The Use of Artificial Lights for Turkeys* H. L. WlLCKE Iowa Agricultural Experiment Station, Ames, Iowa (Presented at Annual Meeting, August 1938; received for publication September 22, 1938) THE production of turkey hatching eggs on a commercial scale has brought out the problems of increasing the egg production of the breeding females, and of producing earlier eggs to supply the demand for early poults. From the results of previous experimental work it would seem that the use of artificial lights might be the most promising method of obtaining these results. While work has been reported indicating that turkeys can be brought into production earlier by the use of artificial lights, the length of the lighting period prior to production has not been determined definitely and the effect of lights upon early fertility seemed debatable, although Albright and Thompson (1933, 1934) had obtained some evidence that the use of artificial lights injured neither the birds nor the hatchability. These workers also reported that egg production could be increased by the use of artificial lights, having obtained an average annual record of 124.8 eggs for 14 bronze pullets. It was found in this work that the first egg was produced on December 26 when morning lights were begun on December 1. Since this work was done in Oklahoma, there was some question as to whether the same relative time would be required for the onset of production in more northern latitudes. Moore and Berridge (1934) found that when morning lights were turned on at 5:00 a.m. on January 1, 1932, 1933, and 1934, the first eggs were produced January Journal Paper No. J-576 of the Iowa Agricultural Experiment Station. Project 64. [236] 24 to 27 as contrasted to the production of the first eggs from the turkey breeders on 24 in 1930 and 1931. While these birds were not compared during the same year, there is definite indication that artificial lights stimulated earlier production. Similar results have been reported by the Nebraska Station (1930) by Marsden (1936) and by Scott and Payne (1937) who not only were able to show that the birds were brought into production at an earlier date by the use of artificial lights, but also that the longer wave lengths obtained by the use of either unfiltered or red light stimulated the turkeys to earlier production, whereas the shorter wave lengths transmitted through the blue filter were not effective. Charles, Wilcox, Flagg, and Tepper (1937) found that egg production could be stimulated by confinement and artificial lights with no significant differences in egg size, maintenance of body weight or hatchability. In this work, the birds subjected to morning lights came into production eight weeks before those which were on open range. The average total production for the 24 week period of the experiment was 36.08 eggs for the lighted birds and 30.45 for the open range lot. Lee, Hamilton, Henry, and Callanan (1937) have found that the use of supplementary heat reduced the total feed consumption of New Hampshires and S. C. White Leghorns and their data indicate a decrease in egg production in the heated pens. No reports of the effect of such heat on turkeys have come to our attention.
THE USE OF ARTIFICIAL LIGHTS FOR TURKEYS 237 The investigations reported in this paper were undertaken to obtain additional evidence upon the length of lighting period required to stimulate production in turkey females, and to study the effect of this stimulation upon the fertility and hatchability of the eggs and upon the feed consumption of the birds. Preliminary results records were obtained during each month of the experimental period insofar as this was practical. Lights were discontinued on 1 of each year and all experiments were terminated in. The percentage production for each group of birds for each year was calculated for bi-weekly periods on a pullet-day basis. IS 31 15 30 15 MAE. APR. MAY on the effect of heat on these factors are included. EXPERIMENTAL During each of the first years of this experiment, full sister turkey females were used to make up the various pens, allowing equal floor space per bird in each pen. The birds were fed a standard laying ration which was in use for chickens. All pens were trap-nested and egg weights were recorded except in 193S. Fertility and hatchability 15 ZS FEb. FIG. 1. Percentage production of turkey females at bi-weekly intervals. 15 SO 15 31 15 SO APR. MAY JUNE EGG PRODUCTION In 193S, two pens of pullets were housed, and a SO watt bulb was turned on at 5:30 a.m. daily beginning IS, and again at dusk until 8:00 p.m. As shown in Figure 1, the first egg was laid by the lighted group on 5, while in the unlighted flock the first egg was laid on 23. When lights were turned on at this comparatively late date, egg production resulted after the use of lights for two weeks, whereas the unlighted birds came
238 H. L. WlLCKE into production 18 days later. The two groups were quite equally uniform in production during the laying season except for the two bi-weekly periods ending 15 and 15, and in both cases the production was sustained more uniformly in the lighted group. Both and White Hollands were used in 1936, and all-night lights were turned on January 1, using a 25 watt bulb with a metal reflector. The first egg was laid by the lighted White Holland flock on Date e 1935 (Mar -) 1936 (Feb.-) 1937 (Feb.-) 1938 (Jan.--Tune) Heat 84.1 TABLE Lighted 50.00 45.00 60.00 January 27, as shown in Figure 1 but the did not respond to the light stimulus until 16, 47 days after the use of lights was initiated, and 20 days after the first egg was obtained from the White Hollands. Both the unlighted pens came into production at practically the same time, on 15 and 16. Although the came into production later, the percentage production in that pen was much higher later in the season. As in 1935, the lighted birds produced a greater number of eggs in the period ending 30 than did the unlighted birds. In 1937, all night lights were turned on 4, and the first egg was laid 24 days later (Feb. 28) in the lighted pen, only 11 days earlier than production started in the unlighted pen. However, it will be noted in Figure 1 that the percentage production during was higher in the lighted pen. With the exception of the first two weeks in, production was uniformly higher among the birds kept under lights. Both and White Hollands were used again in 1938, and in addition, pens were included which were heated as well as lighted. All night lights were used as in the two preceding years. These birds were compared with others which were in lighted but not heated pens, and, in the case of the, also with a pen which received neither light nor heat. However, an exceptionally mild winter was experienced, and 1--Total number of eggs per bud No Heat 56 Not Lighted 37.2 32.7 51.9 Heat 70.4 White Holland Lighted 41.1 No Heat 72.4 Not Lighted 28.0 the influence of the additional heat could not be expected to be as apparent as it might have been in more severe weather. The heated pens were maintained quite uniformly at 49 F. The percentage production is presented in Figure 1. In each case, the birds under lights, but without heat came into production somewhat earlier than those which were subjected to both light and heat, but both groups of pullets which were in the heated pen hit high peaks of production in which were not attained by any of the other pens at any time during the season. There was no decrease in production in the heated pens comparable to that reported by Lee and co-workers (1937) for chickens, but on the contrary, there was a sharp increase in the production of the in the heated pen. The total number of eggs produced per bird during the period of the experiment is presented in Table 1 for each of the four
THE USE OF ARTIFICIAL LIGHTS FOR TURKEYS 239 years. In each case the birds subjected to lights produced more eggs than those which were not lighted. FERTILITY AND HATCHABILITY The production of earlier eggs would be to no avail if this production did not result in a greater number of vigorous poults. that differences during the season might become apparent. In two years, 1936 and 1938, there was apparently lower fertility in the early eggs, but in both cases this was due to preferential mating. Those females which produced fertile eggs were found to exhibit normal fertility for those birds as judged by com- MAE. APE. MAY JUNE TOTAL FEB. MAR. APR.. MAY JUNE TOTAL FEB. MAE. APR. MAY JUNE TOTAL I ra n LESEND No Lights ^Lights t Heat H Lights Without Heat jfl No Lights, No Heat FIG. 2. Percentage fertility of turkey eggs Therefore, the percentages of fertility have been presented in Figure 2 on a monthly basis, and as totals for all of the eggs set from each pen. Similar figures for hatchability have been presented in Figure 3. If the lights exerted a deleterious effect upon either fertility or hatchability, this effect would be expected at the beginning of the laying season. Consequently, the data have been presented on a monthly basis in order m parison with later records, but certain females produced no fertile eggs whatever until later in the season. There is a possibility that such preferential mating might be eliminated by making up the mating some time prior to the actual beginning of the experiment. The hatchability figures for both 1937 and 1938 are extremely low, but this is undoubtedly due to faulty incubator opera-
240 H. L. WlLCKE tion and should not be attributed to the experimental variables because the hatchability for the lighted groups was, in most instances, higher than that from the unlighted groups. The effect of heat upon hatchability should be investigated further. In this work, heat apparently affected hatchability adversely in the egg from the as production on egg weight might be studied. These results are presented in Table 2. In 1936, the eggs produced in were decidedly smaller in the lighted pen, but this does not hold true for 1937 nor for 1938. The earlier eggs produced by the White Hollands in 1936 were smaller than those produced by the same birds later, but the eggs from this pen were fully MAR. APR. MAY JUNE TOTAL FE&. MAR. APE. MAY JUNE TOTAL FEB. MAR.APR. MAY JUNE TOTAL I Lights I N O Lights ] Lights + Heat H Lights Without Heat No Lights, No Heat compared with those from the White Hollands, but, since the numbers in each pen were small, no conclusions can be drawn from these data. EGG WEIGHTS Since egg size is an important factor in determining the size of the poult at hatching time, the egg weights were recorded by months in order that the effect of early FIG. 3. Percentage hatchability of turkey eggs. as large as those from the unlighted pen when those birds came into production in. From these results, it would seem that artificial lights exert little, if any, effect upon egg weight. These results are in agreement with those of Charles et al. (1937). While the data are limited, it is worthy of note that in both the and White Hollands, those birds which were subjected to heat, produced smaller eggs than the
THE USE OF ARTIFICIAL LIGHTS FOR TURKEYS 241 birds which received light but no heat. Although these birds were kept at much lower temperatures, the results indicate general agreement with those of Bennion and Warren (1933) who found that increases in temperatures decreased the size of the eggs produced. FEED CONSUMPTION Feed consumption records were kept for the last two years only. The figures for 1937 are presented in Table 3 and those for 1938 in Table 4. The feed consumption of the lighted and unlighted groups was January Total Total Total TABLE 2. Egg weights in grams 1936 80.9 85.0 86.3 86.2 84.8 88 83 90.3 93.4 88.7 Lights Lights Plus Heat 82.7 89.5 89.5 92.7 98.0 90.3 White Hollands 81.4 86.9 86.2 85.4 86.4 87.0 86.1 1937 White Holland 75.8 79 80.4 79.5 80.0 79.1 1938 No Lights 87.2 88.4 85.2 85 86.9 White Holland 83.9-84.9 88.3 89.4 86.7 Lights without Heat 86.3 87.4 87.2 89.8 88 87.9 White Holland 83.1 84 85.1 87.3 87.2 85.0 84.0 91.8 90.4 87.8 79.1 88 No Heat No Lights 86.8 90.1 87.1 89.4 89.1 88.5 TABLE 3. Feed consumption per bird in pounds 1937 Date Av. per Month Av. Total Feed per Month Mash 7.1 9.7 8.4 6.5 4.4 7.4 Lights 10.3 Grain 6.0 2.8 1.3 2.5 2.2 2.9 No Lights Mash 9.2 10.0 7.7 6.8 4.5 7 10.4 Grain 4.8 2.9 1.3 2.5 2.3 2.8 almost identically the same when calculated on a monthly basis per bird. While there are distinct differences in the type of feed consumed in the various pens in 1938, the total consumption was almost identical in the case of the, and approximately equal for the two lots of White Holland turkeys. There was a very heavy consumption of oyster shell in those lots which were subjected to both lights and heat, and these pens also consumed relatively greater quantities of mash in comparison with the groups which were not in heated pens. The total feed consumption in each case is somewhat less than that reported by Albright and Thompson (1933) but the 1938 feed consumption was in essential agreement with the figures presented by Marsden (1936). DISCUSSION The results obtained provide additional evidence that turkeys can be stimulated to earlier production by the use of artificial light, using either morning and evening lights or all night lights. While the length of time elapsing between the beginning of exposure to artificial lights and the production of the first egg varied from year to year and also with time of the year the lights were used, the time required to reach a level of approximately fifty percent pro-
242 H. L. WlLCKE duction appeared to be about six weeks, for three of the four years included in this experiment. The fact that very severe weather was encountered in 1936 very probably accounts for the failure of the birds to reach higher levels of production during the early part of that season. The data presented are not conclusive as to the effect of artificial lighting upon fertility, since in two years of the four there January Av. per month Av. total feed per month January Av. per month Av. total feed per month TABLE 4. Feed consumption per bird in pounds 1938 Mash Lights plus Heat Grain 7.7 4 7.8 4.4 6.7 4 7.2 3.8 7.2 5.0 7.2 5.0 7.3 4 7 7.8 6.7 7.2 7.2 7.2 7.3 13.0 4.8 4.4 4 4.3 5.0 4.4 4 12.85 was some evidence of lower fertility in the extremely early eggs. This was probably due to failure to mate, since the early fertility of some of the females was good, whereas no fertile eggs were produced by others. There is a possibility that this condition might exist in unlighted pens had the males been withheld until the same number of days prior to the onset of production. If flock matings had been used, or if the males had been rotated, the early fertility might be increased. These practices Shell 1.1 1.2 1.2 1.5.9 1.1 White Holland 1.0 1.2 1.0 1.1.8.7.95 were not followed because the poults produced were pedigreed for further use. It is very evident that the use of artificial light did not influence the total feed consumption of the turkeys in these experiments. The feed consumption per bird was remarkably uniform for the various lots used each of the two years. In 1937 there was a decline in feed consumption in and, which as in the results reported Lights without Heat Mash 4.7 5.1 4.8 6.9 6.9 5.5 5.7 5.7 5 4.9 7.0 7.0 7.0 6.1 Grain Shell 7.7 6.9.5 5.5 7.4 6.5.3 6.0.3 6.7.5 12.9 6.7 6.4 5 7.4 7.4 6.4 6.7 13.3.3.3.5 No Lights. No Heat Mash Grain Shell 4.3 7 4.1 7.4.4 4.9 5.8 7.0 7.4 7.0 7.4.3 4.1 7.4.3 5.2 7.2.5 12.9 by Scott and Payne (1937) occurred in the fourth and fifth month of the experiment. However, there was no such marked decline in the feed consumption of the birds in 1938, although there was evidence of decreased feed consumption in the sixth month of the experiment. SUMMARY The results of this work indicate: (1) That turkey females may be brought into production at an earlier date by the use
THE USE OF ARTIFICIAL LIGHTS FOR TURKEYS 243 of artificial lights, using either morning and evening or all-night lights. This is in agreement with reports from other stations. (2) The length of time elapsing between the date artificial lighting is initiated and the production of the first egg varies with the time of the year and to some degree with climatic conditions, but, in general, lights should be turned on approximately six weeks before a reasonably high level of production is desired, which in this work, was 40 to SO percent. (3) There is no evidence to show that either light or heat affect the fertility or hatchability of the eggs, although there was some evidence of preferential mating in the early eggs from certain pens. (4) The total production per bird for the period ending in was increased by the use of artificial lights. (5) Egg weight was apparently not affected by the use of artificial lights. (6) The total feed consumption per bird per month was not affected by the use of either lights or heat. (7) The feed consumption of the heated and non-heated birds differs quite markedly in the type of feed consumed. Since the numbers of birds were small, no definite conclusions can be drawn, but it is worthy of note that the birds in the heated pens consumed a much higher proportion of mash and much less grain than those birds which received no heat. REFERENCES Albright, W. P., and R. B. Thompson, 1933. Securing early turkeys by stimulated egg production. Poul Sci. 12:124-128., 1934. Morning lights increase egg production in turkeys. Rpt. Okla. Agr. Exp. Sta. 1932-1934, pp. 132-134. Anon, 1930. Turkey production. Neb. Agr. Exp. Sta. Ann. Rpt. p. 39. Bennion, Noel L., and D. C. Warren, 1933. Temperature and its effect on egg size in the domestic fowl. Poul. Sci. 12:69-82. Charles, T. B., P. A. Wilcox, D. W. Flagg, and A. E. Tepper, 1937. Confinement vs. open range for turkey breeders. N. H. Agr. Exp. Sta. Bui. 304:27-28. Lee, Clarence E., S. W. Hamilton, C. L. Henry, and M. E. Callanan, 1937. The effect of supplementary heat on egg production, feed consumption, amount of litter required and net flock income. Poul. Sci. 16:267-273. Marsden, S. J., 1936. Feed consumption and cost of feeding of turkey breeding stock. Poul. Sci. 15:400-404., 1936. A study of egg production in turkeys. Poul. Sci. 15:439-445. Moore, J. M., and A. M. Berridge, 1934. Michigan turkeys. Ext. Bui. 137. Mich. State College. Scott, H. M., and L. F. Payne, 1937. Light in relation to the experimental modification of the breeding season of turkeys. Poul. Sci. 16 :90-96.