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Increasing Egg Production in Winter-Hatched Turkeys by a Restricted Light Treatment
46
W. B. GROSS AND G. COLMANO SUMMARY
Social stress induced resistance to air sac or intravenous challenge with pathogenic strains of Escherichia coli could be produced by mixing socially unrelated cockerels for a short a time as 1 day. Resistance decreased with increasing time between social mixing and challenge. Resistance could not be correlated with preinoculation values for relative numbers of various heterophile series cell types; circulating heterophiles; weight grain, pecks given or received. Resistance could be partially correlated with increased levels of corticosteroids in the plasma. REFERENCES Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Gross, W. B., and H. S. Siegel, 1965. The effects of social stress on resistance to infection with Escherichia coli or Mycoplasma gallisepticum. Poultry Sci. 44: 998-1001. Guilemin, R., G. W. Clayton, H. S. Lipscome and J. D. Smith, 1959. Fluorometric measurement of rat plasma and adrenal corticosterone concentration. J. Lab. Clin. Med. S3: 830-832. Siegel, H. S., and W. B. Gross, 1965. Social grouping, stress and resistance to coliform infection in cockerels. Poultry Sci. 44: 1530-1536.
Increasing Egg Production in Winter-Hatched Turkeys by a Restricted Light Treatment W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD University of California, Davis 95616 (Received for publication May 14, 1966)
SHORT daily light restriction given to fall or early-winter-hatched turkeys prior to maturity will, by virtue of disrupting hypothalamic refractoriness to
A
Supported in part from a grant from the California Committee on Relation of Electricity to Agriculture.
seasonal increases in day light, decrease age at first egg and improve rate of lay (Marr et al., 1956; Harper and Parker, 1957). More recent investigations indicate that successful light restriction programs are dependent upon four factors: 1) length of the daily light period; 2) duration of the imposed daily light restriction; 3) age of
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
those that were not handled. There was no social stress induced resistance or social interaction as manifested by pecking when paired groups of males were moved among females. Some social interaction and pecking occurred among the controls which were more resistant than cockerels that were raised in visual and physical isolation from other birds. Social stress induced resistance can probably be greatly reduced in experiments by maintaining birds as closed social groups for at least a week before the onset of the experimental procedures. Resistance could not be correlated with preinoculation values such as: relative numbers of various heterophile series cells in bone marrow; numbers of circulating heterophiles: weight gain; pecks received or given; pecking activity or peck order. Resistance did seem to be correlated with relatively high levels of plasma corticosteroids. This is further strengthened by the increased resistance and increased plasma corticosteroids following the continuous I.V. administration of corticotropin.
LIGHT AND EGG PRODUCTION
One purpose of this study was to determine if the extension of the light restriction period to include the entire growing period, thus simulating the conditions under which spring-hatched poults are reared, would improve rate of lay of winter-hatched birds
over a 24-week production period. In a second test, mature and immature Bronze hens exposed to a light treatment of 6 hours per day for a period of 5 weeks were studied. METHODS AND PROCEDURES Winter-hatched Broad Breasted Bronze turkeys, University of California strain were used in all experiments. The term daily light restriction as used in the text refers to a period of 6 hours light and 18 hours darkness per day. Control lighting means 14 hours of light and 10 hours of darkness per day. In Tests 1 and 2, which were replicates, females were brooded under 14-hour light day until 8 weeks of age, at which time they were assigned at random to one of four groups and given one of the following treatments. Treatment 1 (group A): Six hours of light daily to 27 weeks of age in a temperature- and light-controlled chamber; 14 hours of daily light thereafter. Treatment 2 (group B): Six hours of light daily to 31 weeks of age in a temperature- and light-controlled chamber; 14 hours light daily thereafter. Treatment 3 (group C): Natural daylight to 27 weeks of age in range pens; 6 hours of light per day from 27 to 31 weeks of age, and 14 hours light daily thereafter. Treatment 4 (group D): Natural daylight to 31 weeks of age in range pens; 14 hours light daily thereafter. Criteria measured were: age in weeks at first egg; number of nonlaying hens; body weight and egg production of individual hens. In Test 3, three age groups of Decemberhatched BBB females were held in range pens, under natural daylight conditions, until approximately 35 percent of the birds had reached sexual maturity. At that time
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the females at time of light restriction; and 4) total daily hours of stimulatory light and method of application. Light restriction programs involving the application of one or more of the above factors have been studied by Asmundson and Moses (1950), Marr et al. (1956), Harper and Parker (1957), Ogasawara et al. (1962), McCartney et al. (1961), Leighton et al. (1961a, b), Wilson et al. (1962), and Marsden and Lucas (1964). On the basis of their results, it is evident that daily light restrictions of short duration impose critical limits on the age when females can be successfully given short daily light restriction followed by an increase in daily light. An increase in daily light given to Broad Breasted Bronze females, following light restriction, at 22 or 24 weeks of age, resulted in failure of many birds to reach sexual maturity during a subsequent 19-week laying period, Wilson et al. (1962). The upper critical age limit at which an increase in total hours of daily light may be successfully imposed on Bronze females has not been established. However, the duration of the short daily light restriction should extend beyond the age of 26 to 28 weeks, the age at which some females reach maturity. It makes little difference, according to Ogasawara et al. (1962), and Leighton et al. (1961a) whether the increase in daily light following light restriction is abrupt or whether light is gradually increased from 14 to 20 hours per day during the laying period. Most investigators agree that offseason egg production from fall-hatched turkeys is not as high as that from springhatched hens.
47
48
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD TABLE 1.—Effect
Group A B C D
Housed Housed Ranged Ranged
of restricted photoperiod on median age of 1st egg and on number of non-layers {Broad Breasted Bronze turkeys)
Light treatment and duration in weeks 6 hr. light: 8 to 27 6 hr. light: 8 to 31 Natural daylight: 8 to 27 Natural daylight: 8 to 31
Median age at 1st egg (days) Test 1 215 242 248 302
Ratio of non-layers to layers
Test 2
Test 1
Test 2
210 243 249 300
0/7 1/47 0/49 2/9
0/11 0/46 1/44 0/11
Natural daylight range: 9 to 15 hr. Birds in all groups were given 14 hours of light daily until 8 weeks of age.
RESULTS Tests 1 and 2: Light restriction. Median age at first egg and number of birds in each treatment failing to attain sexual maturity are given in Table 1. Birds that received restricted light during the growing period reached sexual maturity earlier than did comparable birds kept in range pens during the growing period. Hens reared continuously under conditions of natural increasing daylight, even though given 14 hours light daily starting at 31 weeks of age, reached maturity approximately 50 days later than did hens reared under sim-
ilar conditions but which received restricted light during the period 27 to 31 weeks of age. The delay in sexual maturity of hens not previously preconditioned by restricted daily light perhaps is a result of hypothalamic-hypophyseal refractoriness to seasonal increases in natural daylight. Average body weight of range-reared female (groups C and D) at 24 and 44 weeks of age was 5843 ± 41 and 7606 ± 77 grams as compared to 5239 ± 139 and 6747 ± 69 grams for females kept in temperature- and light-controlled pens. This difference in body weight was highly significant. Average egg weights of the rangereared and the light-chamber-reared birds were 82.6 and 81.3 grams respectively. This difference was not significant. Total number of eggs laid in each of the four treatment groups is given in Figures 1 and 2. Birds receiving restricted light during the adolescent period (groups A and B) laid more eggs than did comparable hens reared under conditions of natural daylight (groups C and D). Light-restricted hens (group A) given 14 hours daily light at 27 weeks of age reached maturity approximately 30 days earlier than did similar preconditioned females given 14 hours of light daily at 31 weeks of age (group B). However, the birds in the latter group laid more eggs during the 2 4-week period following stimulighting. Nonlight-restricted birds (group D) laid the majority of their eggs during the second 12-week period of pro-
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the hens, then 29, 30, and 31 weeks of age, respectively, were placed in individual cages within a darkened house with walls covered with 6-mil black polyethylene. Evaporative coolers were used to maintain a favorable temperature. The hens received 6 hours of light per day for 5 weeks. At the start of the short day period the condition of the oviduct orifice was determined. Based on the findings, the hens were classified as (a) immature females with no apparent oviduct development; (b) females showing some oviduct development; or (c) females in laying condition, as indicated by egg production. The oviducts of the sexually mature females were examined weekly to determine the rate of oviduct regression. Rate of regression, according to Wilson et al. (1958), is a good indicator of oviduct development in the chicken.
49
LIGHT AND EGG PRODUCTION
L i g h l Treolmcnt B r Q
54 n
6h.-8io3l»k Doylight-B to27»k i 6 h . for A wk Daylight - 8 to 31 wk
.S
.
1
Light Treatment 0 h r - 8 to 27 - k * h . - 8ro 31 wk Poylight - 8 to 27 wk & 6 hr tar i wk Doyl.ghr - 8 to 31 wk
20
22
24
FIG. 2. Cumulative frequency curve of total eggs laid per B.B. Bronze turkeys following termination of the light restriction and subsequent exposure to 14 hours of light per day. Test 2.
and to first egg following the restricted light period are given in Table 2. Considerable individual variation in rate of oviduct regression was noted. Numbers of eggs per hen laid during the restricted light period varied from 1 to 18. Egg production dropped from 58.8 percent during the first week of light restriction to 5.0 and 0.8 percent for the second and third weeks, respectively. Average time to termination of lay was approximately 7 days following initiation of the restricted light period. These A Q -Q Q
Light Treatment 6 k , - 8 to 27 - k 6 hr - 8 to 31 wk Daylight - 8 to 27 wk & 6 hr for Daylight - 8 to 31 - k
^*""
^
/ s s/ // */
S s'
_,-*"
^ ^ • • ' ^ S** ^ S h 2 S ***' * ^
-A B C D—
'z = ^ / r
, _ I . - I - I
,
1
,
1
.
1
,
1
,
1
,
1
12 WEEKS
FIG. 1. Cumulative frequency curve of total eggs laid per B.B. Bronze turkeys following termination of the light restriction and subsequent exposure to 14 hours of light per day. Test 1.
FIG. 3. Effect of daily light restriction (6 hours/ day), imposed at different ages of development, on percent egg production by Bronze turkeys during a 24-week period immediately following treatment. Test 2.
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duction (Figure 3). Similar results were reported by Leighton and Shoffner (1961), who found that hens not previously conditioned by a short light restriction laid at a lower rate during the first 3 months of production, but at a higher rate during the winter months, than did birds that had been preconditioned by a light restriction. Some range-reared birds in both groups C and D reached maturity prior to housing time. Presumably the move from range pens to individual cages may have contributed, to some extent, to the lower age at sexual maturity. Also the daily light restriction given at 27 weeks of age may have been a factor in the delaying of maturity in hens in group C. Test 3: Effect of light restriction on reproduction in mature and immature females. The 6-hour daily light restriction treatment caused all sexually mature females to terminate egg production. Each mature female was everted at the end of the S-week light restriction period and, on the basis of oviduct development, classified into one of two groups. These were: (D) hens easily everted, with enlargement of the oviduct orifice indicated and (U) hens not easily everted and with small undeveloped oviduct orifices. Comparisons of the average number of days to terminal egg
50
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD TABLE 2.—Average number of days to lay and rate of lay of Broad Breasted Bronze following period of restricted light
No. of Hatch mature hens
1 2 3
33 9 6
31 30 29
Condition of oviduct of mature hens at end of short-day treatment
Mature hens returning to production following treatment
Average no. of days to terminal egg during treatment
Average number of days to 1st egg following treatment
D
U
No.
Percent
D
U
D
U
11 3 1
22 6 5
24 6 5
77.4 66.6 83.3
8.6 14.0 1.0
6.4 5.0 5.0
31.7 26.0 25.0
36.2 32.2 32.2
15
33
9.1
5.9
27.9
34.8
D = Female easily everted and oviduct orifice enlarged. U=Female not easily everted and oviduct orifice small.
findings are in agreement with those of Leighton and Shoffner (1964), who reported that a light restriction of 6 hours per day given to mature females in their sixth month of lay resulted in cessation of production within 7 days and subsequently complete molt. In our studies, birds with indication of some oviduct development at the end of the S-week light restriction period laid approximately 7 days earlier than did mature birds with small undeveloped oviduct orifices. DISCUSSION
Our data indicate that a preconditioning program given to winter-hatched Bronze females for purposes of providing off-season egg production must fulfill two related physiological requirements. These are: 1) attainment of maximum body growth of the bird before the total hours of daily light is increased, and 2) delay of sexual maturity until maximum gonadal development is assured. These requirements are substantiated by a comparison in age at first egg and subsequent rate of lay between birds in groups A and B. These birds were given 6 hours of light daily starting at 27 weeks of age, reached a peak of 55 percent production, thereafter, rate of
lay decreased abruptly (Figure 3). A similar production curve is obtained when females are given increased increments of daily light at too early an age, or are not adequately preconditioned by short-day light treatment. Hens preconditioned by the short-day treatment until 31 weeks of age and then given 14 hours of daily light (group B) reached a peak of 70 percent production and laid more eggs within the 24-week laying period than hens in group A (Figure 3). Had birds in group B been allowed a period of production equivalent in time to that of the 27-week old females, the difference in total eggs laid would have been even greater. Leighton and Shoffner (1961b) reported that, within an extended period of production, total number of eggs is approximately the same irrespective of prelay treatment of the hens. In our study, it is doubtful whether an extension of the 24-week period of lay would have resulted in more comparable rates of lay between birds in groups A and B. In Test 3, all mature birds in the 29-week age group, after receiving a light restriction of 6 hours per day for 5 weeks, returned to egg production within a 10-week period following the increase to 14 hours of daily light (Table 3). Approxi-
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51
Age at start of short day (weeks)
51
LIGHT AND EGG PRODUCTION TABLE 3.—Percent of females reaching maturity after short day treatment and average number of eggs laid per group for 10-week period
Hatch
1 2 3
Age in weeks
31 30 29
Total birds
78 46 12
Percent females in each class*
Percent females laying after treatment
Av. number of days to first egg following light restriction
A
B
A
C
A
B
57.9 85.7 50.0
7.3
72.7 66.7 83.3
30.0 28.9 27.0
32.0
C
B
34.8 97.5 80.0 14.3 97.3 50.0 100.0
C
Number of eggs/ bird laid in 10-week period following light restriction A
34.8 26.8 30.1 28.8 31.0 28.0
B 23.5
C 24.3 26.7 22.7
mately 25% of all mature birds, when given short-day light treatment, failed to return to production within the 10-week period following 14 hours of daily light. All mature females exposed to a 5-week light restriction of 6 hours per day dropped out of production within 7 days. A similar response was reported by Leighton and Shoffner (1964). They found that yearling Bronze females which had completed 6 months of lay when subjected either to a 3 or a 5-week restriction period, went out of production within 7 days. However, these authors reported that cessation of production was accompanied by a complete molt. In contrast, the younger mature Bronze females in our study did not molt following cessation of lay. Many females at the end of the 5-week light restriction showed some oviducal development. This contrast in response by mature females of different ages to restricted light may best be explained by the results of Burger (1957). He reported that the degree of gonadal response in starlings is mainly dependent upon the duration of the activating stimulus (long light day). SUMMARY
Winter-hatched Broad Breasted Bronze turkeys were subjected to various light treatments. In two duplicate tests, hens
were exposed to 6 hours light, starting when they were either 8 or 27 weeks of age. Comparisons were made of age at first egg and subsequent egg production over a 24-week period. Best egg production was attained from hens exposed to 6 hours of light daily, starting at 8 and continuing to 31 weeks of age, before receiving 14 hours light. Females given 14 hours of light per day after being exposed to 6 hours light daily restriction from 8 to 27 weeks of age, reached maturity earlier than did comparable hens in other treatments. However, these birds did not maintain a favorable rate of lay. The implication is that the hens had not completed their growth by 27 weeks of age. Two groups of birds reared under conditions of natural daylight until 27 weeks of age, one group then receiving 6 hours light daily from 27 to 31 weeks, the other remaining under natural daylight to 31 weeks of age, laid fewer eggs than did birds receiving 6 hours light from 8 to 27 weeks of age. Exposing young mature birds, to a restricted light program of 6 hours light per day for 5 weeks caused a cessation in lay. Following the end of the restricted light period 25% of the birds remained out of production during a 10-week test period.
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* A=immature females. B=females with some oviducal development. C = mature females (laid 1 or more eggs).
52
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD and H. L. Wilcke, 1956. Effect of controlled light during the growing period upon subsequent performance of breeder turkeys. Poultry Sci. 35: 1156. Marsden, S. J., and L. M. Lucas, 1964. Effect of short day or low-intensity light treatments on reproduction of fall-hatched turkeys in two environments. Poultry Sci. 43 : 434-441. McCartney, M. G., V. L. Sanger, K. I. Brown and V. D. Chamberlin, 1961. Photoperiodism as a factor in the reproduction of the turkey. Poultry Sci. 40: 368-376. Ogasawara, F. X., W. O. Wilson and V. S. Asmundson, 1962. The effect of restricting light during the adolescent period on reproductive performance in turkeys subsequently exposed to a 12-, 14-, and 20-hour day. Poultry Sci. 4 1 : 1858-1863. Wilson, W. O., F. X. Ogasawara and V. S. Asmundson, 1962. Artificial control of egg production in turkeys by photoperiods. Poultry Sci. 40: 1168-1175. Wilson, W. O., A. E. Woodard, J. O. Nordstrom and A. H. Smith, 1958. Regressive changes in external indicators of laying condition following cessation of laying. Poultry Sci. 37: 24-26.
Pre-laying Nutritional and Environmental Factors in the Performance of the Adult Fowl 2. INFLUENCE OF ENVIRONMENT ON THE CALCIUM REQUIREMENT AND ADAPTATION OF SINGLE COMB WHITE LEGHORN FEMALES D. L. ANDERSON Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01002 (Received for publication May 21, 1966)
F
ACTORS affecting the calcium and/or phosphorus requirements of the growing chicken female from 8-18 weeks for "normal" development and maximum productive performance and body maintenance during the first egg laying cycle have been given inadequate consideration. Of the numerous pre-laying factors, Contribution from the Massachusetts Agricultural Experiment Station, Amherst, Massachusetts.
known or unknown, that may possibly contribute to the variation in response of production bred stock, differences in nutrient intake ("inadequate," "adequate" or "excessive") and environmental conditions (housing, temperature, lighting, etc.) are of universal importance. It has been demonstrated that restricting the level of total feed intake during the growing period resulted in delayed sexual
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
REFERENCES Asmundson, V. S., and B. D. Moses, 1950. Influence of length of day on reproduction in turkey hens. Poultry Sci. 29 : 34-41. Burger, J. W., 1947. On the relation of day length to the phases of testicular involution and inactivity of the spermatogenetic cycle of the Starling. Exp. Zool. 105: 259-267. Harper, J. A., and J. E. Parker, 1957. Changes in seasonal egg production of turkeys induced through controlled light exposure and force moulting. Poultry Sci. 36: 967-973. Leighton, A. T., Jr., and R. N. Shoffner, 1961a. Effect of light regime and age on reproduction of turkeys. 1. Effect of 15, 24 hour, and restricted light treatment. Poultry Sci. 40: 861870. Leighton, A. T., Jr., and R. N. Shoffner, 1961b. Effect of light regime and age on the production of turkeys. 2. Restricted vs. unrestricted light. Poultry Sci. 40: 871-884. Leighton, A. T., Jr., and R. N. Shoffner, 1964. Effect of light regime and age on reproduction of turkeys. 3. Restricted light on yearling hens. Poultry Sci. 43 : 49-53. Marr, J. E., F. W. Garland, Jr., J. L. Milligan
W. B. GROSS AND G. COLMANO SUMMARY
Social stress induced resistance to air sac or intravenous challenge with pathogenic strains of Escherichia coli could be produced by mixing socially unrelated cockerels for a short a time as 1 day. Resistance decreased with increasing time between social mixing and challenge. Resistance could not be correlated with preinoculation values for relative numbers of various heterophile series cell types; circulating heterophiles; weight grain, pecks given or received. Resistance could be partially correlated with increased levels of corticosteroids in the plasma. REFERENCES Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Gross, W. B., and H. S. Siegel, 1965. The effects of social stress on resistance to infection with Escherichia coli or Mycoplasma gallisepticum. Poultry Sci. 44: 998-1001. Guilemin, R., G. W. Clayton, H. S. Lipscome and J. D. Smith, 1959. Fluorometric measurement of rat plasma and adrenal corticosterone concentration. J. Lab. Clin. Med. S3: 830-832. Siegel, H. S., and W. B. Gross, 1965. Social grouping, stress and resistance to coliform infection in cockerels. Poultry Sci. 44: 1530-1536.
Increasing Egg Production in Winter-Hatched Turkeys by a Restricted Light Treatment W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD University of California, Davis 95616 (Received for publication May 14, 1966)
SHORT daily light restriction given to fall or early-winter-hatched turkeys prior to maturity will, by virtue of disrupting hypothalamic refractoriness to
A
Supported in part from a grant from the California Committee on Relation of Electricity to Agriculture.
seasonal increases in day light, decrease age at first egg and improve rate of lay (Marr et al., 1956; Harper and Parker, 1957). More recent investigations indicate that successful light restriction programs are dependent upon four factors: 1) length of the daily light period; 2) duration of the imposed daily light restriction; 3) age of
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
those that were not handled. There was no social stress induced resistance or social interaction as manifested by pecking when paired groups of males were moved among females. Some social interaction and pecking occurred among the controls which were more resistant than cockerels that were raised in visual and physical isolation from other birds. Social stress induced resistance can probably be greatly reduced in experiments by maintaining birds as closed social groups for at least a week before the onset of the experimental procedures. Resistance could not be correlated with preinoculation values such as: relative numbers of various heterophile series cells in bone marrow; numbers of circulating heterophiles: weight gain; pecks received or given; pecking activity or peck order. Resistance did seem to be correlated with relatively high levels of plasma corticosteroids. This is further strengthened by the increased resistance and increased plasma corticosteroids following the continuous I.V. administration of corticotropin.
LIGHT AND EGG PRODUCTION
One purpose of this study was to determine if the extension of the light restriction period to include the entire growing period, thus simulating the conditions under which spring-hatched poults are reared, would improve rate of lay of winter-hatched birds
over a 24-week production period. In a second test, mature and immature Bronze hens exposed to a light treatment of 6 hours per day for a period of 5 weeks were studied. METHODS AND PROCEDURES Winter-hatched Broad Breasted Bronze turkeys, University of California strain were used in all experiments. The term daily light restriction as used in the text refers to a period of 6 hours light and 18 hours darkness per day. Control lighting means 14 hours of light and 10 hours of darkness per day. In Tests 1 and 2, which were replicates, females were brooded under 14-hour light day until 8 weeks of age, at which time they were assigned at random to one of four groups and given one of the following treatments. Treatment 1 (group A): Six hours of light daily to 27 weeks of age in a temperature- and light-controlled chamber; 14 hours of daily light thereafter. Treatment 2 (group B): Six hours of light daily to 31 weeks of age in a temperature- and light-controlled chamber; 14 hours light daily thereafter. Treatment 3 (group C): Natural daylight to 27 weeks of age in range pens; 6 hours of light per day from 27 to 31 weeks of age, and 14 hours light daily thereafter. Treatment 4 (group D): Natural daylight to 31 weeks of age in range pens; 14 hours light daily thereafter. Criteria measured were: age in weeks at first egg; number of nonlaying hens; body weight and egg production of individual hens. In Test 3, three age groups of Decemberhatched BBB females were held in range pens, under natural daylight conditions, until approximately 35 percent of the birds had reached sexual maturity. At that time
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
the females at time of light restriction; and 4) total daily hours of stimulatory light and method of application. Light restriction programs involving the application of one or more of the above factors have been studied by Asmundson and Moses (1950), Marr et al. (1956), Harper and Parker (1957), Ogasawara et al. (1962), McCartney et al. (1961), Leighton et al. (1961a, b), Wilson et al. (1962), and Marsden and Lucas (1964). On the basis of their results, it is evident that daily light restrictions of short duration impose critical limits on the age when females can be successfully given short daily light restriction followed by an increase in daily light. An increase in daily light given to Broad Breasted Bronze females, following light restriction, at 22 or 24 weeks of age, resulted in failure of many birds to reach sexual maturity during a subsequent 19-week laying period, Wilson et al. (1962). The upper critical age limit at which an increase in total hours of daily light may be successfully imposed on Bronze females has not been established. However, the duration of the short daily light restriction should extend beyond the age of 26 to 28 weeks, the age at which some females reach maturity. It makes little difference, according to Ogasawara et al. (1962), and Leighton et al. (1961a) whether the increase in daily light following light restriction is abrupt or whether light is gradually increased from 14 to 20 hours per day during the laying period. Most investigators agree that offseason egg production from fall-hatched turkeys is not as high as that from springhatched hens.
47
48
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD TABLE 1.—Effect
Group A B C D
Housed Housed Ranged Ranged
of restricted photoperiod on median age of 1st egg and on number of non-layers {Broad Breasted Bronze turkeys)
Light treatment and duration in weeks 6 hr. light: 8 to 27 6 hr. light: 8 to 31 Natural daylight: 8 to 27 Natural daylight: 8 to 31
Median age at 1st egg (days) Test 1 215 242 248 302
Ratio of non-layers to layers
Test 2
Test 1
Test 2
210 243 249 300
0/7 1/47 0/49 2/9
0/11 0/46 1/44 0/11
Natural daylight range: 9 to 15 hr. Birds in all groups were given 14 hours of light daily until 8 weeks of age.
RESULTS Tests 1 and 2: Light restriction. Median age at first egg and number of birds in each treatment failing to attain sexual maturity are given in Table 1. Birds that received restricted light during the growing period reached sexual maturity earlier than did comparable birds kept in range pens during the growing period. Hens reared continuously under conditions of natural increasing daylight, even though given 14 hours light daily starting at 31 weeks of age, reached maturity approximately 50 days later than did hens reared under sim-
ilar conditions but which received restricted light during the period 27 to 31 weeks of age. The delay in sexual maturity of hens not previously preconditioned by restricted daily light perhaps is a result of hypothalamic-hypophyseal refractoriness to seasonal increases in natural daylight. Average body weight of range-reared female (groups C and D) at 24 and 44 weeks of age was 5843 ± 41 and 7606 ± 77 grams as compared to 5239 ± 139 and 6747 ± 69 grams for females kept in temperature- and light-controlled pens. This difference in body weight was highly significant. Average egg weights of the rangereared and the light-chamber-reared birds were 82.6 and 81.3 grams respectively. This difference was not significant. Total number of eggs laid in each of the four treatment groups is given in Figures 1 and 2. Birds receiving restricted light during the adolescent period (groups A and B) laid more eggs than did comparable hens reared under conditions of natural daylight (groups C and D). Light-restricted hens (group A) given 14 hours daily light at 27 weeks of age reached maturity approximately 30 days earlier than did similar preconditioned females given 14 hours of light daily at 31 weeks of age (group B). However, the birds in the latter group laid more eggs during the 2 4-week period following stimulighting. Nonlight-restricted birds (group D) laid the majority of their eggs during the second 12-week period of pro-
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
the hens, then 29, 30, and 31 weeks of age, respectively, were placed in individual cages within a darkened house with walls covered with 6-mil black polyethylene. Evaporative coolers were used to maintain a favorable temperature. The hens received 6 hours of light per day for 5 weeks. At the start of the short day period the condition of the oviduct orifice was determined. Based on the findings, the hens were classified as (a) immature females with no apparent oviduct development; (b) females showing some oviduct development; or (c) females in laying condition, as indicated by egg production. The oviducts of the sexually mature females were examined weekly to determine the rate of oviduct regression. Rate of regression, according to Wilson et al. (1958), is a good indicator of oviduct development in the chicken.
49
LIGHT AND EGG PRODUCTION
L i g h l Treolmcnt B r Q
54 n
6h.-8io3l»k Doylight-B to27»k i 6 h . for A wk Daylight - 8 to 31 wk
.S
.
1
Light Treatment 0 h r - 8 to 27 - k * h . - 8ro 31 wk Poylight - 8 to 27 wk & 6 hr tar i wk Doyl.ghr - 8 to 31 wk
20
22
24
FIG. 2. Cumulative frequency curve of total eggs laid per B.B. Bronze turkeys following termination of the light restriction and subsequent exposure to 14 hours of light per day. Test 2.
and to first egg following the restricted light period are given in Table 2. Considerable individual variation in rate of oviduct regression was noted. Numbers of eggs per hen laid during the restricted light period varied from 1 to 18. Egg production dropped from 58.8 percent during the first week of light restriction to 5.0 and 0.8 percent for the second and third weeks, respectively. Average time to termination of lay was approximately 7 days following initiation of the restricted light period. These A Q -Q Q
Light Treatment 6 k , - 8 to 27 - k 6 hr - 8 to 31 wk Daylight - 8 to 27 wk & 6 hr for Daylight - 8 to 31 - k
^*""
^
/ s s/ // */
S s'
_,-*"
^ ^ • • ' ^ S** ^ S h 2 S ***' * ^
-A B C D—
'z = ^ / r
, _ I . - I - I
,
1
,
1
.
1
,
1
,
1
,
1
12 WEEKS
FIG. 1. Cumulative frequency curve of total eggs laid per B.B. Bronze turkeys following termination of the light restriction and subsequent exposure to 14 hours of light per day. Test 1.
FIG. 3. Effect of daily light restriction (6 hours/ day), imposed at different ages of development, on percent egg production by Bronze turkeys during a 24-week period immediately following treatment. Test 2.
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duction (Figure 3). Similar results were reported by Leighton and Shoffner (1961), who found that hens not previously conditioned by a short light restriction laid at a lower rate during the first 3 months of production, but at a higher rate during the winter months, than did birds that had been preconditioned by a light restriction. Some range-reared birds in both groups C and D reached maturity prior to housing time. Presumably the move from range pens to individual cages may have contributed, to some extent, to the lower age at sexual maturity. Also the daily light restriction given at 27 weeks of age may have been a factor in the delaying of maturity in hens in group C. Test 3: Effect of light restriction on reproduction in mature and immature females. The 6-hour daily light restriction treatment caused all sexually mature females to terminate egg production. Each mature female was everted at the end of the S-week light restriction period and, on the basis of oviduct development, classified into one of two groups. These were: (D) hens easily everted, with enlargement of the oviduct orifice indicated and (U) hens not easily everted and with small undeveloped oviduct orifices. Comparisons of the average number of days to terminal egg
50
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD TABLE 2.—Average number of days to lay and rate of lay of Broad Breasted Bronze following period of restricted light
No. of Hatch mature hens
1 2 3
33 9 6
31 30 29
Condition of oviduct of mature hens at end of short-day treatment
Mature hens returning to production following treatment
Average no. of days to terminal egg during treatment
Average number of days to 1st egg following treatment
D
U
No.
Percent
D
U
D
U
11 3 1
22 6 5
24 6 5
77.4 66.6 83.3
8.6 14.0 1.0
6.4 5.0 5.0
31.7 26.0 25.0
36.2 32.2 32.2
15
33
9.1
5.9
27.9
34.8
D = Female easily everted and oviduct orifice enlarged. U=Female not easily everted and oviduct orifice small.
findings are in agreement with those of Leighton and Shoffner (1964), who reported that a light restriction of 6 hours per day given to mature females in their sixth month of lay resulted in cessation of production within 7 days and subsequently complete molt. In our studies, birds with indication of some oviduct development at the end of the S-week light restriction period laid approximately 7 days earlier than did mature birds with small undeveloped oviduct orifices. DISCUSSION
Our data indicate that a preconditioning program given to winter-hatched Bronze females for purposes of providing off-season egg production must fulfill two related physiological requirements. These are: 1) attainment of maximum body growth of the bird before the total hours of daily light is increased, and 2) delay of sexual maturity until maximum gonadal development is assured. These requirements are substantiated by a comparison in age at first egg and subsequent rate of lay between birds in groups A and B. These birds were given 6 hours of light daily starting at 27 weeks of age, reached a peak of 55 percent production, thereafter, rate of
lay decreased abruptly (Figure 3). A similar production curve is obtained when females are given increased increments of daily light at too early an age, or are not adequately preconditioned by short-day light treatment. Hens preconditioned by the short-day treatment until 31 weeks of age and then given 14 hours of daily light (group B) reached a peak of 70 percent production and laid more eggs within the 24-week laying period than hens in group A (Figure 3). Had birds in group B been allowed a period of production equivalent in time to that of the 27-week old females, the difference in total eggs laid would have been even greater. Leighton and Shoffner (1961b) reported that, within an extended period of production, total number of eggs is approximately the same irrespective of prelay treatment of the hens. In our study, it is doubtful whether an extension of the 24-week period of lay would have resulted in more comparable rates of lay between birds in groups A and B. In Test 3, all mature birds in the 29-week age group, after receiving a light restriction of 6 hours per day for 5 weeks, returned to egg production within a 10-week period following the increase to 14 hours of daily light (Table 3). Approxi-
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51
Age at start of short day (weeks)
51
LIGHT AND EGG PRODUCTION TABLE 3.—Percent of females reaching maturity after short day treatment and average number of eggs laid per group for 10-week period
Hatch
1 2 3
Age in weeks
31 30 29
Total birds
78 46 12
Percent females in each class*
Percent females laying after treatment
Av. number of days to first egg following light restriction
A
B
A
C
A
B
57.9 85.7 50.0
7.3
72.7 66.7 83.3
30.0 28.9 27.0
32.0
C
B
34.8 97.5 80.0 14.3 97.3 50.0 100.0
C
Number of eggs/ bird laid in 10-week period following light restriction A
34.8 26.8 30.1 28.8 31.0 28.0
B 23.5
C 24.3 26.7 22.7
mately 25% of all mature birds, when given short-day light treatment, failed to return to production within the 10-week period following 14 hours of daily light. All mature females exposed to a 5-week light restriction of 6 hours per day dropped out of production within 7 days. A similar response was reported by Leighton and Shoffner (1964). They found that yearling Bronze females which had completed 6 months of lay when subjected either to a 3 or a 5-week restriction period, went out of production within 7 days. However, these authors reported that cessation of production was accompanied by a complete molt. In contrast, the younger mature Bronze females in our study did not molt following cessation of lay. Many females at the end of the 5-week light restriction showed some oviducal development. This contrast in response by mature females of different ages to restricted light may best be explained by the results of Burger (1957). He reported that the degree of gonadal response in starlings is mainly dependent upon the duration of the activating stimulus (long light day). SUMMARY
Winter-hatched Broad Breasted Bronze turkeys were subjected to various light treatments. In two duplicate tests, hens
were exposed to 6 hours light, starting when they were either 8 or 27 weeks of age. Comparisons were made of age at first egg and subsequent egg production over a 24-week period. Best egg production was attained from hens exposed to 6 hours of light daily, starting at 8 and continuing to 31 weeks of age, before receiving 14 hours light. Females given 14 hours of light per day after being exposed to 6 hours light daily restriction from 8 to 27 weeks of age, reached maturity earlier than did comparable hens in other treatments. However, these birds did not maintain a favorable rate of lay. The implication is that the hens had not completed their growth by 27 weeks of age. Two groups of birds reared under conditions of natural daylight until 27 weeks of age, one group then receiving 6 hours light daily from 27 to 31 weeks, the other remaining under natural daylight to 31 weeks of age, laid fewer eggs than did birds receiving 6 hours light from 8 to 27 weeks of age. Exposing young mature birds, to a restricted light program of 6 hours light per day for 5 weeks caused a cessation in lay. Following the end of the restricted light period 25% of the birds remained out of production during a 10-week test period.
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* A=immature females. B=females with some oviducal development. C = mature females (laid 1 or more eggs).
52
W. O. WILSON, F. X. OGASAWARA AND A. E. WOODARD and H. L. Wilcke, 1956. Effect of controlled light during the growing period upon subsequent performance of breeder turkeys. Poultry Sci. 35: 1156. Marsden, S. J., and L. M. Lucas, 1964. Effect of short day or low-intensity light treatments on reproduction of fall-hatched turkeys in two environments. Poultry Sci. 43 : 434-441. McCartney, M. G., V. L. Sanger, K. I. Brown and V. D. Chamberlin, 1961. Photoperiodism as a factor in the reproduction of the turkey. Poultry Sci. 40: 368-376. Ogasawara, F. X., W. O. Wilson and V. S. Asmundson, 1962. The effect of restricting light during the adolescent period on reproductive performance in turkeys subsequently exposed to a 12-, 14-, and 20-hour day. Poultry Sci. 4 1 : 1858-1863. Wilson, W. O., F. X. Ogasawara and V. S. Asmundson, 1962. Artificial control of egg production in turkeys by photoperiods. Poultry Sci. 40: 1168-1175. Wilson, W. O., A. E. Woodard, J. O. Nordstrom and A. H. Smith, 1958. Regressive changes in external indicators of laying condition following cessation of laying. Poultry Sci. 37: 24-26.
Pre-laying Nutritional and Environmental Factors in the Performance of the Adult Fowl 2. INFLUENCE OF ENVIRONMENT ON THE CALCIUM REQUIREMENT AND ADAPTATION OF SINGLE COMB WHITE LEGHORN FEMALES D. L. ANDERSON Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01002 (Received for publication May 21, 1966)
F
ACTORS affecting the calcium and/or phosphorus requirements of the growing chicken female from 8-18 weeks for "normal" development and maximum productive performance and body maintenance during the first egg laying cycle have been given inadequate consideration. Of the numerous pre-laying factors, Contribution from the Massachusetts Agricultural Experiment Station, Amherst, Massachusetts.
known or unknown, that may possibly contribute to the variation in response of production bred stock, differences in nutrient intake ("inadequate," "adequate" or "excessive") and environmental conditions (housing, temperature, lighting, etc.) are of universal importance. It has been demonstrated that restricting the level of total feed intake during the growing period resulted in delayed sexual
Downloaded from http://ps.oxfordjournals.org/ at University of Otago on March 12, 2015
REFERENCES Asmundson, V. S., and B. D. Moses, 1950. Influence of length of day on reproduction in turkey hens. Poultry Sci. 29 : 34-41. Burger, J. W., 1947. On the relation of day length to the phases of testicular involution and inactivity of the spermatogenetic cycle of the Starling. Exp. Zool. 105: 259-267. Harper, J. A., and J. E. Parker, 1957. Changes in seasonal egg production of turkeys induced through controlled light exposure and force moulting. Poultry Sci. 36: 967-973. Leighton, A. T., Jr., and R. N. Shoffner, 1961a. Effect of light regime and age on reproduction of turkeys. 1. Effect of 15, 24 hour, and restricted light treatment. Poultry Sci. 40: 861870. Leighton, A. T., Jr., and R. N. Shoffner, 1961b. Effect of light regime and age on the production of turkeys. 2. Restricted vs. unrestricted light. Poultry Sci. 40: 871-884. Leighton, A. T., Jr., and R. N. Shoffner, 1964. Effect of light regime and age on reproduction of turkeys. 3. Restricted light on yearling hens. Poultry Sci. 43 : 49-53. Marr, J. E., F. W. Garland, Jr., J. L. Milligan