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Effect of Ahemeral Light-Dark Cycles on Production and Egg Quality of Laying Hens12
Effect of Ahemeral Light-Dark Cycles on Production and Egg Quality of Laying Hens1'2 K. W. KOELKEBECK3 and H. V. BIELLIER Department of Animal Science, University of Missouri, Columbia, Missouri 65211 (Received for publication September 16, 1985)
1986 Poultry Science 65:874-880 INTRODUCTION A n y c o m b i n a t i o n of light and dark phases t h a t do n o t add up t o 2 4 hr have been t e r m e d " a h e m e r a l " by Morris and F o x ( 1 9 7 1 ) . Research using a light-dark cycle (LDC) shorter t h a n 24 hr has p r o d u c e d conflicting results. Woodard et al. (1962), Marks and Lucas ( 1 9 6 3 ) , and Davis et al. ( 1 9 6 4 ) e m p l o y e d LDC of 16, 18, or 2 0 hr. They f o u n d t h a t egg p r o d u c t i o n was lower for these LDC t h a n a 24-hr LDC. More recently, Yassin ( 1 9 7 8 ) r e p o r t e d t h a t a 23-hr LDC resulted in better hen-day egg p r o d u c t i o n (HDP) t h a n a 24-hr LDC w h e n applied t o an inbred flock of hens. Ahemeral LDC shorter t h a n 2 4 hr have been used mainly in selection programs, where birds which have an inherent ability t o lay at intervals less t h a n 2 4 h r can b e identified (Biellier et al, 1 9 7 8 ; Cahaner and Abplanalp, 1979).
1 Based on a portion of a thesis submitted by the senior author in partial fulfillment of the requirements for the degree of Masters of Science at the University of Missouri. a Contribution from the Missouri Agricultural Experiment Station, Journal Series Number 9977. 3 Present address: Department of Poultry Science, Texas A&M University, College Station, TX 77843.
T h e use of ahemeral LDC t h a t are longer t h a n 2 4 hr has received more a t t e n t i o n b y w o r k e r s a t t e m p t i n g to achieve b e t t e r egg quality from existing flocks (Foster, 1 9 6 9 ; Morris, 1 9 7 3 ; Leeson et al, 1 9 7 9 ; Yannak o p o u l o s and Morris, 1 9 7 9 ; N o r d s t r o m , 1 9 8 2 ; N o r d s t r o m and O u s t e r h o u t , 1983) Morris ( 1 9 7 3 ) , M e l e k et al. ( 1 9 7 3 ) , Cooper and Barnett ( 1 9 7 6 ) , and Yassin ( 1 9 7 8 ) have all s h o w n t h a t increased egg weight and shell quality can be o b t a i n e d a t t h e expense of egg n u m b e r s by using long LDC t h r o u g h o u t a laying cycle. N o r d s t r o m ( 1 9 8 2 ) and N o r d s t r o m and Ousterh o u t ( 1 9 8 3 ) d e m o n s t r a t e d t h a t exposing laying hens t o long ahemeral LDC at t h e end of their laying year w o u l d dramatically improve egg shell quality. T h e purpose of this s t u d y was t o use a long b u t decreasing light-dark cycle (LDLDC) t o increase initial pullet egg weight and shell quality, t h e n shorten this LDC t o a u g m e n t HDP. F o r comparison, a 24-hr LDC (control) and a short light-dark cycle (SLDC) t r e a t m e n t was used t h r o u g h o u t t h e laying year.
MATERIALS AND METHODS
Experimental Design. Pullets from an inbred strain of Single C o m b White Leghorn (SCWL) chickens, selected at t h e University of MissouriColumbia (UMC) for reproductive fitness in a
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ABSTRACT To compare the effects of a long but decreasing light-dark cycle (LDLDC) on egg weight and shell quality and a short light-dark cycle (SLDC) on egg production, 264 University of Missouri-Columbia (UMC) Single Comb White Leghorn (SCWL) pullets and 96 SCWL pullets from a leading commercial (C) strain were individually caged in light-controlled rooms. Treatments were: 1) 26-hr light-dark cycle (LDC) reduced to 23 hr, 2) 24-hr LDC (controls), and 3) 23-hr LDC applied at 22 weeks of age with photoperiods of 14 hr gradually increased to 18 hr. Data were obtained on hen-day egg production (HDP), egg weight, egg mass, egg specific gravity, and yolk weight. The LDC effect was significant (P<.05) for yolk weight with both strains and HDP and egg specific gravity for the UMC strain. The strain effect was nonsignifcant for HDP but highly significant (P-C01) for the other factors studied. The LDLDC depressed early HDP, while SLDC increased HDP for the UMC strain; however, the opposite LDC effect was noted for the C strain. Initial egg weight and egg specific gravity was significantly increased for the UMC strain on the LDLDC; however, LDLDC had no beneficial effect (P>.05) on initial egg specific gravity for the C strain. (Key words: ahemeral lighting, egg production, egg quality, laying hens)
PERFORMANCE AND AHEMERAL' LIGHT-DARK CYCLES
Mangement and Data Collection. Throughout the study, a pelleted layer ration (16.8% protein, 2830 cal/kg ME, 2.96% calcium, .53% available phosphorus) was fed and water was supplied ad libitum. Pullet size oyster shell was sprinkled over the feed every other day to supplement the calcium content of the layer ration. Individual hen records were kept for all ovipositions, and the experimental laying period was extended for 14 periods of 24 days each (336 days). Data obtained for this study were HDP (number eggs per number live hens per day), egg weight, egg mass (number eggs X average egg weight), egg specific gravity for each period, and yolk weight for every even period. Eggs were collected for 3 successive days of lay each period from all 360 hens and stored in a cool room overnight at 13 C and 65% relative humidity for egg quality determinations. Each egg was weighed, and specific gravity was then determined by using the flotation method with NaCL solutions ranging from 1.060 to 1.105 in .005 increments (Roland and Harms, 1974). Eggs from a randomly selected sample of two hens from each strain per group were then broken out on a flat glass surface to record interior quality. The egg yolks were rolled on a wet paper towel to take off any adhering chalaza material, then they were weighed individually. Statistical Analysis. Analysis of variance computed by the Statistical Analysis System (Barr et al, 1979) for a split plot factorial design with strain and LDC as the main effects was used. The least significant difference test (Snedecor and Cochran, 1980) was used to separate means. RESULTS AND DISCUSSION
Percent hen-day egg production of the UMC birds on 24- and 23-hr LDC during the first 4 periods peaked at a higher rate than did that of the C strain (Table 2). Further, HDP was significantly depressed (P<.05) for the UMC strain exposed to the decreasing 26- to 23-hr LDC during the first 5 periods. Rate of lay for the C strain did not differ (P>.05) for the three LDC treatments (Table 2). The overall yearly average HDP showed that both strains had similar egg production for the year. For the C strain, HDP was numerically the best under the 24- and 23-hr LDC, while HDP was numerically the highest for the UMC strain
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23-hr ahemeral LDC, were compared with pullets from a commercial (C) source. Selection procedures for the UMC line were as follows. Hens were used as breeders, based on their production rate in a 23-hr ahemeral LDC during a 10-month laying cycle. The UMC pullets used in this study were offspring of the previous years' parent stock that were selected after 15 generations in this environment. Recent performance characteristics of the UMC strain has been previously presented (Yassin, 1978). Both strains were brooded for 7 weeks in a deep litter floor pen brooder house with windows. They were maintained in pens (3.05 X 3.05 m) with gas brooders for supplemental heat with natural daylight as the light source. A pullet starter ration (20.5% protein, 2698 cal/kg ME, 10.6% calcium, .51% available phosphorus) was fed, and water was given ad libitum. At the end of 7 weeks, the birds were moved to an opentype confinement shelter enclosed with welded wire and maintained in deep litter floor pens (1.86 x 1.86 m) under natural daylight until housed for the experimental laying period. A pullet grower ration (20.5% protein, 2703 cal/kg ME, 1.06% calcium, .51% available phosphorus) was fed, and water was given ad libitum. When the UMC and C strain pullets were 19 and 21 weeks of age, respectively, they were randomly distributed among 12 light-controlled rooms (4.27 X 2.13 m) providing a 24-hr LDC (13L: 11D), each having a maximum of 30 individual cages (40.6 X 25.4 cm). Environmental conditions for each room were the same with the temperature ranging from 18 to 22 C. Five 40-watt incandescent bulbs provided the light source for each room which ranged from 53.8 to 75.3 lx intensity. To allocate the total number of pullets per strain for each room, 8-C strain and 22-UMC strain pullets were housed in each room for a total population of 96-C strain and 264-UMC strain pullets. At 22 weeks of age, three experimental lighting treatments were imposed: 1) a 26-hr LDC decreasing to 23 hr at the end of the laying year, 2) a constant 24-hr LDC (control), and 3) a constant 23-hr LDC. The photoperiod ranged from 14 hr and gradually increased to 18 hr at the end of the study for all experimental treatments. Each LDC treatment consisted of four replicate rooms of 30 birds each for a total of 120 birds. The protocol of the LDC and the amount and duration of photoperiods used in this study is presented in Table 1.
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KOELKEBECK AND BIELLIER TABLE 1. Protocol of light-dark cycles (LDC) and the amount and duration of photoperiods employed
Photoperiods
LDC
24-hr LDC 14L:10D 14.5L:9.5D 14.75L:8.25D 17L:7D 18L:6D
24 24 24 24 24
Total 23-hr LDC 14L:9D 14.5L:8.5D 14.75L:8.25D 17L:6D 18L:5D
23 23 23 23 23
Total 1
2.0 2.5 2.25 0.75 1.5 1.0 2.0 2.0 14.0 7.5 1.5 1.0 2.0 2.0 14.0 7.5 1.5 1.0 2.0 2.0 14.0
Duration of each period was 24 calendar days.
exposed to the 24-hr LDC. These results do not aggree with that of Yassin (1978) who found better HDP for his UMC strain birds exposed to a 23-hr LDC. Foster (1968) compared the egg production of six different strains of hens under LDC of 23, 24, and 25 hr and found that egg production was best for hens exposed to a 25-hr LDC. Rosales et al. (1968) and Morris (1973) have shown that egg production would be depressed if LDC lengths used were in excess of the inherent biological rhythm of a bird. Similar results were noted for this study; HDP was depressed for the UMC strain exposed to the 26- to 23-hr LDC (Table 2). Because the UMC strain hens have been selected for improved reproductive fitness under a short LDC, they may have a short biological rhythm, and thus they can lay at a maximum rate when exposed to a short LDC. Peak HDP occurred for the C strain while being exposed to a 25-hr LDC (Periods 3 and 4), which suggests that this LDC
caused entrainment of oviposition for this strain. The 26- to 23-hr LDC, which was reduced to 25 hr (Periods 3 and 4) produced the best early egg weight for the UMC strain (Table 3); however, this was not the case for the C strain hens. The results of long LDC on egg weight for the UMC strain was consistent with that of Yassin (1978). In that study, C and UMC strain hens were exposed to a decreasing LDC of 27 to 23 hr. Early egg weight was increased for both strains under the long LDC (27 and 26 hr), but egg weight increase was greatest for the UMC strain. In the present study, average yearly egg weight for both strains revealed no significant (P>.05) differences between LDC treatments. Overall egg weight for the C strain was, however, significantly greater (P<.01) than that of the UMC strain. Egg specific gravity presented in Table 4 indicated that the 26- to 23-hr LDC produced greater (P<.05) specific gravity for the C strain
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26 25 24 23 23 23 23 23 Total
26- to 23-hr LDC 14L:12D 14L:11D 14L:10D 14L:9D 14.5L:8.5D 14.75L:8.25D 17L:6D 18L:5D
Duration periods1
PERFORMANCE AND AHEMERAL LIGHT-DARK CYCLES
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TABLE 2. Effect of light-dark cycle (LDC) length on hen-day egg production C 2 Strain LDC (hr) Period
1
UMC2 Strain LDC (hr)
26 to 23
24
23
35.5 83.1 93.1 93.1 91.3 88.8 85.4 84.6 82.3 84.0 83.7 85.3 75.6 69.8 81.1
31.9 80.3 90.6 91.9 92.7 92.1 89.8 88.0 88.8 87.2 85.2 84.4 82.4 79.8 83.2 82.5 3
35.5 83.0 89.8 91.0 91.7 90.8 88.7 88.4 86.8 86.2 88.3 83.2 78.3 82.6 83.2
26 to 23
24
23
39.8 b 75.4 b 85.0 b 84.8 b 82.3 b 86.6 85.9 84.1 83.6 82.5 80.7 80.0 70.4 68.6 77.8 b
64.3 a 87.5 a 93.0 a 93.8 a 90.3 a 91.6 89.9 88.0 87.2 85.0 83.1 78.9 72.5 69.0 83.9 a 81.5
62.9 a 90.2 a 94.1 a 95.2 a 95.0 a 92.6 89.2 87.8 83.6 80.5 77.4 74.6 68.4 68.7 82.9 a
(%)
' Means with different superscripts in each row per strain are significantly different (P<.05). 1 2
Duration of each period was 24 calendar days. C = Commercial, UMC = University of Missouri-Columbia.
'Comparison of overall mean between strains is not significantly different (P>.05).
TABLE 3. Effect of light-dark cycle (LDC) length on egg weight C2 Strain LDC (hr) Period
1
UMC2 Strain LDC (hr)
26 to 23
24
23
26 to 23
24
23
1 2 3 4 5 6 7 8 9 10 11 12 13 14
51.5 56.3 59.1 60.1b 60.3b 61.0 b 62.7 b 64.0 a 64.8 64.7ab 65.9 a 65.7 a 65.2 66.5 a
51.8 56.7 59.7 60.2 b 61.3ab 62.0 a b 62.4 b 62.3 b 64.0 64.3 b 64.4 b 64.1b 64.3 65.2 b
51.4 56.7 59.5 61.3 a 62.3 a 62.9 a 63.8 a 64.5 a 65.0 65.6 a 65.8 a 65.3 a 64.9 66.8 a
49.5 a 52.8 a 55.0 a 55.3 a 54.6 55.2 a b 55.7 56.3 b 56.8ab 57.2 b 57.9ab 58.2 a b 58.1 a 58.9
48.5 b 51.9 b 53.3 b 54.4 b 54.4 54.9 b 55.8 55.6 b 56.7 b 57.2 b 57.2 b 57.4 b 57.0 b 58.5
48.5 b 51.3 b 53.6 b 54.2 b 54.9 55.7 a 56.2 57.2 a 57.6 a 58.2 a 58.7 a 58.5 a 56.9 b 58.3
Mean Mean
62.0
61.6 62.1**
62.6
55.8
55.2 55.6
55.7
(g)
' Means with different superscripts in each row per strain are significantly different (P<.05). 1
Duration of each period was 24 calendar days.
2
C = Commercial, UMC = University of Missouri-Columbia.
•'Comparison of overall mean between strains is significantly different (P<.01).
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mean Mean
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KOELKEBECK AND BIELLIER TABLE 4. Effect of light-dark cycle (LDC) length on egg specific gravity C 2 Strain LDC (hr)
Period
1
UMC 2 Strain LDC (hr)
24
23
26 t o 23
24
23
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1.099a 1.093 1.090a 1.089 1.087 1.089 1.087ab 1.085b 1.084 1.084 1.083 1.083 1.084ab 1.082
1.095b 1.093 1.089ab 1.089 1.088 1.088 1.086b 1.085b 1.085 1.084 1.085 1.084 1.086a 1.084
1.095b 1.093 1.088b 1.089 1.089 1.089 1.088a 1.087a 1.085 1.085 1.084 1.084 1.084b 1.083
1.095a 1.090a 1.086a 1.087a 1.084a 1.084a 1.082 1.079 1.079 1.079a 1.078a 1.078a 1.078a 1.078a
1.090b 1.087b 1.084b 1.085b 1.083b 1.082b 1.081 1.079 1.078 1.077b 1.077b 1.076b 1.077 a 1.077ab
1.089b 1.086c 1.082c 1.083c 1.082b 1.083b 1.081 1.079 1.079 1.079 a 1.077b 1.076b 1.075b 1.076
Mean Mean
1.087
1.087 1.087*'
1.087
1.083a
1.081b 1.081
1.080b
ab ' Means with different superscripts in each row per strain are significantly different (P<.05). 1 2
Duration of each period was 24 calendar days. C = Commerical, UMC = University of Missouri-Columbia.
*'Comparison of overall mean between strains is significantly different (P<.01).
during t h e first period. T h e 26- to 23-hr LDC for t h e UMC strain rendered higher ( P < . 0 5 ) specific gravity t h a n t h e 24- or 23-hr L D C during t h e first 6 periods. Egg specific gravity for t h e UMC strain u n d e r t h e L D L D C was n o t surpassed b y t h e o t h e r LDC t r e a t m e n t s at any period and maintained higher quality during t h e last 4 periods. These results agree with Yassin ( 1 9 7 8 ) w h o f o u n d t h a t a 2 7 - t o 23-hr decreasing LDC produced b e t t e r egg specific gravity for b o t h C and UMC strains during t h e first 3 laying periods. T h e 26- t o 23-hr LDC affected overall egg specific gravity for t h e UMC strain only (Table 4 ) . This occurred because of t h e early significant increase in egg specific gravity for this strain (Periods 1 t o 6, Table 4 ) . Even though t h e LDC t r e a t m e n t s did n o t significantly affect ( P > . 0 5 ) egg specific gravity for t h e C strain, overall egg specific gravity was significantly greater ( P < . 0 1 ) t h a n t h e UMC strain. In this s t u d y , t h e t r e n d s for egg mass followed t h a t for H D P and egg weight. T h e results presented in Table 5 show t h a t a significant strain difference was found, with t h e C strain exhibiting higher ( P < . 0 1 ) overall egg mass. This
TABLE 5. Effect of strain and light-dark cycle (LDC) length on egg mass and yolk weight
LDC
Yolk weight 2
Egg mass 1
(hr)
Kg) C Strain
26 t o 23 24 23 Mean
1237.2 1238.5 1247.7 1240.3**
16.9b 18.2a 17.lb 17.4**
UMC Strain 2 6 t o 23 24 23 Mean
1084.0 1129.7 1114.4 1109.4
15.8b 15.5b 16.2a 15.8
' Means with different superscripts in the same column per strain are significantly different (P<.05). •Means are average per period for 14 periods (24 days) of lay. 2 Means are average per period for weights taken every even period (Periods 2, 4, 6, 8, 10, 12, and 14).
*'Comparison of overall mean between strains is significantly different (P<.01).
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26 t o 23
PERFORMANCE AND AHEMERAL LIGHT-DARK CYCLES
In this study, two strains of SCWL hens were tested throughout a laying cycle for reproductive fitness under several ahemeral lighting programs. The UMC strain, selected for improved reproductive capabilities under a SLDC, responded the most to the lighting schedules employed; i.e., significant differences between LDC programs were found for HDP, egg specific gravity, and yolk weight. Initial pullet egg weight and specific gravity for the UMC strain was increased by the use of the LDLDC in the beginning of the laying year. Shortening this LDC during the latter part of the laying year failed, however, to improve egg production for either strain as compared to the control LDC (24 hr). The use of a SLDC throughout the laying year did, however, improve HDP for the UMC strain during the first part of the laying cycle. Further testing of various ahemeral LDC programs for commercial strain hens will be needed to demonstrate beneficial effects on production and egg quality characteristics.
ACKNOWLEDGMENTS
The authors wish to thank J. Sebaugh for
her assistance in data analysis. The technical assistance of S. Liou, O. Yassin, and V. Christensen was also greatly appreciated. REFERENCES Barr, A. J., J. H. Goodnight, J. P. Sell, W. H. Blair, and D. M. Chilko, 1979. SAS User's Guide. 9th ed. J. T. Helwig and K. A. Council, ed. SAS Inst., Raleigh, NC. Biellier, H. V., K. W. Koelkebeck, and O. E. Yassin, 1978. Use of ahemeral light-dark cycles to select hens with short intervals between oviposition. Poultry Sci. 57:1119. (Abstr.) Cahaner, A., and H. Abplanalp, 1979. Changes in egg production and egg intervals under selection for high egg number under 22 hour day cycles of artificial lighting. Poultry Sci. 58:757-761. Cooper, J. B., and B. D. Barnett, 1976. Ahemeral photoperiods for chicken hens. Poultry Sci. 55:1183-1187. Davis, G. T., T. W. Wilcox, and A. F. Beechler, 1964. Photoperiodic response of chickens. Poultry Sci. 43:805-811. Foster, W. H., 1968. The effect of light-dark cycles of abnormal lengths upon egg production. Br. Poult. Sci. 9:273-284. Foster, W. H., 1969. Egg production under 24-, 26-, and 28-hour light-dark cycles. Br. Pout. Sci. 10:273279. Leeson, S., J. D. Summers, and R. J. Etches, 1979. Effect of a 28-hour light:dark cycle on egg shell quality and end-of-lay birds. Poultry Sci. 58:285287. Marks, H. L., and L. M. Lucas, 1963. Time of oviposition under "short days." Poultry Sci. 42:14661468. Melek, O. R., T. R. Morris, and R. C. Jennings, 1973. The time factor in egg formation for hens exposed to ahemeral light-dark cycles. Br. Poult. Sci. 14:493-498. Morris, T. R., 1973. The effects of ahemeral light and dark cycles on egg production in the fowl. Poultry Sci. 52:423-445. Morris, T. R., and S. Fox, 1971. Ahemeral light-dark cycles and egg weight in the fowl. Poult. Testing 1:71-73. Cited by Foster, W. H., 1972. Pages 161-183 in Egg Formation and Production. B. M. Freeman and P. E. Lake, ed., Br. Poult. Sci. Ltd., Edinburgh, Scotland. Nordstrom, J. O., 1982. Shell quality of eggs from hens exposed to 26- and 27-hour light-dark cycles from 56 to 76 weeks of age. Poultry Sci. 61:804812. Nordstrom, J. O., and L. E. Ousterhout, 1983. Ahemeral light cycles and protein levels for older laying hens. Poultry Sci. 62:525-531. Roland, D. A., Sr., and R. H. Harms, 1974. Specific gravity of eggs in relation to egg weight and time of oviposition. Poultry Sci. 53:1494-1498. Rosales, A. A., H. V. Biellier, and A. B. Stephenson, 1968. Effects of light cycles on oviposition and egg production. Poultry Sci. 47:586-591. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 7th ed. Iowa State Univ. Press, Ames, IA. Woodard, A. E., W. O. Wilson, and H. Abplanalp,
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was due to the greater egg weight found for the C strain. Similar strain differences were also found by Yassin (1978). In the present study, the greatest egg mass was that obtained by the C strain hens under the 23-hr LDC, while for the UMC strain, the greatest egg mass was that of the hens exposed to the 24-hr LDC. These results do not suggest, however, that the UMC strain is not as fit in a 23-hr LDC vs. a 24-hr LDC environment, because these differences were only numerical. Overall egg yolk weight means for both strains (Table 5) indicated different strain responses to the LDC treatments. Among the C strain birds, 24-hr HDC rendered significantly greater (P<.05) yolk, whereas yolk weight for the UMC strain was significantly greater (P<.05) for the 23-hr LDC. This result occurred possibly because the LDC was not long enough, and different results between this study and that of Morris (1973) may have been due to LDC differences. Data presented in the present study does, however, agree with that of Yassin (1978), i.e., better yolk weight from hens exposed to a short LDC of 23 hr vs. a 24-hr LDC or a decreasing LDC. Results from both studies suggest that the SLDC (23 hr) seems to provide the better environment for maximum egg yolk formation.
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880 1962. Rhythm of lay in by a 16 hour "day." 1762. Yannakopoulos, A. L., and T. of light, vitamin D and
KOELKEBECK AND BIELLIER chickens as influenced Poultry Sci. 41:1758R. Morris, 1979. Effect dietary phosphorus on
egg-shell quality late in the pullet laying year. Br. Poult. Sci. 20:337-342. Yassin, O. E., 1978. The photoperiodic and ahemeral light-dark cycle effect on White Leghorn layers. Ph.D. thesis, Univ. of Missouri, Columbia, MO.
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1986 Poultry Science 65:874-880 INTRODUCTION A n y c o m b i n a t i o n of light and dark phases t h a t do n o t add up t o 2 4 hr have been t e r m e d " a h e m e r a l " by Morris and F o x ( 1 9 7 1 ) . Research using a light-dark cycle (LDC) shorter t h a n 24 hr has p r o d u c e d conflicting results. Woodard et al. (1962), Marks and Lucas ( 1 9 6 3 ) , and Davis et al. ( 1 9 6 4 ) e m p l o y e d LDC of 16, 18, or 2 0 hr. They f o u n d t h a t egg p r o d u c t i o n was lower for these LDC t h a n a 24-hr LDC. More recently, Yassin ( 1 9 7 8 ) r e p o r t e d t h a t a 23-hr LDC resulted in better hen-day egg p r o d u c t i o n (HDP) t h a n a 24-hr LDC w h e n applied t o an inbred flock of hens. Ahemeral LDC shorter t h a n 2 4 hr have been used mainly in selection programs, where birds which have an inherent ability t o lay at intervals less t h a n 2 4 h r can b e identified (Biellier et al, 1 9 7 8 ; Cahaner and Abplanalp, 1979).
1 Based on a portion of a thesis submitted by the senior author in partial fulfillment of the requirements for the degree of Masters of Science at the University of Missouri. a Contribution from the Missouri Agricultural Experiment Station, Journal Series Number 9977. 3 Present address: Department of Poultry Science, Texas A&M University, College Station, TX 77843.
T h e use of ahemeral LDC t h a t are longer t h a n 2 4 hr has received more a t t e n t i o n b y w o r k e r s a t t e m p t i n g to achieve b e t t e r egg quality from existing flocks (Foster, 1 9 6 9 ; Morris, 1 9 7 3 ; Leeson et al, 1 9 7 9 ; Yannak o p o u l o s and Morris, 1 9 7 9 ; N o r d s t r o m , 1 9 8 2 ; N o r d s t r o m and O u s t e r h o u t , 1983) Morris ( 1 9 7 3 ) , M e l e k et al. ( 1 9 7 3 ) , Cooper and Barnett ( 1 9 7 6 ) , and Yassin ( 1 9 7 8 ) have all s h o w n t h a t increased egg weight and shell quality can be o b t a i n e d a t t h e expense of egg n u m b e r s by using long LDC t h r o u g h o u t a laying cycle. N o r d s t r o m ( 1 9 8 2 ) and N o r d s t r o m and Ousterh o u t ( 1 9 8 3 ) d e m o n s t r a t e d t h a t exposing laying hens t o long ahemeral LDC at t h e end of their laying year w o u l d dramatically improve egg shell quality. T h e purpose of this s t u d y was t o use a long b u t decreasing light-dark cycle (LDLDC) t o increase initial pullet egg weight and shell quality, t h e n shorten this LDC t o a u g m e n t HDP. F o r comparison, a 24-hr LDC (control) and a short light-dark cycle (SLDC) t r e a t m e n t was used t h r o u g h o u t t h e laying year.
MATERIALS AND METHODS
Experimental Design. Pullets from an inbred strain of Single C o m b White Leghorn (SCWL) chickens, selected at t h e University of MissouriColumbia (UMC) for reproductive fitness in a
874
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ABSTRACT To compare the effects of a long but decreasing light-dark cycle (LDLDC) on egg weight and shell quality and a short light-dark cycle (SLDC) on egg production, 264 University of Missouri-Columbia (UMC) Single Comb White Leghorn (SCWL) pullets and 96 SCWL pullets from a leading commercial (C) strain were individually caged in light-controlled rooms. Treatments were: 1) 26-hr light-dark cycle (LDC) reduced to 23 hr, 2) 24-hr LDC (controls), and 3) 23-hr LDC applied at 22 weeks of age with photoperiods of 14 hr gradually increased to 18 hr. Data were obtained on hen-day egg production (HDP), egg weight, egg mass, egg specific gravity, and yolk weight. The LDC effect was significant (P<.05) for yolk weight with both strains and HDP and egg specific gravity for the UMC strain. The strain effect was nonsignifcant for HDP but highly significant (P-C01) for the other factors studied. The LDLDC depressed early HDP, while SLDC increased HDP for the UMC strain; however, the opposite LDC effect was noted for the C strain. Initial egg weight and egg specific gravity was significantly increased for the UMC strain on the LDLDC; however, LDLDC had no beneficial effect (P>.05) on initial egg specific gravity for the C strain. (Key words: ahemeral lighting, egg production, egg quality, laying hens)
PERFORMANCE AND AHEMERAL' LIGHT-DARK CYCLES
Mangement and Data Collection. Throughout the study, a pelleted layer ration (16.8% protein, 2830 cal/kg ME, 2.96% calcium, .53% available phosphorus) was fed and water was supplied ad libitum. Pullet size oyster shell was sprinkled over the feed every other day to supplement the calcium content of the layer ration. Individual hen records were kept for all ovipositions, and the experimental laying period was extended for 14 periods of 24 days each (336 days). Data obtained for this study were HDP (number eggs per number live hens per day), egg weight, egg mass (number eggs X average egg weight), egg specific gravity for each period, and yolk weight for every even period. Eggs were collected for 3 successive days of lay each period from all 360 hens and stored in a cool room overnight at 13 C and 65% relative humidity for egg quality determinations. Each egg was weighed, and specific gravity was then determined by using the flotation method with NaCL solutions ranging from 1.060 to 1.105 in .005 increments (Roland and Harms, 1974). Eggs from a randomly selected sample of two hens from each strain per group were then broken out on a flat glass surface to record interior quality. The egg yolks were rolled on a wet paper towel to take off any adhering chalaza material, then they were weighed individually. Statistical Analysis. Analysis of variance computed by the Statistical Analysis System (Barr et al, 1979) for a split plot factorial design with strain and LDC as the main effects was used. The least significant difference test (Snedecor and Cochran, 1980) was used to separate means. RESULTS AND DISCUSSION
Percent hen-day egg production of the UMC birds on 24- and 23-hr LDC during the first 4 periods peaked at a higher rate than did that of the C strain (Table 2). Further, HDP was significantly depressed (P<.05) for the UMC strain exposed to the decreasing 26- to 23-hr LDC during the first 5 periods. Rate of lay for the C strain did not differ (P>.05) for the three LDC treatments (Table 2). The overall yearly average HDP showed that both strains had similar egg production for the year. For the C strain, HDP was numerically the best under the 24- and 23-hr LDC, while HDP was numerically the highest for the UMC strain
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23-hr ahemeral LDC, were compared with pullets from a commercial (C) source. Selection procedures for the UMC line were as follows. Hens were used as breeders, based on their production rate in a 23-hr ahemeral LDC during a 10-month laying cycle. The UMC pullets used in this study were offspring of the previous years' parent stock that were selected after 15 generations in this environment. Recent performance characteristics of the UMC strain has been previously presented (Yassin, 1978). Both strains were brooded for 7 weeks in a deep litter floor pen brooder house with windows. They were maintained in pens (3.05 X 3.05 m) with gas brooders for supplemental heat with natural daylight as the light source. A pullet starter ration (20.5% protein, 2698 cal/kg ME, 10.6% calcium, .51% available phosphorus) was fed, and water was given ad libitum. At the end of 7 weeks, the birds were moved to an opentype confinement shelter enclosed with welded wire and maintained in deep litter floor pens (1.86 x 1.86 m) under natural daylight until housed for the experimental laying period. A pullet grower ration (20.5% protein, 2703 cal/kg ME, 1.06% calcium, .51% available phosphorus) was fed, and water was given ad libitum. When the UMC and C strain pullets were 19 and 21 weeks of age, respectively, they were randomly distributed among 12 light-controlled rooms (4.27 X 2.13 m) providing a 24-hr LDC (13L: 11D), each having a maximum of 30 individual cages (40.6 X 25.4 cm). Environmental conditions for each room were the same with the temperature ranging from 18 to 22 C. Five 40-watt incandescent bulbs provided the light source for each room which ranged from 53.8 to 75.3 lx intensity. To allocate the total number of pullets per strain for each room, 8-C strain and 22-UMC strain pullets were housed in each room for a total population of 96-C strain and 264-UMC strain pullets. At 22 weeks of age, three experimental lighting treatments were imposed: 1) a 26-hr LDC decreasing to 23 hr at the end of the laying year, 2) a constant 24-hr LDC (control), and 3) a constant 23-hr LDC. The photoperiod ranged from 14 hr and gradually increased to 18 hr at the end of the study for all experimental treatments. Each LDC treatment consisted of four replicate rooms of 30 birds each for a total of 120 birds. The protocol of the LDC and the amount and duration of photoperiods used in this study is presented in Table 1.
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KOELKEBECK AND BIELLIER TABLE 1. Protocol of light-dark cycles (LDC) and the amount and duration of photoperiods employed
Photoperiods
LDC
24-hr LDC 14L:10D 14.5L:9.5D 14.75L:8.25D 17L:7D 18L:6D
24 24 24 24 24
Total 23-hr LDC 14L:9D 14.5L:8.5D 14.75L:8.25D 17L:6D 18L:5D
23 23 23 23 23
Total 1
2.0 2.5 2.25 0.75 1.5 1.0 2.0 2.0 14.0 7.5 1.5 1.0 2.0 2.0 14.0 7.5 1.5 1.0 2.0 2.0 14.0
Duration of each period was 24 calendar days.
exposed to the 24-hr LDC. These results do not aggree with that of Yassin (1978) who found better HDP for his UMC strain birds exposed to a 23-hr LDC. Foster (1968) compared the egg production of six different strains of hens under LDC of 23, 24, and 25 hr and found that egg production was best for hens exposed to a 25-hr LDC. Rosales et al. (1968) and Morris (1973) have shown that egg production would be depressed if LDC lengths used were in excess of the inherent biological rhythm of a bird. Similar results were noted for this study; HDP was depressed for the UMC strain exposed to the 26- to 23-hr LDC (Table 2). Because the UMC strain hens have been selected for improved reproductive fitness under a short LDC, they may have a short biological rhythm, and thus they can lay at a maximum rate when exposed to a short LDC. Peak HDP occurred for the C strain while being exposed to a 25-hr LDC (Periods 3 and 4), which suggests that this LDC
caused entrainment of oviposition for this strain. The 26- to 23-hr LDC, which was reduced to 25 hr (Periods 3 and 4) produced the best early egg weight for the UMC strain (Table 3); however, this was not the case for the C strain hens. The results of long LDC on egg weight for the UMC strain was consistent with that of Yassin (1978). In that study, C and UMC strain hens were exposed to a decreasing LDC of 27 to 23 hr. Early egg weight was increased for both strains under the long LDC (27 and 26 hr), but egg weight increase was greatest for the UMC strain. In the present study, average yearly egg weight for both strains revealed no significant (P>.05) differences between LDC treatments. Overall egg weight for the C strain was, however, significantly greater (P<.01) than that of the UMC strain. Egg specific gravity presented in Table 4 indicated that the 26- to 23-hr LDC produced greater (P<.05) specific gravity for the C strain
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26 25 24 23 23 23 23 23 Total
26- to 23-hr LDC 14L:12D 14L:11D 14L:10D 14L:9D 14.5L:8.5D 14.75L:8.25D 17L:6D 18L:5D
Duration periods1
PERFORMANCE AND AHEMERAL LIGHT-DARK CYCLES
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TABLE 2. Effect of light-dark cycle (LDC) length on hen-day egg production C 2 Strain LDC (hr) Period
1
UMC2 Strain LDC (hr)
26 to 23
24
23
35.5 83.1 93.1 93.1 91.3 88.8 85.4 84.6 82.3 84.0 83.7 85.3 75.6 69.8 81.1
31.9 80.3 90.6 91.9 92.7 92.1 89.8 88.0 88.8 87.2 85.2 84.4 82.4 79.8 83.2 82.5 3
35.5 83.0 89.8 91.0 91.7 90.8 88.7 88.4 86.8 86.2 88.3 83.2 78.3 82.6 83.2
26 to 23
24
23
39.8 b 75.4 b 85.0 b 84.8 b 82.3 b 86.6 85.9 84.1 83.6 82.5 80.7 80.0 70.4 68.6 77.8 b
64.3 a 87.5 a 93.0 a 93.8 a 90.3 a 91.6 89.9 88.0 87.2 85.0 83.1 78.9 72.5 69.0 83.9 a 81.5
62.9 a 90.2 a 94.1 a 95.2 a 95.0 a 92.6 89.2 87.8 83.6 80.5 77.4 74.6 68.4 68.7 82.9 a
(%)
' Means with different superscripts in each row per strain are significantly different (P<.05). 1 2
Duration of each period was 24 calendar days. C = Commercial, UMC = University of Missouri-Columbia.
'Comparison of overall mean between strains is not significantly different (P>.05).
TABLE 3. Effect of light-dark cycle (LDC) length on egg weight C2 Strain LDC (hr) Period
1
UMC2 Strain LDC (hr)
26 to 23
24
23
26 to 23
24
23
1 2 3 4 5 6 7 8 9 10 11 12 13 14
51.5 56.3 59.1 60.1b 60.3b 61.0 b 62.7 b 64.0 a 64.8 64.7ab 65.9 a 65.7 a 65.2 66.5 a
51.8 56.7 59.7 60.2 b 61.3ab 62.0 a b 62.4 b 62.3 b 64.0 64.3 b 64.4 b 64.1b 64.3 65.2 b
51.4 56.7 59.5 61.3 a 62.3 a 62.9 a 63.8 a 64.5 a 65.0 65.6 a 65.8 a 65.3 a 64.9 66.8 a
49.5 a 52.8 a 55.0 a 55.3 a 54.6 55.2 a b 55.7 56.3 b 56.8ab 57.2 b 57.9ab 58.2 a b 58.1 a 58.9
48.5 b 51.9 b 53.3 b 54.4 b 54.4 54.9 b 55.8 55.6 b 56.7 b 57.2 b 57.2 b 57.4 b 57.0 b 58.5
48.5 b 51.3 b 53.6 b 54.2 b 54.9 55.7 a 56.2 57.2 a 57.6 a 58.2 a 58.7 a 58.5 a 56.9 b 58.3
Mean Mean
62.0
61.6 62.1**
62.6
55.8
55.2 55.6
55.7
(g)
' Means with different superscripts in each row per strain are significantly different (P<.05). 1
Duration of each period was 24 calendar days.
2
C = Commercial, UMC = University of Missouri-Columbia.
•'Comparison of overall mean between strains is significantly different (P<.01).
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mean Mean
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KOELKEBECK AND BIELLIER TABLE 4. Effect of light-dark cycle (LDC) length on egg specific gravity C 2 Strain LDC (hr)
Period
1
UMC 2 Strain LDC (hr)
24
23
26 t o 23
24
23
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1.099a 1.093 1.090a 1.089 1.087 1.089 1.087ab 1.085b 1.084 1.084 1.083 1.083 1.084ab 1.082
1.095b 1.093 1.089ab 1.089 1.088 1.088 1.086b 1.085b 1.085 1.084 1.085 1.084 1.086a 1.084
1.095b 1.093 1.088b 1.089 1.089 1.089 1.088a 1.087a 1.085 1.085 1.084 1.084 1.084b 1.083
1.095a 1.090a 1.086a 1.087a 1.084a 1.084a 1.082 1.079 1.079 1.079a 1.078a 1.078a 1.078a 1.078a
1.090b 1.087b 1.084b 1.085b 1.083b 1.082b 1.081 1.079 1.078 1.077b 1.077b 1.076b 1.077 a 1.077ab
1.089b 1.086c 1.082c 1.083c 1.082b 1.083b 1.081 1.079 1.079 1.079 a 1.077b 1.076b 1.075b 1.076
Mean Mean
1.087
1.087 1.087*'
1.087
1.083a
1.081b 1.081
1.080b
ab ' Means with different superscripts in each row per strain are significantly different (P<.05). 1 2
Duration of each period was 24 calendar days. C = Commerical, UMC = University of Missouri-Columbia.
*'Comparison of overall mean between strains is significantly different (P<.01).
during t h e first period. T h e 26- to 23-hr LDC for t h e UMC strain rendered higher ( P < . 0 5 ) specific gravity t h a n t h e 24- or 23-hr L D C during t h e first 6 periods. Egg specific gravity for t h e UMC strain u n d e r t h e L D L D C was n o t surpassed b y t h e o t h e r LDC t r e a t m e n t s at any period and maintained higher quality during t h e last 4 periods. These results agree with Yassin ( 1 9 7 8 ) w h o f o u n d t h a t a 2 7 - t o 23-hr decreasing LDC produced b e t t e r egg specific gravity for b o t h C and UMC strains during t h e first 3 laying periods. T h e 26- t o 23-hr LDC affected overall egg specific gravity for t h e UMC strain only (Table 4 ) . This occurred because of t h e early significant increase in egg specific gravity for this strain (Periods 1 t o 6, Table 4 ) . Even though t h e LDC t r e a t m e n t s did n o t significantly affect ( P > . 0 5 ) egg specific gravity for t h e C strain, overall egg specific gravity was significantly greater ( P < . 0 1 ) t h a n t h e UMC strain. In this s t u d y , t h e t r e n d s for egg mass followed t h a t for H D P and egg weight. T h e results presented in Table 5 show t h a t a significant strain difference was found, with t h e C strain exhibiting higher ( P < . 0 1 ) overall egg mass. This
TABLE 5. Effect of strain and light-dark cycle (LDC) length on egg mass and yolk weight
LDC
Yolk weight 2
Egg mass 1
(hr)
Kg) C Strain
26 t o 23 24 23 Mean
1237.2 1238.5 1247.7 1240.3**
16.9b 18.2a 17.lb 17.4**
UMC Strain 2 6 t o 23 24 23 Mean
1084.0 1129.7 1114.4 1109.4
15.8b 15.5b 16.2a 15.8
' Means with different superscripts in the same column per strain are significantly different (P<.05). •Means are average per period for 14 periods (24 days) of lay. 2 Means are average per period for weights taken every even period (Periods 2, 4, 6, 8, 10, 12, and 14).
*'Comparison of overall mean between strains is significantly different (P<.01).
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26 t o 23
PERFORMANCE AND AHEMERAL LIGHT-DARK CYCLES
In this study, two strains of SCWL hens were tested throughout a laying cycle for reproductive fitness under several ahemeral lighting programs. The UMC strain, selected for improved reproductive capabilities under a SLDC, responded the most to the lighting schedules employed; i.e., significant differences between LDC programs were found for HDP, egg specific gravity, and yolk weight. Initial pullet egg weight and specific gravity for the UMC strain was increased by the use of the LDLDC in the beginning of the laying year. Shortening this LDC during the latter part of the laying year failed, however, to improve egg production for either strain as compared to the control LDC (24 hr). The use of a SLDC throughout the laying year did, however, improve HDP for the UMC strain during the first part of the laying cycle. Further testing of various ahemeral LDC programs for commercial strain hens will be needed to demonstrate beneficial effects on production and egg quality characteristics.
ACKNOWLEDGMENTS
The authors wish to thank J. Sebaugh for
her assistance in data analysis. The technical assistance of S. Liou, O. Yassin, and V. Christensen was also greatly appreciated. REFERENCES Barr, A. J., J. H. Goodnight, J. P. Sell, W. H. Blair, and D. M. Chilko, 1979. SAS User's Guide. 9th ed. J. T. Helwig and K. A. Council, ed. SAS Inst., Raleigh, NC. Biellier, H. V., K. W. Koelkebeck, and O. E. Yassin, 1978. Use of ahemeral light-dark cycles to select hens with short intervals between oviposition. Poultry Sci. 57:1119. (Abstr.) Cahaner, A., and H. Abplanalp, 1979. Changes in egg production and egg intervals under selection for high egg number under 22 hour day cycles of artificial lighting. Poultry Sci. 58:757-761. Cooper, J. B., and B. D. Barnett, 1976. Ahemeral photoperiods for chicken hens. Poultry Sci. 55:1183-1187. Davis, G. T., T. W. Wilcox, and A. F. Beechler, 1964. Photoperiodic response of chickens. Poultry Sci. 43:805-811. Foster, W. H., 1968. The effect of light-dark cycles of abnormal lengths upon egg production. Br. Poult. Sci. 9:273-284. Foster, W. H., 1969. Egg production under 24-, 26-, and 28-hour light-dark cycles. Br. Pout. Sci. 10:273279. Leeson, S., J. D. Summers, and R. J. Etches, 1979. Effect of a 28-hour light:dark cycle on egg shell quality and end-of-lay birds. Poultry Sci. 58:285287. Marks, H. L., and L. M. Lucas, 1963. Time of oviposition under "short days." Poultry Sci. 42:14661468. Melek, O. R., T. R. Morris, and R. C. Jennings, 1973. The time factor in egg formation for hens exposed to ahemeral light-dark cycles. Br. Poult. Sci. 14:493-498. Morris, T. R., 1973. The effects of ahemeral light and dark cycles on egg production in the fowl. Poultry Sci. 52:423-445. Morris, T. R., and S. Fox, 1971. Ahemeral light-dark cycles and egg weight in the fowl. Poult. Testing 1:71-73. Cited by Foster, W. H., 1972. Pages 161-183 in Egg Formation and Production. B. M. Freeman and P. E. Lake, ed., Br. Poult. Sci. Ltd., Edinburgh, Scotland. Nordstrom, J. O., 1982. Shell quality of eggs from hens exposed to 26- and 27-hour light-dark cycles from 56 to 76 weeks of age. Poultry Sci. 61:804812. Nordstrom, J. O., and L. E. Ousterhout, 1983. Ahemeral light cycles and protein levels for older laying hens. Poultry Sci. 62:525-531. Roland, D. A., Sr., and R. H. Harms, 1974. Specific gravity of eggs in relation to egg weight and time of oviposition. Poultry Sci. 53:1494-1498. Rosales, A. A., H. V. Biellier, and A. B. Stephenson, 1968. Effects of light cycles on oviposition and egg production. Poultry Sci. 47:586-591. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 7th ed. Iowa State Univ. Press, Ames, IA. Woodard, A. E., W. O. Wilson, and H. Abplanalp,
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was due to the greater egg weight found for the C strain. Similar strain differences were also found by Yassin (1978). In the present study, the greatest egg mass was that obtained by the C strain hens under the 23-hr LDC, while for the UMC strain, the greatest egg mass was that of the hens exposed to the 24-hr LDC. These results do not suggest, however, that the UMC strain is not as fit in a 23-hr LDC vs. a 24-hr LDC environment, because these differences were only numerical. Overall egg yolk weight means for both strains (Table 5) indicated different strain responses to the LDC treatments. Among the C strain birds, 24-hr HDC rendered significantly greater (P<.05) yolk, whereas yolk weight for the UMC strain was significantly greater (P<.05) for the 23-hr LDC. This result occurred possibly because the LDC was not long enough, and different results between this study and that of Morris (1973) may have been due to LDC differences. Data presented in the present study does, however, agree with that of Yassin (1978), i.e., better yolk weight from hens exposed to a short LDC of 23 hr vs. a 24-hr LDC or a decreasing LDC. Results from both studies suggest that the SLDC (23 hr) seems to provide the better environment for maximum egg yolk formation.
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880 1962. Rhythm of lay in by a 16 hour "day." 1762. Yannakopoulos, A. L., and T. of light, vitamin D and
KOELKEBECK AND BIELLIER chickens as influenced Poultry Sci. 41:1758R. Morris, 1979. Effect dietary phosphorus on
egg-shell quality late in the pullet laying year. Br. Poult. Sci. 20:337-342. Yassin, O. E., 1978. The photoperiodic and ahemeral light-dark cycle effect on White Leghorn layers. Ph.D. thesis, Univ. of Missouri, Columbia, MO.
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