rickets or leg weakness depends to a large extent on the efficiency of the material in transmitting the shortest light waves, the time of year, and the weather. Winchester'', in tests carried on in 1925, compared the amount of short waves passing through window glass, quartz spectrograph, and Cel-0-Glass. The shortest wave lengths recorded through a quartz speetograph was 2990 Angstrom units. Through Cel-0-Glass with a quartz filter, the shortest wave length was 3010 Angstrom units. The shortest wave length through window glass with a quarter filter was 3210 Angstrom units. Winchester's measurements do not agree entirely with trials carried out on rats by Hess^ Winchester gave the point of physiological activity as beginning at 3200 Angstrom units, while
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
0 1 2
Lot 1 Winaow Glass (Control) Gms.
WINDOW
GLASS
VS. A GLASS
SUBSTITUTE
67
Ά η.
5- •ό
rî
g
10 //
IZ
s.9ro
Γ, M, / ζ 3 ^
5 6
\
Ν ÎL990 TUN
DCjU
t
-^3010 ζ
ο
r Ιαν< v > ^ l 10V(
g^oso
>af :-[
ζ
•iov.
/
3O70
3O90 3110
/ / / '
\ \ \ ϋα t.-l Vb,
3/30 C H A E T 1.
\ \ \ \ \ \ \
/
// —
\ \
\ \ \\ \ \
SEASONAL AND DAILY VARIATIONS OF T H E PKOTECTIVE W A V E L E N G T H ' S IN T H E S U N ' S SPECTKUM
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
Hess found that rays longer than between 3130 and 3020, (the exact point has not been determined) did not prevent rickets. Taking the figures from Hess, we find that Cel-0-Glass comes within 20 Angstrom units of the shortest wave length recorded through the quartz spectrograph, which in turn is Avithin 20 units of the lowest limit of the solar spectrum. Taking 3020 Angstrom units as a safe physiological point (it probably is higher), we find Cel-0-Glass then allowing the passage of 3010 units. This is 120 units shorter than the upper limit indicated by Hess as shown in Chart 1. From these data it would seem that chicks placed behind such glass substitutes should be sufficiently irradiated, and therefore protected from leg Aveakness when sufficient hours of sunlight prevail.
POULTRY
68
SCIENCE
Total rioNthlv SuNshiNe Hours 192,3 •WITH
5ΖΥκ. Av. fcox- CLabs.
3QO
-' 2.30
2.0O
>
\
/
\ /
\\ —^ \
—J~
/'' \
If ο
\
/
/
/ /
/
ίο
•ym Tw^,) flui^ ^ p t . Ot*. No*. D**-. ï û H , f t b . r\o*. Ov'f. M o ^
CHAUT 2.
TOTAL MONTHLY HOURS OP S U N S H I N E I N 1923,
W I T H 52-YEAR
AVERAGE FOB MASSACHUSEITTS
With this in mind, and the fact that broilers and early hatched chicks are raised under the conditions just mentioned, the question arises whether there are sufficient protective rays in sunlight to prevent leg weakness, and just how much is necessary. Bethke,
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
The tests by Winchester'' were made on March 6, 1925, which is not the season when the solar rays are the most potent in ultra violet light in this latitude. Hess^, in a paper presented in 1924, showed that the amount of ultra-violet light in the solar light varied greatly according to the season, the lowest protective power coming during the winter months, and the highest during the summer months. Undoubtedly this is one of the main reasons why rickets is so prevalent in children during the winter months, although other factors are also responsible. Not only are there fewer short rays reaching the earth's sur face during the winter months, but the days are shorter, with fewer hours of sunshine, due to the storms and cloudy days that are more frequent at that time of the year. See Chart 2.
WINDOW GLASS VS. A GLASS SUBSTITUTE
69
SUMMARY
1. Chicks groAvn behind Cel-0-Glass did not develop leg weakness, while others under identical conditions with the exception of quality of light received (through window glass) did develop a late leg weakness, that was found to be very similar to rickets. 2. The Cel-0-Glass group made slightly better growth than the control group. The difEerence in weight between Cel-0-Glass and control groups at the 9th week was about five times the probable error of the difference. 3. The efficiency in preventing leg weakness with a glass substitute depends on (a) its power to transmit the protective rays;
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
Kennard, and Kik'^, in trials carried out at the Ohio Experiment Station, found that chicks exposed to dii'ect sunlight one-half hour on six daj's a week, from hatching, did not develop leg weakness when fed a rachitic ration. These trials were carried on during the summer months, when the sunlight is at its maximum protective potency. In chart 1 after Hess^, the seasonal and diurnal variations in the protective region of the sun's spectrum is shown. It can be seen clearly that the hours of greatest intensity are between 10 a. m. and 2 p. m. If, therefore, the physiological point is set at 3020 Angstrum units, there will be no protection from the sunlight in the months from December to February, and only in the hours between 10 a. m. and 2 p. m. during the months of March, April, May, and September, October, and November. During June, July, and August, approximately one hour at midday are the maximum lower limits of the solar spectrum received. The number of hours of sunlight between 10 a. m. and 2 p. m. were recorded during the period of the experiment reported above, for if Hess^ results are correct, only during these hours Avould the protective rays reach the chicks. The pens were so placed that the chicks were exposed to the sunlight only during the four hours in the mid-day. The pens were flooded with approximately 15 hours of sunshine per week between the hours of 10 a. m. and 2 p. m. This is slightly over two hours per day. This proved to be sufficient to protect them against leg weakness during February and March, when the sunlight passed through Cel-0-Glass.
70
POULTRY
SCIENCE
BIBLIOGRAPHY ' H A S T , E . B . , STEENBOCK, H . , LBIPKOVSKY, S., KUSTSIEN, S . W . F . , H A L -
PIN, J . G., JOHNSON, 0 . N., T h e Influence of Ultra-Violet Light on t h e Production, Hatchability, a n d F e r t i l i t y of t h e Egg. J o u r n a l of Biologi cal Chemistry, 1925, Vol. 65. 2 H E S S , A. F . , T h e Ultraviolet Rays of t h e Sun. J o u r n a l of American Medical Association, April 4, 1925, Vol. 84, pp. 1033-1037. 3 HABT, E . B . , STEENBOCK, H . , LEPKOVSKY, S., H A L P I N , J . G., T h e Rela
tion of Light t o t h e Growth of t h e Chickens. J o u r n a l of Biological Chemistry, Vol. 58, 1923. * DK. GEORGE WINCHESTEB, R u t g e r s College, New Brunswick, N . J . Correspondence. 5 B E T H K E , R . M . , KENNABD, D . C , K I K , M . C , S u n l i g h t a n d Green
Clover a s Preventives of L e g Weakness of Chicks. Ohio Bimonthly Bulletin, Ohio A g r i c u l t u r a l E x p e r i m e n t Station, Vol. 10, No. 9, Nov.Dec. 1925. β PAPPENHEIMEE, A . M . , a n d D U N N , L . C , T h e Relation of Leg Weak
ness in Growing Chicks to M a m m a l i a n Rickets. J o u r n a l of Biological Chemistry, Vol. 66, No. 2, Dec. 1925. 7 HART,
E . B . , STEENBOCK,
H . , AND LEPKO\'SKY,
S., I S t h e
anti
r a c h i t i c factor of cod liver a i l w h e n mixed w i t h g r o u n d g r a i n s , d e s t r o y e d t h r o u g h s t o r a g e ? J o u r n a l of Biological C h e m i s t r y , 1 9 2 5 , Vol. 6 5 , p . 5 7 1 .
Downloaded from http://ps.oxfordjournals.org/ at University of California, San Diego on June 9, 2015
(b) the season of the year; (e) the amount of pure sunshine dur ing the mid-day hours. 4. Approximately 15 hours a week of sunshine proved suffi cient to prevent leg weakness in chicks confined behind Cel-0Glass. Probably fewer hours would still prove protective, yet it must be realized that these hours were recorded between 10 a. m. and 2 p. m., when the greatest amount of ultra violet rays reach the earth's surface.