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The Effect of Light and Temperature on Molting in Turkeys1
The Effect of Light and Temperature on Molting in Turkeys 1 CLYDE D. MUELLER, FRED MOULTRIE, L. F. PAYNE, H. D. SMITH AND R. E. CLEGG
Kansas State College, Manhattan, Kansas (Received for publication February 10,1950
T IS a common observation in this locality that turkeys show the presence of a considerable number of new feathers in their plumage throughout the early fall months. Such new feathers are not completely removed during ordinary dressing procedures, and the black pulp left in the feather follicles detracts from the appearance and quality of the dressed bird. Early hatched turkeys show many pinfeathers and partially grown feathers at 28 weeks of age, while birds of the same strain hatched late in the season are relatively free from pinfeathers when 28 weeks old. It has not been known whether such differences between the maturity of feathers in early and late hatched poults are conditioned by light, by temperature, or by both of these environmental factors. Host (1942) studied the effect of light conditions on plumage molts in the Willow Ptarmigan. In that species, feathers of different colors normally are present during different seasons. Exposure of experimental birds first to 12 to 14 hours of light daily and then to continuous light throughout day and night stimulated production of spring plumage during the period from November to January, when temperatures were below 0°C. Reduction 1
Contribution No. 191 from the Department of Poultry Husbandry and No. 440 from the Department of Chemistry, Kansas State College, Manhattan, Kansas.
of light to seven hours daily during February and March when temperatures ranged from 10° to 20°C. caused spring plumage to be replaced directly by winter plumage without the intervening molts which normally occur. Host concluded that in the ptarmigan molt was conditioned entirely by light and was not affected to any appreciable extent by temperature variations. Winn (1951) observed no molt in mature j uncos over a two-year period when 12 hours of light or less was provided daily. Bissonnette (1935) found that increased light periods in December induced an oestrous cycle and the following hair replacement in ferrets. Bissonnette and Wilson (1939) reported that minks exposed to light in decreasing amounts exhibited a typical winter pelt one to two months earlier than did animals exposed to natural light conditions or to subnormal temperatures. The present communication reports an attempt to assess the effects of variations in light and temperature upon feathering in turkeys. EXPERIMENTAL PROCEDURE
One hundred seventy-seven Broad Breasted Bronze poults hatched on April 5,1950, were reared in battery brooders at the Kansas State College Poultry Farm until they were four weeks old. At that time the 149 healthy poults remaining were divided into three groups and were
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MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG
IS 14
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DAYLIGHT
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9 "MAY" JUN'JUL'AUG'SEP "OCT" FIG. 1. Hours of light for the experiment. The "restricted light" was from an artificial source for pens 2, 3, and 3c. The natural daylight includes the period between sunrise and sunset.
pen 1 by fan ventilation. At 16 weeks, the length of day was reduced by IS minutes daily for 8 days, and the 10hour day was in effect from 17 to 28 weeks of age. Such a reduction in day length ensured a shorter day for this pen than for pen 1, for which the time between sunrise and sunset decreased to nearly 11 hours by the end of the experiment (see Figure 1). Pen 3 was located in the basement of the building, where artificial light was provided and the temperature was
regulated mechanically. The light regime provided was the same as for pen 2. Existing basement temperatures prevailed until the birds were 17 weeks old, after which time the refrigeration equipment was used to maintain a temperature of 60°F. When the poults were 16 weeks old, it was necessary to reduce the number to prevent crowding. The birds removed were distributed equally into 2 new pens (4 and 5) in slat-bottom outside shelters. On the same day an additional 36 poults of the same stock which had been hatched two weeks later (April 19) were divided into two lots (pens 6 and 7) and reared in shelters until 28 weeks of age under conditions identical except for the amount of light provided. Pens 4 and 6 received only natural daylight, while pens 5 and 7 received natural daylight supplemented by a 150-watt bulb for each pen, with the lights turned on automatically at the appropriate time before daylight to provide 15 hours of total light daily. At 24 weeks of age, eight toms were moved from pen 3 to a refrigerated room (pen 3c), in which the temperature was maintained at an average of 44°F. The detailed conditions of light and temperature provided for each pen are outlined in Table 1. Pens 6 and 7 received grain and mash (free choice), while all other lots were reared on an all-mash ration. Descriptions of feather growth were taken at biweekly intervals from 20 weeks of age until the end of the experiment. The molt of the primary wing feathers was recorded for each bird, because in that section the sequence of feather replacement is quite systematic, as reported by Leopold (1943) and Payne (1947). Each primary wing feather was classified by a scale ranging from 0 for a juvenile feather not molted to 10 for a completely grown postjuvenile primary. Scores of 1 to 9 designated the proportionate length of a
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transferred to pens 10 by 20 feet in size in a poultry house with facilities for regulating conditions of light and temperature. Details of construction of the house and operation of the equipment have been described by Warren et al. (1950). From 4 to 16 weeks of age, the poults in pen 1 were exposed to natural daylight and to the existing atmospheric variations in temperature. Pen 2 was entirely enclosed and twelve hours of light from a 150-watt bulb were provided daily from 4 to 16 weeks of age. The temperature variations were kept similar to those in
831
LIGHT AND TEMPERATURE EFFECTS ON MOLTING
TABLE 1.—Variations in environment provided for turkeys from 4 to 28 weeks of age Environment provided Pen
Temperature, °F.
Date of hatch 4-16 weeks
1 2 3 3c 4 5 6 7
April 5 April 5 April 5 April- 5 April 5 April 5 April 19 April 19
72 72 * *
17-24 weeks
Light, hours daily 25-28 weeks
Atmospheric variations Atmospheric variations 60 60 60 44 Atmospheric Atmospheric Atmospheric variations Atmospheric variations 54-85 67.3
17-28 weeks
Natural daylight 12 10 12 10 12 10 * Natural * 15 Natural daylight Natural 15t Variations in daylight 14-15 11-14 14.6 12.9
* Reared in pens 1, 2, and 3 from 4 to 16 weeks of age. Environment provided from 4 to 16 weeks was thus a combination of the conditions prevailing for pens 1, 2, and 3. t Pen 7 was provided 15 hours of light from 15 to 28 weeks of age.
post juvenile primary during its period of growth. For example, a feather judged to be one-half of its ultimate length was given a score of 5. Scores ranging from 11 to 20 were used to indicate relative growth in each primary belonging to the second postjuvenile plumage. The classification system used was very accurate, as judged by nearly 100 percent agreement between descriptions made on the same bird by different persons. A score ranging from 6 to 10 was used to classify the degree of molting of body feathers in the femoral feather tract. A score of 10 was given when there were practically no new feathers present, while successively lower scores represented an increase in the number of new feathers. The lowest score, 6, was used for birds with many new feathers, including some barely protruding through the skin. This classification of body molt was arbitrary, and not highly repeatable for the same bird in different handlings by the same person. The classification did serve, however, to differentiate extremes with regard to body molt, and was associated to some extent with the number of pin-
feathers present in the birds when dressed. All birds were killed and dressed at 28 weeks of age, and were scored by Professor T. B. Avery of Kansas State College for the degree of fleshing and for freedom from pinfeathers. The scores for fleshing were comparable to federal grades for dressed turkeys, while the scores given for freedom from pinfeathers ranged from 1 (many pinfeathers) to 10 (no^ pinfeathers). The dressed birds were graded without any knowledge of which lot each bird represented. One torn from each of pens 1, 3, 4, and 5 was skinned and the pelts were preserved to show comparative presence or absence of new feathers. RESULTS
Classifications of body molt at 28 weeks. The results demonstrate that turkeys reared under shorter hours of daily light possessed fewer new feathers and pinfeathers than did turkeys subjected to longer days. Those exposed to temperatures lower than the seasonal normal showed no better feathering than turkeys subjected to existing atmospheric temperatures.
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Atmospheric variations in temperature 55-89 61-80 Recorded weekly range 72.7 72.3 Calculated mean
4-16 weeks
832
MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG TABLE 2.—Frequency distribution of scores for body molt of turkeys at 28 weeks of age
Sex
Female
Male
Pen no.
Natural Natural 15
1 6 7
10 10
2 3
Natural Natural Natural 15 15
1 4 6 5 7
10 10 10
2 3 3c
Classification for body molt* 6
7
8
9
2 1 2
16 3 4
3 1 3
1 1 2
1
1 4
5 5
2 5 1 5 2
2 7 6 1 4
5 5
1
10
7.14 7.33 7.45 9 6
2 1 3 2 1 3 2 2
Av.
9.53 9.00 7.33 7.17 7.50 7.31 7.00
7 1 6
9.70 9.00 9.75
* Highest scores represent greatest freedom from new feathers.
A frequency distribution is given in Table 2, showing scores for the classification of body molt in live birds. Considerably higher scores were recorded for birds restricted to 10 hours of light from 17 to 28 weeks of age than for birds receiving more light during the same period. The data may be summarized further as follows: Length of day, 17 to 28 weeks of age 10 hours Natural light 15 hours
Percentage of birds in two most desirable classes Females Males 81 96 7 18 18 IS
It is of interest to note that by the standards used in classifying the turkeys at 28 weeks of age for body molt, the scores recorded for males were somewhat higher than those noted for females. Appearance of dressed birds. The frequency distribution for the number of birds receiving each score for number of pinfeathers present when dressed is given in Table 3. It should be noted that birds from pens 6 and 7 were hatched two weeks later than all other poults in the experiment and, therefore, were dressed two weeks
later than the other turkeys. The scores for dressed appearance were considerably higher for birds from pens 6 and 7 than for those from pens 4 and 5, which had received the same respective treatments over a period two weeks earlier during the season. Such differences had not been recorded for the body-molt condition of the same birds when alive. The birds from pens 1, 2, 3, 3c, 4, and 5 were killed and dressed on October 20, 1950, and were classified on October 21. Among that group, most of the birds with practically no pinfeathers were those reared under conditions of restricted light, as shown by the following summary: Length of day, 17 to 28 weeks of age 10 hours Natural light 15 hours
Percentage of birds in 4 most desirable classes Females Males 95 68 18 29 — 25
Of special interest is the fact that the scores for freedom from pinfeathers listed in Tables 2 and 3 were slightly better for both live and dressed birds from pen 2 than for birds from pens 3 and 3c. Light conditions were the same for those three pens, but the temperature was lower for
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Hours light 17-28 weeks
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L I G H T AND T E M P E R A T U R E E F F E C T S ON M O L T I N G
TABLE 3.—Frequency distribution of scores for freedom from pinfeathers in dressed turkeys
Sex
Female
Male
Hours light 17-28 weeks
Classification of dressed appearance*
Pen
1 6 7
10 10
2 3
Natural Natural Natural 15 15
1 4 6 5 7
10 10 10
2 3 3c
5
6
7
7
6
5
4 1
1 4 1
1 6 4
2
1 1
6 3
1 2 1 4 3
1 5 5 3 1
2
4 2 3
3
8
9
10
Av.
3 3
2 7
1
5.05 8.43 8.70
4 5
3 7
1
2
2
2
1
3
2 1
7.80 8.12 5.50 5.35 7.50 5.50 7.14
•
7.45 7.67 6.12
* Highest scores represent most desirable condition.
FIG. 2. Inside surface of pelts from turkeys skinned at 28 weeks of age. The dark spots are follicles filled with pulp at the base of pinfeathers and partly grown feathers. Body-molt scores in live birds were taken in the femoral tract, the area in photographs lateral to " X . " (A) Tom reared in pen 3 with 10 hours of light from 17 to 28 weeks of age. The body-molt score in live bird was 9. (B) Tom reared in pen 5 with 15 hours of light from 17 to 28 weeks. The body-molt score in live bird was 6. Many more pinfeathers are evident than in 'A).
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Natural Natural 15
1-4
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MUELLEB, MOULTRIE, PAYNE, SMITH AND CLEGG
pens 3 and 3c. There were no apparent differences in feathering between the birds receiving natural light and those receiving 15 hours of light daily. A comparison between the number of
MALES RESTRICTED LIGHT
RESTRICTED LIGHT
20
22
24
26
28
AGE IN WEEKS FIG. 3. Graphs stowing the average scores for body molt from 20 to 28 weeks of age in turkeys reared under different light conditions. Higher scores indicate fewer new feathers or pinfeathers on turkeys receiving restricted light (solid line) than on turkeys exposed to natural daylight or to 15 hours of light daily (dashed line).
new feathers in the skin of a turkey male reared under conditions of restricted light and the number for a male exposed to 15 hours of light from 17 to 28 weeks is shown in Figure 2. The data for birds dressed on October 20 indicate that degree of fleshing was not affected consistently by variations in light. Of the females reared under restricted
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FEMALES
light, 77 percent received one of the three highest fleshing scores; while 62 percent of the females subjected to more light received those scores. The proportions of males in the same classes for those with restricted light and those exposed to longer days were 64 and 74 percent, respectively. Changes in body molt with age. The classifications for body molt at 20 and 22 weeks of age showed no consistent differences among pens of turkeys under various environments. The scores, slightly lower at 22 weeks than at 20 weeks of age, probably reflect differences in the arbitrary standards for classification of the molt condition. From 22 to 28 weeks of age, the scores for body molt increased sharply for birds receiving only 10 hours of light. During the same period, decreasing bodymolt scores were recorded for the other lots, which received natural daylight or 15 hours of light daily. Apparently, in birds with high scores for molt, very few feathers in the femoral tract were replaced after 24 weeks of age. A comparison of body molt by age and by light treatment for each sex is given in Figure 3. Molt in wing primaries. Classifications of molt in primaries were first recorded when the turkeys were 20 weeks old, at which time the birds in pens 2 and 3 had been subjected to 10 hours of light for a 3-week period. There were slight differences in wing molt among pens receiving different amounts of light, and in all lots the males were somewhat slower than the females to molt primaries 1, 5, 6, 7, and 8, numbering laterally from the axial feather. Primaries number 2,3, and 4 were completely grown out (postjuvenile plumage) in all birds, and primaries number 9 and 10 were still of the juvenile plumage in all except two females in pen 6 and one in pen 7. The differences among pens with regard to molt in primaries increased
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LIGHT AND TEMPERATURE EFFECTS ON MOLTING
during the period from 20 to 28 weeks of age, and the difference between sexes was maintained. The effect of length of day on molt in primaries at 28 weeks of age is shown in Figure 4. The average scores for primary molt
molted the postjuvenile primaries number 1 and 2 are given in Table 4. Some evidence that changes in the length of day can affect the molting process within a relatively short time was obtained from birds in pens 4 and 5, which were reared until 16 weeks of age under TABLE 4.—The effect of sex and environmental light
on molt in primary wing feathers of 4 28 weeks of age
Sex
Number
Restricted
Female Male
31 23
Not Restricted
Female Male
43 54
Percentage of birds molting primary number*
71 35 98 96
0 4
71 4
58 11
98 96
28 18
* The molts indicated are replacement of the juvenile plumage for primaries 9 and 10 and the first postjuvenile plumage for primaries 1 and 2.
TABLE 5.—Chi-square values for distribution of scores
for molt in femoral tract, molt in primaries, and score for dressed appearance* Characteristic measured Dressed score for pin feathers Body molt, 28 wks. Body molt, 26 wks. Body molt, 24 wks. Primary molt, 28 wks. Primary No. 1 Primary No. 2 . Primary No. 8 Primary No. 9
10987 6 5 4 3 2 PRIMARY FIG. 4. A comparison of the average molt score for wing primaries at 28 weeks of age in turkeys exposed to only 10 hours of light from 17 to 28 weeks (shaded bars), and the average scores for those receiving natural daylight or 15 hours of light daily (solid bars). Molting was inhibited by restriction of light.
reflect the proportion of birds which molted rather than the relative growth of the primary after it emerged. The proportion of birds under different light treatments which molted the juvenile primaries number 9 and 10, and that which
20.0 11.3
13.3 5.5 16.9
Body molt score 28 wks.
26 wks. 62.3
62.3 16.6
15.2
21.8 15.9
* The significant values of chi-square (P = <.05) indicate that a high score in one of the molt traits is associated with a high score for the other trait.
the various conditions present in pens 1, 2, and 3. The molt score for pen 4 and pen 5 birds at 20 weeks varied according to the environment of the turkeys previous to 16 weeks of age as follows: Length of day 4 to 16 weeks of age Natural daylight 12 hours
Number 17 13
Av. score for primary no. 1 14.3 12.5
The turkeys which had been exposed to more than 12 hours of light previous to 16 weeks of age showed more molt
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Length of day
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MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG
Scores for primaries No. 1 and No. 9 at 26 weeks. Scores for primaries No. 2 and No. 9 at 26 weeks. Scores for molt of body and of primary No. 1 at 26 weeks. Scores for molt of body and of primary No. 1 at 24 weeks. Scores for molt of body and of primary No. 8 at 24 weeks. Scores for molt of body and of primary No. 9 at 24 weeks.
Individuals with a high classification for one of the molt scores listed tended to have a high classification: for the other molt score. Number of primaries. Six of the 156 turkeys classified for molt after reaching 20 weeks of age had only nine primaries in each wing. Two of them were females and four were males. No cause for this variation from the normal condition The chi-square values listed in Table 5 could be established because of the fact indicate a rather close association bethat each of the birds with only nine tween the molt scores compared. This was primaries was in a different pen, and they to be expected since each of the traits were not closely related to each other. has been shown to be affected by variaIt was of interest to note in those turkeys, tions in light. The extent to which the that the pattern of molt for the inside score for one trait was associated with two and outside four primaries was comthe score for another may be shown by parable to that for the same primaries of the following example: birds with the normal number. Molting Number of individuals with Body moll at feather score of dressed birds apparently proceeded from the axial 26 weeks Best 4 Poorest 6 feather laterally in the normal sequence. classes classes The two birds which had been reared Best 2 classes 34 14 under restricted light retained the last Poorest classes 23 37 two primaries (No. 8 and No. 9 from the Of the individuals which ranked in the axial) of the juvenile plumage. Three of group with highest scores for body molt the birds on natural or extended light at 26 weeks of age, 71 percent ranked in retained the last juvenile primary (No. 9 the group with highest scores for freedom from the axial) and one bird molted from pinfeathers when dressed two weeks all nine juvenile primaries. later. Of those with lowest scores for body molt at 26 weeks of age, 62 percent later DISCUSSION ranked in the group with lowest scores for dressed appearance. The foregoing data indicate a definite By similar tests, it was determined that effect of length of day on molting in turdefinite associations existed between the keys. It should be noted that all the light following pairs of molt scores: received by the birds under restricted light conditions was from an artificial Scores for primaries No. 1 and No. 9 at 28 weeks. Scores for primaries No. 2 and No. 9 at 28 weeks. source. It seems unlikely that the source
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than did those which were restricted to 12 hours of light before that time. Interrelationships of wing molt, body moll, and dressed appearance. In Order to test these relationships, the individuals were divided into two groups with respect to one characteristic, and then divided into two groups with respect to the other characteristic. An attempt was made to include nearly one-half of the individuals in the "best" and one-half in the "poorest" group with respect to each molt score. Chi-square values were calculated to determine whether the distribution of individuals in such contingency tables deviated from that which would be expected if the two traits were not associated.
LIGHT AND TEMPERATURE EFFECTS ON MOLTING
The variations in amount of molting due to differences in light make it necessary to account for such environmental factors when establishing patterns of molt. The April-hatched turkeys in this experiment subjected to natural light conditions showed more molting at a given age than did those described by Payne (1947) which were hatched in May. The present results, as best demonstrated by the data presented in Figure 4, show that the ultimate number of feathers molted in the juvenile and postjuvenile plumage is conditioned by light variaations. It is possible that this factor influenced to some extent the results reported by Leopold (1943), who stated that domestic turkeys retained only the distal juvenile primary; while the two distal primaries were not replaced in M. G. syhestris, a wild turkey. The distal
juvenile primary is also retained during the first laying year in many chickens, according to Marble (1934) and Warren and Gordon (1935). It is felt that variations in length of day probably account for the fact that early-hatched poults do not show a proper finish of feathers before the short days of winter. The present data lend no support to the belief held by many that cold weather is required to produce turkeys free of pinfeathers. SUMMARY
Restriction of light to 12 hours daily from 4 to 16 weeks of age and to 10 hours daily from 17 to 28 weeks of age resulted in reduced molting of the first postjuvenile plumage in turkeys. When such turkeys were dressed, fewer pinfeathers were noted than were present for birds of the same age and origin reared under natural daylight or for those provided 15 hours of light daily. Classification scores for degree of molting in wing primaries and in body feathers of the femoral tract were associated with scores of the dressed appearance. Temperature variations within the range from 44° to 70°F. had no apparent influence on molting. Turkeys reared under the restricted light conditions were relatively free of pinfeathers at 24 weeks of age. Such birds when dressed on October 20 at 28 weeks of age exhibited an appearance comparable to that normally expected a month later in turkeys reared under natural light. REFERENCES Bissonnette, T. H., 193S. Relations of hair cycles in ferrets to changes in the anterior hypophysis and to light cycles. Anat. Rec. 63: 159-168. Bissonnette, T. H., and E. Wilson, 1939. Shortening daylight periods between May IS and September 12 and the pelt cycle of the mink. Science 89: 418HU9.
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of light rather than the length of day would be a factor. Ordinarily, artificial light of reasonable candle power is a satisfactory substitute for sunlight in rearing poultry when adequate rations are employed. It is a well known fact that increased light stimulates reproductive activity in many species of birds. It has been shown by Warren et al. (1950) and by Mueller et al. (1951) that increased light inhibits or suppresses the normal progress of the annual molt following a season of egg production in the domestic fowl, and that temperature variations have a minor effect on that molt. It would seem that the molts which precede sexual maturity, as studied in the present experiment, must be regulated by different physiological processes because the inhibitory effect on molt was produced by restricting the light. The molt preceding sexual maturity and the fur cycles of some animals apparently are affected in a similar fashion by variations in light.
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ASSOCIATION NOTES
Host, P., 1942. Effect of light on the moults and sequences of plumage in the Willow Ptarmigan. Auk 59: 388-403. Leopold, A. S., 1943. The molts of young wild and domestic turkeys. Condor 45: 133-145. Marble, D. R., 1934. Relation of juvenile plumage to growth and sexual maturity. Poultry Sci. 13: 195-201. Mueller, C. D., T. B. Avery, H. D. Smith and R. E. Clegg, 1951. Effects of controlled light and temperature for laying hens. Poultry Sci. 30:679-686.
Payne, L. F., 1947. Frequency of the tail and wing molt in turkeys. Poultry Sci. 26: 52-60. Warren, D. C , R. Conrad, A. E. Schumacher and T. B. Avery, 1950. Effects of fluctuating environment on laying hens. Kansas Agr. Expt. Sta. Tech. Bui. 68. Warren, D. C , and C. D. Gordon, 1935. The sequence of appearance, molt, and replacement of the juvenile remiges of some domestic birds. J. Agr. Res. 51:459-470. Winn, H. S., 1951. Personal communication.
{Continued from page 8ZS)
He is a member of the Poultry Science Association, the American Chemical Society, Society for Experimental Biology and Medicine, American Association for the Advancement of Science, Texas Academy of Science, American Institute of Nutrition, Federated Societies of Biology, Sigma Xi and Gamma Alpha. POULTRY SCIENCE RESEARCH PRIZE
W. E. BRILES
Winner of the Poultry Science Research Prize
tural and Mechanical College and Texas Agricultural Experiment Station as Professor of Poultry Husbandry and Biochemistry and Nutrition.
The Poultry Science Association's Research Prize of one hundred dollars for the outstanding research paper published during the preceding year was presented to Dr. W. E. Briles, Department of Poultry Husbandry, Texas Agricultural and Mechanical College System, College Station, Texas. The prize was awarded for his studies at the University of Wisconsin in collaboration with W. H. McGibbon and M. R. Irwin. The paper was entitled, "On Multiple Alleles Effecting Cellular Antigens in the Chicken," and was published iriGenetics 35: 633-652, 1950. Worthie Elwood Briles was born January 31, 1918 at Italy, Texas. He graduated from Polytechnic High School, Fort Worth, Texas, in 1936 and attended North Texas Agricultural College, Arling-
(Continued on page 85S)
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Association Notes
Kansas State College, Manhattan, Kansas (Received for publication February 10,1950
T IS a common observation in this locality that turkeys show the presence of a considerable number of new feathers in their plumage throughout the early fall months. Such new feathers are not completely removed during ordinary dressing procedures, and the black pulp left in the feather follicles detracts from the appearance and quality of the dressed bird. Early hatched turkeys show many pinfeathers and partially grown feathers at 28 weeks of age, while birds of the same strain hatched late in the season are relatively free from pinfeathers when 28 weeks old. It has not been known whether such differences between the maturity of feathers in early and late hatched poults are conditioned by light, by temperature, or by both of these environmental factors. Host (1942) studied the effect of light conditions on plumage molts in the Willow Ptarmigan. In that species, feathers of different colors normally are present during different seasons. Exposure of experimental birds first to 12 to 14 hours of light daily and then to continuous light throughout day and night stimulated production of spring plumage during the period from November to January, when temperatures were below 0°C. Reduction 1
Contribution No. 191 from the Department of Poultry Husbandry and No. 440 from the Department of Chemistry, Kansas State College, Manhattan, Kansas.
of light to seven hours daily during February and March when temperatures ranged from 10° to 20°C. caused spring plumage to be replaced directly by winter plumage without the intervening molts which normally occur. Host concluded that in the ptarmigan molt was conditioned entirely by light and was not affected to any appreciable extent by temperature variations. Winn (1951) observed no molt in mature j uncos over a two-year period when 12 hours of light or less was provided daily. Bissonnette (1935) found that increased light periods in December induced an oestrous cycle and the following hair replacement in ferrets. Bissonnette and Wilson (1939) reported that minks exposed to light in decreasing amounts exhibited a typical winter pelt one to two months earlier than did animals exposed to natural light conditions or to subnormal temperatures. The present communication reports an attempt to assess the effects of variations in light and temperature upon feathering in turkeys. EXPERIMENTAL PROCEDURE
One hundred seventy-seven Broad Breasted Bronze poults hatched on April 5,1950, were reared in battery brooders at the Kansas State College Poultry Farm until they were four weeks old. At that time the 149 healthy poults remaining were divided into three groups and were
829
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I
830
MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG
IS 14
^
s.
/
\ \ . NATURAL
^
\
^ 13
—
-> •« 0
DAYLIGHT
x
\ RESTRICTED LIGHT
\
\
\
W II
\
g.o
\
—
9 "MAY" JUN'JUL'AUG'SEP "OCT" FIG. 1. Hours of light for the experiment. The "restricted light" was from an artificial source for pens 2, 3, and 3c. The natural daylight includes the period between sunrise and sunset.
pen 1 by fan ventilation. At 16 weeks, the length of day was reduced by IS minutes daily for 8 days, and the 10hour day was in effect from 17 to 28 weeks of age. Such a reduction in day length ensured a shorter day for this pen than for pen 1, for which the time between sunrise and sunset decreased to nearly 11 hours by the end of the experiment (see Figure 1). Pen 3 was located in the basement of the building, where artificial light was provided and the temperature was
regulated mechanically. The light regime provided was the same as for pen 2. Existing basement temperatures prevailed until the birds were 17 weeks old, after which time the refrigeration equipment was used to maintain a temperature of 60°F. When the poults were 16 weeks old, it was necessary to reduce the number to prevent crowding. The birds removed were distributed equally into 2 new pens (4 and 5) in slat-bottom outside shelters. On the same day an additional 36 poults of the same stock which had been hatched two weeks later (April 19) were divided into two lots (pens 6 and 7) and reared in shelters until 28 weeks of age under conditions identical except for the amount of light provided. Pens 4 and 6 received only natural daylight, while pens 5 and 7 received natural daylight supplemented by a 150-watt bulb for each pen, with the lights turned on automatically at the appropriate time before daylight to provide 15 hours of total light daily. At 24 weeks of age, eight toms were moved from pen 3 to a refrigerated room (pen 3c), in which the temperature was maintained at an average of 44°F. The detailed conditions of light and temperature provided for each pen are outlined in Table 1. Pens 6 and 7 received grain and mash (free choice), while all other lots were reared on an all-mash ration. Descriptions of feather growth were taken at biweekly intervals from 20 weeks of age until the end of the experiment. The molt of the primary wing feathers was recorded for each bird, because in that section the sequence of feather replacement is quite systematic, as reported by Leopold (1943) and Payne (1947). Each primary wing feather was classified by a scale ranging from 0 for a juvenile feather not molted to 10 for a completely grown postjuvenile primary. Scores of 1 to 9 designated the proportionate length of a
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transferred to pens 10 by 20 feet in size in a poultry house with facilities for regulating conditions of light and temperature. Details of construction of the house and operation of the equipment have been described by Warren et al. (1950). From 4 to 16 weeks of age, the poults in pen 1 were exposed to natural daylight and to the existing atmospheric variations in temperature. Pen 2 was entirely enclosed and twelve hours of light from a 150-watt bulb were provided daily from 4 to 16 weeks of age. The temperature variations were kept similar to those in
831
LIGHT AND TEMPERATURE EFFECTS ON MOLTING
TABLE 1.—Variations in environment provided for turkeys from 4 to 28 weeks of age Environment provided Pen
Temperature, °F.
Date of hatch 4-16 weeks
1 2 3 3c 4 5 6 7
April 5 April 5 April 5 April- 5 April 5 April 5 April 19 April 19
72 72 * *
17-24 weeks
Light, hours daily 25-28 weeks
Atmospheric variations Atmospheric variations 60 60 60 44 Atmospheric Atmospheric Atmospheric variations Atmospheric variations 54-85 67.3
17-28 weeks
Natural daylight 12 10 12 10 12 10 * Natural * 15 Natural daylight Natural 15t Variations in daylight 14-15 11-14 14.6 12.9
* Reared in pens 1, 2, and 3 from 4 to 16 weeks of age. Environment provided from 4 to 16 weeks was thus a combination of the conditions prevailing for pens 1, 2, and 3. t Pen 7 was provided 15 hours of light from 15 to 28 weeks of age.
post juvenile primary during its period of growth. For example, a feather judged to be one-half of its ultimate length was given a score of 5. Scores ranging from 11 to 20 were used to indicate relative growth in each primary belonging to the second postjuvenile plumage. The classification system used was very accurate, as judged by nearly 100 percent agreement between descriptions made on the same bird by different persons. A score ranging from 6 to 10 was used to classify the degree of molting of body feathers in the femoral feather tract. A score of 10 was given when there were practically no new feathers present, while successively lower scores represented an increase in the number of new feathers. The lowest score, 6, was used for birds with many new feathers, including some barely protruding through the skin. This classification of body molt was arbitrary, and not highly repeatable for the same bird in different handlings by the same person. The classification did serve, however, to differentiate extremes with regard to body molt, and was associated to some extent with the number of pin-
feathers present in the birds when dressed. All birds were killed and dressed at 28 weeks of age, and were scored by Professor T. B. Avery of Kansas State College for the degree of fleshing and for freedom from pinfeathers. The scores for fleshing were comparable to federal grades for dressed turkeys, while the scores given for freedom from pinfeathers ranged from 1 (many pinfeathers) to 10 (no^ pinfeathers). The dressed birds were graded without any knowledge of which lot each bird represented. One torn from each of pens 1, 3, 4, and 5 was skinned and the pelts were preserved to show comparative presence or absence of new feathers. RESULTS
Classifications of body molt at 28 weeks. The results demonstrate that turkeys reared under shorter hours of daily light possessed fewer new feathers and pinfeathers than did turkeys subjected to longer days. Those exposed to temperatures lower than the seasonal normal showed no better feathering than turkeys subjected to existing atmospheric temperatures.
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Atmospheric variations in temperature 55-89 61-80 Recorded weekly range 72.7 72.3 Calculated mean
4-16 weeks
832
MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG TABLE 2.—Frequency distribution of scores for body molt of turkeys at 28 weeks of age
Sex
Female
Male
Pen no.
Natural Natural 15
1 6 7
10 10
2 3
Natural Natural Natural 15 15
1 4 6 5 7
10 10 10
2 3 3c
Classification for body molt* 6
7
8
9
2 1 2
16 3 4
3 1 3
1 1 2
1
1 4
5 5
2 5 1 5 2
2 7 6 1 4
5 5
1
10
7.14 7.33 7.45 9 6
2 1 3 2 1 3 2 2
Av.
9.53 9.00 7.33 7.17 7.50 7.31 7.00
7 1 6
9.70 9.00 9.75
* Highest scores represent greatest freedom from new feathers.
A frequency distribution is given in Table 2, showing scores for the classification of body molt in live birds. Considerably higher scores were recorded for birds restricted to 10 hours of light from 17 to 28 weeks of age than for birds receiving more light during the same period. The data may be summarized further as follows: Length of day, 17 to 28 weeks of age 10 hours Natural light 15 hours
Percentage of birds in two most desirable classes Females Males 81 96 7 18 18 IS
It is of interest to note that by the standards used in classifying the turkeys at 28 weeks of age for body molt, the scores recorded for males were somewhat higher than those noted for females. Appearance of dressed birds. The frequency distribution for the number of birds receiving each score for number of pinfeathers present when dressed is given in Table 3. It should be noted that birds from pens 6 and 7 were hatched two weeks later than all other poults in the experiment and, therefore, were dressed two weeks
later than the other turkeys. The scores for dressed appearance were considerably higher for birds from pens 6 and 7 than for those from pens 4 and 5, which had received the same respective treatments over a period two weeks earlier during the season. Such differences had not been recorded for the body-molt condition of the same birds when alive. The birds from pens 1, 2, 3, 3c, 4, and 5 were killed and dressed on October 20, 1950, and were classified on October 21. Among that group, most of the birds with practically no pinfeathers were those reared under conditions of restricted light, as shown by the following summary: Length of day, 17 to 28 weeks of age 10 hours Natural light 15 hours
Percentage of birds in 4 most desirable classes Females Males 95 68 18 29 — 25
Of special interest is the fact that the scores for freedom from pinfeathers listed in Tables 2 and 3 were slightly better for both live and dressed birds from pen 2 than for birds from pens 3 and 3c. Light conditions were the same for those three pens, but the temperature was lower for
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Hours light 17-28 weeks
833
L I G H T AND T E M P E R A T U R E E F F E C T S ON M O L T I N G
TABLE 3.—Frequency distribution of scores for freedom from pinfeathers in dressed turkeys
Sex
Female
Male
Hours light 17-28 weeks
Classification of dressed appearance*
Pen
1 6 7
10 10
2 3
Natural Natural Natural 15 15
1 4 6 5 7
10 10 10
2 3 3c
5
6
7
7
6
5
4 1
1 4 1
1 6 4
2
1 1
6 3
1 2 1 4 3
1 5 5 3 1
2
4 2 3
3
8
9
10
Av.
3 3
2 7
1
5.05 8.43 8.70
4 5
3 7
1
2
2
2
1
3
2 1
7.80 8.12 5.50 5.35 7.50 5.50 7.14
•
7.45 7.67 6.12
* Highest scores represent most desirable condition.
FIG. 2. Inside surface of pelts from turkeys skinned at 28 weeks of age. The dark spots are follicles filled with pulp at the base of pinfeathers and partly grown feathers. Body-molt scores in live birds were taken in the femoral tract, the area in photographs lateral to " X . " (A) Tom reared in pen 3 with 10 hours of light from 17 to 28 weeks of age. The body-molt score in live bird was 9. (B) Tom reared in pen 5 with 15 hours of light from 17 to 28 weeks. The body-molt score in live bird was 6. Many more pinfeathers are evident than in 'A).
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Natural Natural 15
1-4
834
MUELLEB, MOULTRIE, PAYNE, SMITH AND CLEGG
pens 3 and 3c. There were no apparent differences in feathering between the birds receiving natural light and those receiving 15 hours of light daily. A comparison between the number of
MALES RESTRICTED LIGHT
RESTRICTED LIGHT
20
22
24
26
28
AGE IN WEEKS FIG. 3. Graphs stowing the average scores for body molt from 20 to 28 weeks of age in turkeys reared under different light conditions. Higher scores indicate fewer new feathers or pinfeathers on turkeys receiving restricted light (solid line) than on turkeys exposed to natural daylight or to 15 hours of light daily (dashed line).
new feathers in the skin of a turkey male reared under conditions of restricted light and the number for a male exposed to 15 hours of light from 17 to 28 weeks is shown in Figure 2. The data for birds dressed on October 20 indicate that degree of fleshing was not affected consistently by variations in light. Of the females reared under restricted
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FEMALES
light, 77 percent received one of the three highest fleshing scores; while 62 percent of the females subjected to more light received those scores. The proportions of males in the same classes for those with restricted light and those exposed to longer days were 64 and 74 percent, respectively. Changes in body molt with age. The classifications for body molt at 20 and 22 weeks of age showed no consistent differences among pens of turkeys under various environments. The scores, slightly lower at 22 weeks than at 20 weeks of age, probably reflect differences in the arbitrary standards for classification of the molt condition. From 22 to 28 weeks of age, the scores for body molt increased sharply for birds receiving only 10 hours of light. During the same period, decreasing bodymolt scores were recorded for the other lots, which received natural daylight or 15 hours of light daily. Apparently, in birds with high scores for molt, very few feathers in the femoral tract were replaced after 24 weeks of age. A comparison of body molt by age and by light treatment for each sex is given in Figure 3. Molt in wing primaries. Classifications of molt in primaries were first recorded when the turkeys were 20 weeks old, at which time the birds in pens 2 and 3 had been subjected to 10 hours of light for a 3-week period. There were slight differences in wing molt among pens receiving different amounts of light, and in all lots the males were somewhat slower than the females to molt primaries 1, 5, 6, 7, and 8, numbering laterally from the axial feather. Primaries number 2,3, and 4 were completely grown out (postjuvenile plumage) in all birds, and primaries number 9 and 10 were still of the juvenile plumage in all except two females in pen 6 and one in pen 7. The differences among pens with regard to molt in primaries increased
835
LIGHT AND TEMPERATURE EFFECTS ON MOLTING
during the period from 20 to 28 weeks of age, and the difference between sexes was maintained. The effect of length of day on molt in primaries at 28 weeks of age is shown in Figure 4. The average scores for primary molt
molted the postjuvenile primaries number 1 and 2 are given in Table 4. Some evidence that changes in the length of day can affect the molting process within a relatively short time was obtained from birds in pens 4 and 5, which were reared until 16 weeks of age under TABLE 4.—The effect of sex and environmental light
on molt in primary wing feathers of 4 28 weeks of age
Sex
Number
Restricted
Female Male
31 23
Not Restricted
Female Male
43 54
Percentage of birds molting primary number*
71 35 98 96
0 4
71 4
58 11
98 96
28 18
* The molts indicated are replacement of the juvenile plumage for primaries 9 and 10 and the first postjuvenile plumage for primaries 1 and 2.
TABLE 5.—Chi-square values for distribution of scores
for molt in femoral tract, molt in primaries, and score for dressed appearance* Characteristic measured Dressed score for pin feathers Body molt, 28 wks. Body molt, 26 wks. Body molt, 24 wks. Primary molt, 28 wks. Primary No. 1 Primary No. 2 . Primary No. 8 Primary No. 9
10987 6 5 4 3 2 PRIMARY FIG. 4. A comparison of the average molt score for wing primaries at 28 weeks of age in turkeys exposed to only 10 hours of light from 17 to 28 weeks (shaded bars), and the average scores for those receiving natural daylight or 15 hours of light daily (solid bars). Molting was inhibited by restriction of light.
reflect the proportion of birds which molted rather than the relative growth of the primary after it emerged. The proportion of birds under different light treatments which molted the juvenile primaries number 9 and 10, and that which
20.0 11.3
13.3 5.5 16.9
Body molt score 28 wks.
26 wks. 62.3
62.3 16.6
15.2
21.8 15.9
* The significant values of chi-square (P = <.05) indicate that a high score in one of the molt traits is associated with a high score for the other trait.
the various conditions present in pens 1, 2, and 3. The molt score for pen 4 and pen 5 birds at 20 weeks varied according to the environment of the turkeys previous to 16 weeks of age as follows: Length of day 4 to 16 weeks of age Natural daylight 12 hours
Number 17 13
Av. score for primary no. 1 14.3 12.5
The turkeys which had been exposed to more than 12 hours of light previous to 16 weeks of age showed more molt
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Length of day
836
MUELLER, MOULTRIE, PAYNE, SMITH AND CLEGG
Scores for primaries No. 1 and No. 9 at 26 weeks. Scores for primaries No. 2 and No. 9 at 26 weeks. Scores for molt of body and of primary No. 1 at 26 weeks. Scores for molt of body and of primary No. 1 at 24 weeks. Scores for molt of body and of primary No. 8 at 24 weeks. Scores for molt of body and of primary No. 9 at 24 weeks.
Individuals with a high classification for one of the molt scores listed tended to have a high classification: for the other molt score. Number of primaries. Six of the 156 turkeys classified for molt after reaching 20 weeks of age had only nine primaries in each wing. Two of them were females and four were males. No cause for this variation from the normal condition The chi-square values listed in Table 5 could be established because of the fact indicate a rather close association bethat each of the birds with only nine tween the molt scores compared. This was primaries was in a different pen, and they to be expected since each of the traits were not closely related to each other. has been shown to be affected by variaIt was of interest to note in those turkeys, tions in light. The extent to which the that the pattern of molt for the inside score for one trait was associated with two and outside four primaries was comthe score for another may be shown by parable to that for the same primaries of the following example: birds with the normal number. Molting Number of individuals with Body moll at feather score of dressed birds apparently proceeded from the axial 26 weeks Best 4 Poorest 6 feather laterally in the normal sequence. classes classes The two birds which had been reared Best 2 classes 34 14 under restricted light retained the last Poorest classes 23 37 two primaries (No. 8 and No. 9 from the Of the individuals which ranked in the axial) of the juvenile plumage. Three of group with highest scores for body molt the birds on natural or extended light at 26 weeks of age, 71 percent ranked in retained the last juvenile primary (No. 9 the group with highest scores for freedom from the axial) and one bird molted from pinfeathers when dressed two weeks all nine juvenile primaries. later. Of those with lowest scores for body molt at 26 weeks of age, 62 percent later DISCUSSION ranked in the group with lowest scores for dressed appearance. The foregoing data indicate a definite By similar tests, it was determined that effect of length of day on molting in turdefinite associations existed between the keys. It should be noted that all the light following pairs of molt scores: received by the birds under restricted light conditions was from an artificial Scores for primaries No. 1 and No. 9 at 28 weeks. Scores for primaries No. 2 and No. 9 at 28 weeks. source. It seems unlikely that the source
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than did those which were restricted to 12 hours of light before that time. Interrelationships of wing molt, body moll, and dressed appearance. In Order to test these relationships, the individuals were divided into two groups with respect to one characteristic, and then divided into two groups with respect to the other characteristic. An attempt was made to include nearly one-half of the individuals in the "best" and one-half in the "poorest" group with respect to each molt score. Chi-square values were calculated to determine whether the distribution of individuals in such contingency tables deviated from that which would be expected if the two traits were not associated.
LIGHT AND TEMPERATURE EFFECTS ON MOLTING
The variations in amount of molting due to differences in light make it necessary to account for such environmental factors when establishing patterns of molt. The April-hatched turkeys in this experiment subjected to natural light conditions showed more molting at a given age than did those described by Payne (1947) which were hatched in May. The present results, as best demonstrated by the data presented in Figure 4, show that the ultimate number of feathers molted in the juvenile and postjuvenile plumage is conditioned by light variaations. It is possible that this factor influenced to some extent the results reported by Leopold (1943), who stated that domestic turkeys retained only the distal juvenile primary; while the two distal primaries were not replaced in M. G. syhestris, a wild turkey. The distal
juvenile primary is also retained during the first laying year in many chickens, according to Marble (1934) and Warren and Gordon (1935). It is felt that variations in length of day probably account for the fact that early-hatched poults do not show a proper finish of feathers before the short days of winter. The present data lend no support to the belief held by many that cold weather is required to produce turkeys free of pinfeathers. SUMMARY
Restriction of light to 12 hours daily from 4 to 16 weeks of age and to 10 hours daily from 17 to 28 weeks of age resulted in reduced molting of the first postjuvenile plumage in turkeys. When such turkeys were dressed, fewer pinfeathers were noted than were present for birds of the same age and origin reared under natural daylight or for those provided 15 hours of light daily. Classification scores for degree of molting in wing primaries and in body feathers of the femoral tract were associated with scores of the dressed appearance. Temperature variations within the range from 44° to 70°F. had no apparent influence on molting. Turkeys reared under the restricted light conditions were relatively free of pinfeathers at 24 weeks of age. Such birds when dressed on October 20 at 28 weeks of age exhibited an appearance comparable to that normally expected a month later in turkeys reared under natural light. REFERENCES Bissonnette, T. H., 193S. Relations of hair cycles in ferrets to changes in the anterior hypophysis and to light cycles. Anat. Rec. 63: 159-168. Bissonnette, T. H., and E. Wilson, 1939. Shortening daylight periods between May IS and September 12 and the pelt cycle of the mink. Science 89: 418HU9.
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of light rather than the length of day would be a factor. Ordinarily, artificial light of reasonable candle power is a satisfactory substitute for sunlight in rearing poultry when adequate rations are employed. It is a well known fact that increased light stimulates reproductive activity in many species of birds. It has been shown by Warren et al. (1950) and by Mueller et al. (1951) that increased light inhibits or suppresses the normal progress of the annual molt following a season of egg production in the domestic fowl, and that temperature variations have a minor effect on that molt. It would seem that the molts which precede sexual maturity, as studied in the present experiment, must be regulated by different physiological processes because the inhibitory effect on molt was produced by restricting the light. The molt preceding sexual maturity and the fur cycles of some animals apparently are affected in a similar fashion by variations in light.
837
838
ASSOCIATION NOTES
Host, P., 1942. Effect of light on the moults and sequences of plumage in the Willow Ptarmigan. Auk 59: 388-403. Leopold, A. S., 1943. The molts of young wild and domestic turkeys. Condor 45: 133-145. Marble, D. R., 1934. Relation of juvenile plumage to growth and sexual maturity. Poultry Sci. 13: 195-201. Mueller, C. D., T. B. Avery, H. D. Smith and R. E. Clegg, 1951. Effects of controlled light and temperature for laying hens. Poultry Sci. 30:679-686.
Payne, L. F., 1947. Frequency of the tail and wing molt in turkeys. Poultry Sci. 26: 52-60. Warren, D. C , R. Conrad, A. E. Schumacher and T. B. Avery, 1950. Effects of fluctuating environment on laying hens. Kansas Agr. Expt. Sta. Tech. Bui. 68. Warren, D. C , and C. D. Gordon, 1935. The sequence of appearance, molt, and replacement of the juvenile remiges of some domestic birds. J. Agr. Res. 51:459-470. Winn, H. S., 1951. Personal communication.
{Continued from page 8ZS)
He is a member of the Poultry Science Association, the American Chemical Society, Society for Experimental Biology and Medicine, American Association for the Advancement of Science, Texas Academy of Science, American Institute of Nutrition, Federated Societies of Biology, Sigma Xi and Gamma Alpha. POULTRY SCIENCE RESEARCH PRIZE
W. E. BRILES
Winner of the Poultry Science Research Prize
tural and Mechanical College and Texas Agricultural Experiment Station as Professor of Poultry Husbandry and Biochemistry and Nutrition.
The Poultry Science Association's Research Prize of one hundred dollars for the outstanding research paper published during the preceding year was presented to Dr. W. E. Briles, Department of Poultry Husbandry, Texas Agricultural and Mechanical College System, College Station, Texas. The prize was awarded for his studies at the University of Wisconsin in collaboration with W. H. McGibbon and M. R. Irwin. The paper was entitled, "On Multiple Alleles Effecting Cellular Antigens in the Chicken," and was published iriGenetics 35: 633-652, 1950. Worthie Elwood Briles was born January 31, 1918 at Italy, Texas. He graduated from Polytechnic High School, Fort Worth, Texas, in 1936 and attended North Texas Agricultural College, Arling-
(Continued on page 85S)
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Association Notes