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The Effect of Constant and Fluctuating Environmental Temperatures on the Biological Performance of Laying Pullets1
1562
J. C. ROGLER, H. E. PARKER,
F. N. ANDREWS AND C. W.
ACKNOWLED GMENTS The authors wish to gratefully acknowledge Dr. George M. Neher of the School of Veterinary Science and Medicine for the
photography involved in the photomicrographs. REFERENCES Creek, R. D., H. E. Parker, S. M. Hauge, F. N. Andrews and C. W. Carrick, 19SS. Unpublished data. Purdue Univ. Agr. Exp. Sta. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1959a. The effects of an iodine deficiency on embryo development and hatchability. Poultry Sci. 38: 398-405. Rogler, J. C , H. E, Parker, F. N. Andrews and C. W. Carrick, 19S9b. Various factors affecting the iodine-131 uptake of embryonic thyroids. Poultry Sci. 38: 405-410. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1961. The iodine requirements of the breeding hen. 1. Hens reared on a diet adequate in iodine. Poultry Sci. 40: 1546-1554.
The Effect of Constant and Fluctuating Environmental Temperatures on the Biological Performance of Laying Pullets1 W E R N E R J.
Department
MUELLER
of Poultry Husbandry, Pennsylvania State University, University Park, Pennsylvania (Received for publication January 23, 1961)
I
NVESTIGATIONS of the seasonal variation of egg production in different geographic locations (for reviews see Huston et al., 1957; Ragab and Assem, 1953) have led to the conclusion that high environmental temperature is one of the major causes of the decline in egg production during summer. In most of these studies it was difficult to separate the effect of age from the effect of the seasonally changing environment. The results of experiments with layers of the same age are less conclusive. Warren et al. (1950) found little difference in annual egg production between an uncon1 Authorized for publication on January 3, 1961 as paper No. 2515 in the journal series of the Pennsylvania Agricultural Experiment Station.
trolled environment, where the mean daily temperatures ranged from about 30°F. in winter to about 85°F. in summer, and a controlled environment where a constant temperature of 65°F. was maintained. Huston et al. (1957) reported that White Leghorn hens laid as well at a constant temperature of 90°F. as hens kept in an environment where mean daily temperatures ranged from 42.6°F. to 62.5°F. Squibb (1959) reported that there were no significant differences in egg production, feed consumption, mortality, body weight, and egg size, between hens housed in the tropical lowlands and hens housed in the cooler mountain areas of Guatemala. In a later experiment at New Brunswick, N.J., Squibb et al. (1959) found that White Leghorn hens housed in an environment where maxi-
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7. A direct relationship was obtained between iodine content of the dam's diet and the iodine content of the thyroids of embryos from these hens. 8. At the end of the experiment, there were no significant differences in thyroid size of the hens involved in these studies, although histological evidence of an iodine deficiency was apparent in hens on the lowest level of iodine (10-24 p.p.b.).
CARRICK
TEMPERATURE AND PERFORMANCE
EXPERIMENTAL FACILITIES AND PROCEDURE
The environmental facilities used in this experiment consist of three rooms, each 9' X 19' X 9' high, in which constant temperatures from 50°F. to 110°F. and constant relative humidities from 30% to 90% can be maintained within ±2.5°F. and ± 5 % , respectively. In addition, one of the
three rooms is equipped to cycle temperature and humidity within the limits mentioned above. In this case the tolerances are ± 5 ° F . for temperature and ± 1 0 % for relative humidity. The walls and ceilings of the three rooms are insulated with two inches of styrofoam. The conditioned air is supplied to each room through a 4' by 15' plenum whose bottom is covered with masonite pegboard with 5/16" holes drilled on 1" centers. Air is supplied to the plenum of each room at a rate of approximately 1400 CFM of which 80 CFM are outside air and the remainder recirculated air. Each room is illuminated with eight 100 watt frosted light bulbs. Average light intensity over the feed trough of the upper and lower deck is 11 and 26 international foot candles, respectively. During the experiment reported here the lights were on from 5 a.m. to 7 p.m. each day. Each room holds 48 layers in individual cages which are arranged in two decks with six inches of air space between decks. In 1958/59 two groups of 48 pullets each were kept at constant temperatures of 90°F. (group A) and 55°F. (group B), respectively. A third group of 48 pullets (group C) was kept in an environment where temperature cycled from 90°F. at 2 p.m. to 55°F. at 2 a.m. (Figure 1). During 1959/60 rooms A and B were kept at the same temperature as in 1958/59, while the temperature cycle in room C was reversed so that the maximum of 90°F. occurred at 2 a.m. and the minimum of 55°F. at 2 p.m. (Figure 1). In both years relative humidity was maintained at 70% in all three rooms. In both years a control group of 60 pullets was housed in a battery located in a pen (room D) where temperature and humidity were not controlled but recorded continuously. Figure 2 shows the 28-day averages of daily maximum and minimum temperatures in this room.
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mum temperatures reached 106°F. laid as well as hens housed in an environment where temperatures did not exceed 77°F. They concluded from these two experiments that wide diurnal temperature ranges may reduce the stress imposed on hens by extreme maximum temperatures. With the exception of Squibb's (1959) report there is agreement in the literature that high environmental temperatures reduce egg weight (Bennion and Warren, 1933; Skoglund et al., 1951; Hutchinson, 1953), shell thickness (Bennion and Warren, 1933; Warren and Schnepel, 1940; Mueller, 1959) and feed intake (Bennion and Warren, 1933; Bruckner, 1936; Lee etal., 1937,1939). Three rooms in which temperature and humidity can be controlled within narrow limits were constructed at The Pennsylvania State University in 1956. During the first experiment in 1957/58, which was designed to study the effect of environmental temperature on the calcium metabolism of laying hens (Mueller, 1959), it was observed that pullets kept in an uncontrolled environment laid more eggs than pullets kept at constant temperatures of 55°F. and 85°F., respectively. Based on this observation, as well as on oral reports of Squibb's (1959) results in Guatemala, it was decided to study the effect of constant and controlled cycling temperatures on egg production, mortality, feed consumption, body weight, egg weight, and shell quality.
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W. J. MUELLER TABLE 1.—Composition of the all-mash laying rations
9p/n. Midr night
.1958/59 . 1959/60 4am.
8am.
Noon 4p.m.
8pm.
FIG. 1. Daily temperature cycles in room C.
The same commercial strain of SingleComb White Leghorn pullets was used in both years. The 1958/59 pullets hatched on April 7, 1958 and were housed from range when they were 142 days old; the 1959/60 pullets hatched on May 18, 1959 and were housed when they were 147 days old. At housing time rooms A and B were kept at 70°F. and the temperature was raised or lowered 5°F. each day until the desired temperatures were reached. The pullets in room C were subjected to the temperature cycle mentioned above starting at housing time. In 1958/59 the pullets remained in the experiment until they were 486 days old; the 1959/60 experiment was terminated when the pullets were 435 days old. The composition of the all-mash laying rations is given in Table 1. During the entire 1958/59 experiment and up to March 9, 1960, all pullets were fed the ration containing 2.5% calcium. On March 9, 1960 the surviving pullets in each room were divided at random into two equal groups. One of the groups was continued on the ration containing 2.5% calcium while the other was fed the ration containing 3.9% calcium. Special feed troughs, which practically eliminated feed wastage, were used in the three controlled rooms. The feed troughs used in the uncontrolled environment D
3.9% calcium1
Pounds 685.2
Pounds 645.2
165 25 25 25 35
165 25 25 25
—
35 4 0.2
—
75 35 4 0.2
0.2
0.2
0.2
0.2
0.2
0.2
1,000.0
1,000.0
1
By calculation. Throughout the 1958/59 experiment and up to March 9, 1960. On March 9, 1960 replaced by calcite. 3 Granular calcium supplement #0853 A.F., Limestone Products Corporation of America. 2
were less satisfactory. Spot checks showed that feed wastage in this room amounted to about two per cent. There was a common feed trough for each four pullets in the three controlled environments and for each five pullets in the uncontrolled environment D. Feed consumption of each group of four or five pullets was determined at monthly intervals. The following egg quality measurements were obtained every second month in the 1958/59 experiment and up to March of the 1959/60 experiment: egg weight, shell weight, per cent shell, and shell thickness. After March 1960, these measurements were taken every month. In each test period eggs were collected from each pullet until two consecutive eggs had been obtained or ten days had elapsed. Egg weight and the weight of the washed and dried shells were determined to the closest one hundredth of a gram. Shell thickness was determined on three pieces of
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50
Ground yellow corn Soybean oil meal (44% protein) Fish meal (60% protein) Alfalfa meal, dehydrated Dried brewers yeast Ground3 limestone2 Calcite Steamed bonemeal Iodized Salt Manganese sulfate Riboflavin concentrate (8 mg. per gram) Stabilized vitamin A concentrate (10,000 I.U. per gram) D-activated animal sterol (3,000 I.C.U. per gram)
2.5% calcium1
TEMPERATURE AND PERFORMANCE TABLE 2.—Effect of environmental temperature on mortality, egg production, feed consumption and body weight of S. C. W. Leghorn pullets from 150 to 435 days of age Room1 B Percent mortality 1958/59 1959/60 Average
19 15 17
D
0 7 3
8 12 10
187 193 190
182 192 187
Average egg production per pullet housed 1958/59 131 175 185 1959/60 127 179 192 Average 129 177 188
172 174 173
Feed consumption per pullet 1958/59 0.19 1959/60 0.20 Average 0.19
(lb.) 0.24 0.25 0.24
0.25 0.27 0.26
Pounds feed per clozen eggs 1958/59 5.0 5.3 1959/60 5.4 5.4 Average 5.2 5.4
4.4 4.5 4.4
5.0 5.3 5.1
Average body wet %H (lb.) December 1959 3.9 March 1960 3.6 April 1960 3.9 June 1960 4.1 July 1960 4.1 Average 3.9
4.3 4.3 4.4 4.5 4.5 4.4
4.3 4.5 4.5 4.7 4.7 4.5
Average egg production of survivors 1958/59 141 175 1959/60 140 183 Average 140 179
per day 0.27 0.28 0.28
4.4 4.3 4.4 4.4 4.4 4.4
16.;
0.3
1
Room A: constant 90°F. Room B : constant 5 5 T . Room C: cycling from 55°F. to 90°F. Room D : uncontrolled. 2 Significant difference at 5 % level between averages for rooms.
shell (shell membrane included) from the equator of each egg. The average of these three measurements was taken as the shell thickness of the respective egg. The data were analyzed by analysis of variance. If this analysis indicated significant differences among group averages the differences between any two groups were tested with Tukey's method (Snedecor, 1956).
ferences among environments. Mortality. Mortality in the constant 55°F. environment (room B) as well as in the cycling environment (room C) was low in both years. The highest mortality occurred at a constant temperature of 90°F. (room A). Mortality in the uncontrolled environment (room D) was higher than in rooms B and C, but lower than in room A in both years. Post mortem examinations showed that the principal causes of mortality were reproductive disorders and visceral lymphomatosis. Egg production. The analysis of the egg production data was based on (a) percent production of survivors during subsequent 28-day periods and (b) total production of survivors from 150 to 435 days of age. In each of the two laying years there was little difference among the three cqntrolled environments in the age at which 50% production and maximum production were reached (Figures 3 and 4). In 1958/59 the pullets in room D reached maximum production about three weeks later than those in the controlled environments, while there was no such difference in 1959/60. Comparison of Figures 3 and 4 shows that the 1959/60 pullets reached 50% production about two weeks later than the 1958/59
RESULTS
The data on mortality, egg production, feed consumption and body weight are summarized in Table 2. To allow a comparison of the 1958/59 and 1959/60 data the presentation of the 1958/59 data is based on the performance to 435 days of age only. During the final 51 days of the 1958/59 experiment, which are not included in Table 2, there was practically no change in the dif-
23
27
31
35 39 43 47 51 55 AGE OF PULLETS IN WEEKS
59
63
67
FIG. 2. Twenty-eight day averages of maximum and minimum temperatures in the uncontrolled environment D.
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2 2 2
Significant Difference 2
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W. J. MUELLER OCT
NOV. DEC. JAN. FEB. MAR. APR. MAY
J I M JUL. AUG.
90-
23
ROOM A (Constant 90 F ) ROOM B C Constant 55" F ) ROOM CCCyclingl ROOM DC Uncontrolled)
27
31
35
39 43 47 51 55 59 AGE OF PULLETS IN WEEKS
63
67
FIG. 3. Twenty-eight day averages for percent egg production of survivors in 1958/59.
pullets. This difference was probably caused by the later hatching date in 1959/60. Statistical analysis of percent production during ^the first ten periods (28 days each) showed that pullets kept at a constant temperature of 90°F. produced significantly fewer eggs than the pullets in any'of the three other rooms. The pullets in the two variable environments, C and D, produced significantly more eggs than the pullets kept at a constant temperature of 55°F., while the difference in egg production between the cycling environment C and the uncontrolled environment D was not significant. Figures 3 and 4 show that these differences in egg production were due primarily to differences in percent production after the maximum had been reached. Environmental temperature had little effect on the rate at which maximum production was reached. The data on total egg production of survivors from 150 to 435 days of age (Table 2) show the same differences among rooms as the percent production data. Total egg production in room A was significantly lower than in the three other rooms. However, in contrast to the percent production data, the differences among the remaining environments were not significant at the 5% level. This discrepancy has to be at-
NOV. DEC. JAN.
23
FIG.
27
FEB. MAR. APR. MAY
31 35 39 43 47 51 AGE OF PULLETS IN WEEKS
JUN. JUL.
55
59
4. Twenty-eight day averages for percent production of survivors in 1959/60.
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. .
tributed to the fact that variation in total egg production within rooms and years was considerably larger than variation of egg production within rooms, periods, and years. On a pullet housed basis the differences among the three controlled environments were about the same as on a survivor basis. Due to higher mortality in the uncontrolled environment D, egg production per pullet housed in this room was lower than in the constant 55°F. room. Feed consumption and feed conversion. Pullets kept at a constant temperature of 90°F. consumed about one-third less feed than pullets kept at a constant temperature of 55°F. (Table 2). Feed consumption in the cycling environment was intermediate between rooms A and B. All differences were statistically significant at the 5% level or better. In view of the feed wastage problem in room D (see above) it is doubtful if there was any real difference in feed consumption between rooms C and D. Feed consumption in the uncontrolled environment, however, was higher than in room A and lower than in room B.
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TEMPERATURE AND PERFORMANCE
TABLE 3.—Effect
of environmental temperature on egg weight, shell thickness, and percent shell Shell Thickness, mm.
Egg Weight, gm. Month and Year A Oct. Dec. Feb. Apr. June Aug.
1958 1958 1959 1959 1959 1959
Average to June 1959 S.D.
1 2
D
A
B
C
D
1959 1960 1960 I960 1 1960
A
B
C
D
49.7 56.4 61.4 62.8 64.5 66.4
49.8 55.5 58.9 61.4 61.9 62.4
49.6 56.3 60.4 62.1 63.2 62.0
.399 .359 .365 .360 .366 .363
.418 .384 .398 .390 .397 .393
.420 .378 .391 .370 .378 .376
.395 .379 .386 .385 .368 .355
9.88 10.40 10.42 8.95 9.42 9.36 9.19 9.48 9.52 9.00 9.30 8.88 8.97 9.15 8.93 8.93 9.06 9.08
9.81 9.31 9.25 9.16 8.60 8.54
52.3
59.0
57.5
58.3
.370
.397
.387
.383
9.20
9.23
1.4
Average 1959/60 2
C
49.2 51.0 52.4 53.9 54.8 55.6
2
Nov. Jan. Mar. May July
S.D.
B
Percent Shell
0.009
9.55
9.42
0.18
47 .2 50.6 49.8 48 .6 57.2 54.4 48 .9 58.8 56.5 49 .7 64.4 59.5 49 .3 65.5 59.9
51.7 58.2 60.6 62.7 63.6
.353 .324 .319 .296 .281
.386 .373 .354 .354 .352
.388 .354 .348 .328 .333
.403 .363 .365 .340 .340
9.17 8.57 8.75 8.49 7.85
9.80 9.47 9.22 9.14 8.92
9.86 10.19 9.07 9.28 9.22 9.46 8.62 8.96 8.68 8.57
48. 7 59.3
59.4
.315
.364
.350
.362
8.57
9.31
9.09
56.0 1 .4
0.008
0. 17
Data for May and July of 1960 based on layers maintained on ration containing 2.5% calcium. Significant difference at 5% level between averages for rooms.
9.29
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caused the most rapid increase of egg weight as the pullets became older. As compared with this condition, cycling the temperature from SS°F. to 90°F. (room C) caused a moderate but significant decrease in the rate at which egg weight increased with advancing age. At a constant temperature of 90°F. (room A) egg weight increased very slowly and in both years the average egg weight was below the large egg (24 ounces per dozen) classification when the pullets were 435 days old. The increase of egg weight in the uncontrolled environment D was comparable to the increase in room B until the pullets were about 350 days old. Thereafter the increase in room D was slower and during the 1958/59 experiment egg weight decreased from June to August 1959. The slower increase of egg weight in room D during the latter part of the experiment may be attributed to the rise in environmental temperature (Fig. 2). Shell thickness. Table 3 shows some striking differences between the 1958/59
The feed conversion data (Table 2) show that despite considerably lower egg production at a constant temperature of 90°F., feed conversion in this room was slightly better than at a constant temperature of SS°F. This probably has to be attributed to a difference in energy requirement for maintenance between the constant 55°F. and the constant 90°F. environment. Feed consumption per dozen eggs was lowest in the controlled cycling environment. Due to the feed wastage problem mentioned above, the feed conversion data for room D are probably somewhat too high. Body weight. There were only small and insignificant differences between the average body weight of the pullets housed in rooms B, C, and D. As compared with these three environments, a constant temperature of 90°F. caused a significant decrease in body weight. Egg weight. Table 3 shows that of the three controlled environments tested, a constant temperature of SS°F. (room B)
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W. J. MUELLER
both laying years. The differences in percent shell among rooms were similar to the differences in shell thickness in both years. Interaction between calcium content of ration and environmental temperature. Petersen et al. (1959, 1960) reported that increasing the calcium content of the ration above 2.2% leads to a significant increase of shell quality as measured by the specific gravity method. These reports raised the question if feeding a diet with a higher calcium content might have altered the effect of environmental temperature on shell quality in the experiment reported here. Starting on March 9, 1960, half of the pullets in each room were fed a ration containing 3.9% calcium, while the other half was continued on the 2.5% calcium diet. Statistical analysis of the egg production, feed consumption, body weight and egg weight data for the four month period showed that the calcium level of the diet had no effect on these characteristics. Shell thickness and percent shell, on the other hand, were improved by raising the calcium content of the ration from 2.5% to 3.9% (Table 4). The differences between the two calcium levels were significant (5% level) in the three controlled environments, but not in room D. Table 4 shows that the improvement of shell quality was greatest in room A. However, the differences among the controlled environments were too small to allow a definite conclusion on whether there was interaction between calcium level and environmental temperature. It will also be noted that average shell thickness on the 3.9% calcium ration in room A was still lower than shell thickness on the 2.5% calcium ration in any of the three other environments. In interpreting the percent shell data, the effect of egg weight on this characteristic has to be considered. Simple calculation shows that an identical change in shell thickness will cause a greater change in per-
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and the 1959/60 experiment. The average shell thickness in all four environments was lower during 1959/60 than in 1958/59. During the 1958/59 experiment there was a marked drop in shell thickness from October to December of the pullet year, but thereafter, shell thickness in the three controlled environments remained relatively constant. This is in agreement with the results of the 1957/58 experiment reported in an earlier paper (Mueller, 1959). During the 1959/60 experiment, on the other hand, shell thickness in all environments decreased rather steadily from one test period to the other. These differences between the two experiments are difficult to explain. The composition of the experimental rations as well as the strain of chickens were the same in both years and the same temperatures and relative humidities were maintained in rooms A and B in both experiments. Despite these differences between the two experiments, environmental temperature had a similar effect on shell thickness in both years. Of the three controlled environments tested, a constant temperature of 55°F. (room B) assured the highest shell thickness. Cycling temperature between 55°F. and 90°F. (room C) caused a relatively small but significant decrease in shell thickness. In both years shell thickness was lowest at a constant temperature of 90°F. (room A). During 1958/59 shell thickness in the uncontrolled environment D was significantly lower than in room B. During 1959/60, on the other hand, the difference in shell thickness between rooms B and D was not significant. Percent shell. Average percent shell in all four environments was lower in 1959/60 than in 1958/59 (Table 3), confirming the shell thickness data. However, whereas shell thickness declined only in 1959/60 as the pullets became older, percent shell showed a continuous decline with advancing age in
TEMPERATURE AND PERFORMANCE TABLE 4.—Effect of calcium level on shell quality at different environmental temperatures
Month
Room
Calciumi level
%
A
B
C
Shell thickness, mm. .349 .329 .299 .362 .308 .335
D .346 .340
2.5 3.9
May
2.5 3.9
.296 .313
.354 .357
.328 .342
.340 .340
June
2.5 3.9
.294 .309
.360 .364
.330 .334
.343 .350
July
2.5 3.9
.281 .310
.352 .365
.333 .343
.340 .348
Average
2.5 3.9
.292 .310
.354 .362
.330 .338
.342 .344
.009
.008
.008
.008
S.D.1 April
2.5 3.9
Percent shell 8.38 9.13 8.71 8.82 9.57 8.92
9.06 8.98
May
2.5 3.9
8.49 8.87
9.14 9.37
8.62 9.00
8.96 8.91
June
2.5 3.9
7.94 8.66
9.00 9.21
8.62 8.65
8.66 8.86
July
2.5 3.9
7.85 8.49
8.92 9.21
8.68 8.85
8.57 9.89
Average
2.5 3.9
8.16 8.71
9.05 9.34
8.66 8.86
8.81 8.91
0.18
0.18
0.17
0.16
S.D.1
1 Significant difference between averages for two calcium levels.
cent shell if the egg is small than if the egg is large. The low egg weight in room A (Table 3) accounts at least in part for the relatively large increase of percent shell in this room as compared with rooms B and C. DISCUSSION A comparisons of rooms A and B shows that a constant temperature of 90°F. increased mortality and depressed egg production, feed intake, egg weight and shell quality as compared with a constant temperature of 55°F. Exposing the pullets for five hours daily to temperatures from 85 °F. to 90°F. (room C) did not depress body
weight and egg production if this exposure was offset by a period of lower environmental temperatures. In fact, the comparison of rooms B and C indicates that fluctuating daily temperatures may have had a stimulating effect on egg production. The higher egg production of survivors in the uncontrolled environment D, as compared with room B, supports this conclusion. The higher mortality in room D, as compared with rooms B and C, may have been caused by greater exposure to infections. Room D was located in an older building and was part of a row of 25 pens. The three controlled rooms, on the other hand, were relatively new and isolated. In addition, the air of each room was constantly circulated through a separate air conditioning unit where it was cleaned by passage through a metal filter and a screen of spray water. Similar results were obtained in room C during 1958/59 and 1959/60, although the maximum temperature occurred at 2 p.m. in the former and at 2 a.m. in the latter. Therefore, it is likely that any difference between room C and the two constant environments was caused by the daily temperature cycle and not by a particular temperature at a definite stage of egg formation. The causes of the reduction in shell quality at high environmental temperatures are still not definitely known. It has been shown in an earlier experiment (Mueller, 1959) that this reduction is not caused by the concomitant reduction of feed and calcium intake on an all-mash ration, since the lower calcium intake is offset by better calcium utilization. In the present experiment, increasing the calcium content of the ration from 2.5% to 3.9% caused a relatively small but significant improvement of shell quality in rooms A, B and C. However, this improvement occurred in all three controlled rooms and had little effect on the differences among rooms. Therefore, this evidence does not contra-
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April
1569
1S70
W. J. MUELLER
SUMMARY
The effect of three controlled and one uncontrolled environments on egg production, mortality, feed consumption, egg weight and shell quality of S.C.W. Leghorn pullets from 150 to 435 days of age was studied. A constant temperature of 90°F. increased mortality and depressed egg production, feed intake, egg weight and shell quality as compared with a constant temperature of 55°F. Pullets kept in an environment where temperature cycled from 55°F. to 90°F. and back to 55°F. every 24 hours produced more eggs than pullets kept at a constant temperature of 55°F. Egg weight and shell quality in the cycling environment were significantly lower than in the constant 55°F. environment, but significantly better than in the constant 90°F. environment. The relation of the temperature
cycle to the periods of light and dark had no, or only little effect on the biological performance of the pullets. Surviving pullets in the uncontrolled environment produced more eggs than those kept at a constant temperature of 55°F. Increasing the calcium content of the ration from 2.5% to 3.9% caused a small but significant increase of shell quality in the three controlled environments, while the increase in the uncontrolled environment was inconsistent and not significant. ACKNOWLEDGMENT
This investigation was supported in part by a research grant from the Cooperative Grange League Federation Exchange, Inc., Ithaca, N.Y. REFERENCES Bennion, N. L., and D. C. Warren, 1933. Temperature and its effect on egg size in the domestic fowl. Poultry Sci. 12: 69-82. Bruckner, J. H., 1936. The effect of environmental conditions on winter egg production. Poultry Sci. 15: 417-418. Huston, T. M., W. P. Joiner and J. L. Carmon, 1957. Breed differences in egg production of domestic fowl held at high environmental temperatures. Poultry Sci. 36: 1247-1254. Hutchinson, J. C. D., 1953. Effect of hot climates on egg weight. Poultry Sci. 32: 692-696. Lee, C. E., S. W. Hamilton, C. L. Henry and M. E. Callahan, 1937. The effect of supplementary heat on egg production, feed consumption, amount of litter required, and net flock income. Poultry Sci. 16: 267-273. Lee, C. E., S. W. Hamilton, C. L. Henry and M. E. Callahan, 1939. The effect of supplementary heat on egg production, feed consumption, amount of litter required, and net flock income—part 2. Poultry Sci. 18: 359-368. Mueller, W. J., 1959. The effect of environmental temperature and humidity on the calcium balance and serum calcium of laying pullets. Poultry Sci. 38 : 1296-1301. Petersen, C. F., E. A. Sauter, A. C. Wieser and D. H. Lumijarvi, 1959. Influence of calcium and other nutrients upon shell quality of high producing White Leghorn hens. Poultry Sci. 38: 1236.
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diet the previous conclusion (Mueller, 1959) that the reduction in calcium intake at high environmental temperatures is not, or only a minor cause of the concomitant reduction of shell quality. On the basis of the present experiment it is unlikely that the improvement of shell quality on the 3.9% calcium ration was due to the fact that the 2.5% calcium ration did not satisfy the long-term calcium requirements of the pullets. In May 1960, for example, only 2 1 % to 3 1 % of the monthly calcium intake supplied by the 2.5% ration was used for shell formation. This is well below the 50% retention reported by Mueller (1959) for a ration containing 2.3% calcium, and the 70% retention on a calcium intake of 0.5 grams per day, reported by Tyler and Wilcox (1942). It seems more likely that the improvement of shell quality on the 3.9% calcium ration was due to the higher calcium concentration in the intestines during actual shell formation, which facilitated the absorption of calcium during this period of peak demand.
TEMPERATURE AND PERFORMANCE
and feed efficiency of New Hampshire hens. J. Agric. Sci. 52 : 217-222. Squibb, R. L., G. N. Wogan and C. H. Reed, 1959. Production of White Leghorn hens subjected to high environmental temperatures with wide diurnal fluctuations. Poultry Sci. 38 : 11821183.
Tyler, C , and J. S. Wilcox, 1942. Calcium and phosphorus balances with laying birds. J. Agr. Sci. 32: 43-61. Warren, D. C , and R. L. Schnepel, 1940. The effect of air temperatures on egg shell thickness in the fowl. Poultry Sci. 19: 67-72. Warren, D. C , R. Conrad, A. E. Schumacher and T. B. Avery, 1950. Effects of fluctuating environment on laying hens. Kansas Ag. Exp. Sta. Tech. Bull. 68.
Studies on the Value of Hulless Barley in Chick Diets and Means of Increasing This Value1 J. O. ANDERSON, D. C. DOBSON AND R. K. WAGSTAFF Poultry Department, Utah State University, Logan, Utah (Received for publication January 26, 1961)
T
HE nutritional value of barley has long been recognized to be below that of corn for poultry. Generally the hull of the barley has been considered to be the main factor responsible for this lower value. The hull contains a high level of undigestible fiber. Through the efforts of agronomists at this station, a new variety of barley has been developed which loses its hull during the normal harvesting operations and showed promise of producing higher yields than the older varieties of hulless barley. Its appearance is much like that of wheat. The following values are typical of those obtained by chemical analysis of the hulless barley: ether extract, 1.5%; crude fiber, 2.2%; ash, 1.9%; protein (N X 6.25) 11.7%; calcium, 0.07%; and phosphorus,
1 Approved publication as Journal paper number 166, 1961 by Utah Agricultural Experiment Station.
0.4%. It was expected that the new hulless barley would be equal to wheat as a feed for poultry. A limited amount of hulless barley was made available for poultry experiments from the 1954 crop. The first experiments with chicks indicated that the feeding value of the hulless barley was less than that of corn, milo, or wheat, and that it was very little, if any, better than a heavy barley with a hull. Subsequent experiments confirmed this. Since then, several methods of increasing the value of diets containing high levels of this hulless barley have been studied. These include the addition of fat, enzyme supplements, or limited amounts of corn, or soaking the grain in water following the procedure of Fry et al. (1957), and other modifications of this procedure. This paper presents the results of these experiments.
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Petersen, C. F., D. H. Conrad, D. H. Lumijarvi, E. A. Sauter and C. E. Lampman, 1960. Studies on the calcium requirements of high producing White Leghorn hens. Idaho Ag. Exp. Sta. Res. Bull. 44. Ragab, M. T., and M. A. Assem, 1953. Effect of atmosphere temperature and daylight on egg weight and yield in Fayoumi and Baladi fowl. Poultry Sci. 32: 1021-1027. Skoglund, W. C , A. E. Tomhave and C. W. Mumford, 1951. Egg weight in New Hampshires hatched each month of the year. Poultry Sci. 30: 452-454. Snedecor, G. W., 1956. Statistical Methods. Iowa State College Press, Ames, Iowa. Squibb, R. L., 1959. Relation of diurnal temperature and humidity ranges to egg production
1571
J. C. ROGLER, H. E. PARKER,
F. N. ANDREWS AND C. W.
ACKNOWLED GMENTS The authors wish to gratefully acknowledge Dr. George M. Neher of the School of Veterinary Science and Medicine for the
photography involved in the photomicrographs. REFERENCES Creek, R. D., H. E. Parker, S. M. Hauge, F. N. Andrews and C. W. Carrick, 19SS. Unpublished data. Purdue Univ. Agr. Exp. Sta. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1959a. The effects of an iodine deficiency on embryo development and hatchability. Poultry Sci. 38: 398-405. Rogler, J. C , H. E, Parker, F. N. Andrews and C. W. Carrick, 19S9b. Various factors affecting the iodine-131 uptake of embryonic thyroids. Poultry Sci. 38: 405-410. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1961. The iodine requirements of the breeding hen. 1. Hens reared on a diet adequate in iodine. Poultry Sci. 40: 1546-1554.
The Effect of Constant and Fluctuating Environmental Temperatures on the Biological Performance of Laying Pullets1 W E R N E R J.
Department
MUELLER
of Poultry Husbandry, Pennsylvania State University, University Park, Pennsylvania (Received for publication January 23, 1961)
I
NVESTIGATIONS of the seasonal variation of egg production in different geographic locations (for reviews see Huston et al., 1957; Ragab and Assem, 1953) have led to the conclusion that high environmental temperature is one of the major causes of the decline in egg production during summer. In most of these studies it was difficult to separate the effect of age from the effect of the seasonally changing environment. The results of experiments with layers of the same age are less conclusive. Warren et al. (1950) found little difference in annual egg production between an uncon1 Authorized for publication on January 3, 1961 as paper No. 2515 in the journal series of the Pennsylvania Agricultural Experiment Station.
trolled environment, where the mean daily temperatures ranged from about 30°F. in winter to about 85°F. in summer, and a controlled environment where a constant temperature of 65°F. was maintained. Huston et al. (1957) reported that White Leghorn hens laid as well at a constant temperature of 90°F. as hens kept in an environment where mean daily temperatures ranged from 42.6°F. to 62.5°F. Squibb (1959) reported that there were no significant differences in egg production, feed consumption, mortality, body weight, and egg size, between hens housed in the tropical lowlands and hens housed in the cooler mountain areas of Guatemala. In a later experiment at New Brunswick, N.J., Squibb et al. (1959) found that White Leghorn hens housed in an environment where maxi-
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7. A direct relationship was obtained between iodine content of the dam's diet and the iodine content of the thyroids of embryos from these hens. 8. At the end of the experiment, there were no significant differences in thyroid size of the hens involved in these studies, although histological evidence of an iodine deficiency was apparent in hens on the lowest level of iodine (10-24 p.p.b.).
CARRICK
TEMPERATURE AND PERFORMANCE
EXPERIMENTAL FACILITIES AND PROCEDURE
The environmental facilities used in this experiment consist of three rooms, each 9' X 19' X 9' high, in which constant temperatures from 50°F. to 110°F. and constant relative humidities from 30% to 90% can be maintained within ±2.5°F. and ± 5 % , respectively. In addition, one of the
three rooms is equipped to cycle temperature and humidity within the limits mentioned above. In this case the tolerances are ± 5 ° F . for temperature and ± 1 0 % for relative humidity. The walls and ceilings of the three rooms are insulated with two inches of styrofoam. The conditioned air is supplied to each room through a 4' by 15' plenum whose bottom is covered with masonite pegboard with 5/16" holes drilled on 1" centers. Air is supplied to the plenum of each room at a rate of approximately 1400 CFM of which 80 CFM are outside air and the remainder recirculated air. Each room is illuminated with eight 100 watt frosted light bulbs. Average light intensity over the feed trough of the upper and lower deck is 11 and 26 international foot candles, respectively. During the experiment reported here the lights were on from 5 a.m. to 7 p.m. each day. Each room holds 48 layers in individual cages which are arranged in two decks with six inches of air space between decks. In 1958/59 two groups of 48 pullets each were kept at constant temperatures of 90°F. (group A) and 55°F. (group B), respectively. A third group of 48 pullets (group C) was kept in an environment where temperature cycled from 90°F. at 2 p.m. to 55°F. at 2 a.m. (Figure 1). During 1959/60 rooms A and B were kept at the same temperature as in 1958/59, while the temperature cycle in room C was reversed so that the maximum of 90°F. occurred at 2 a.m. and the minimum of 55°F. at 2 p.m. (Figure 1). In both years relative humidity was maintained at 70% in all three rooms. In both years a control group of 60 pullets was housed in a battery located in a pen (room D) where temperature and humidity were not controlled but recorded continuously. Figure 2 shows the 28-day averages of daily maximum and minimum temperatures in this room.
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mum temperatures reached 106°F. laid as well as hens housed in an environment where temperatures did not exceed 77°F. They concluded from these two experiments that wide diurnal temperature ranges may reduce the stress imposed on hens by extreme maximum temperatures. With the exception of Squibb's (1959) report there is agreement in the literature that high environmental temperatures reduce egg weight (Bennion and Warren, 1933; Skoglund et al., 1951; Hutchinson, 1953), shell thickness (Bennion and Warren, 1933; Warren and Schnepel, 1940; Mueller, 1959) and feed intake (Bennion and Warren, 1933; Bruckner, 1936; Lee etal., 1937,1939). Three rooms in which temperature and humidity can be controlled within narrow limits were constructed at The Pennsylvania State University in 1956. During the first experiment in 1957/58, which was designed to study the effect of environmental temperature on the calcium metabolism of laying hens (Mueller, 1959), it was observed that pullets kept in an uncontrolled environment laid more eggs than pullets kept at constant temperatures of 55°F. and 85°F., respectively. Based on this observation, as well as on oral reports of Squibb's (1959) results in Guatemala, it was decided to study the effect of constant and controlled cycling temperatures on egg production, mortality, feed consumption, body weight, egg weight, and shell quality.
1563
1564
W. J. MUELLER TABLE 1.—Composition of the all-mash laying rations
9p/n. Midr night
.1958/59 . 1959/60 4am.
8am.
Noon 4p.m.
8pm.
FIG. 1. Daily temperature cycles in room C.
The same commercial strain of SingleComb White Leghorn pullets was used in both years. The 1958/59 pullets hatched on April 7, 1958 and were housed from range when they were 142 days old; the 1959/60 pullets hatched on May 18, 1959 and were housed when they were 147 days old. At housing time rooms A and B were kept at 70°F. and the temperature was raised or lowered 5°F. each day until the desired temperatures were reached. The pullets in room C were subjected to the temperature cycle mentioned above starting at housing time. In 1958/59 the pullets remained in the experiment until they were 486 days old; the 1959/60 experiment was terminated when the pullets were 435 days old. The composition of the all-mash laying rations is given in Table 1. During the entire 1958/59 experiment and up to March 9, 1960, all pullets were fed the ration containing 2.5% calcium. On March 9, 1960 the surviving pullets in each room were divided at random into two equal groups. One of the groups was continued on the ration containing 2.5% calcium while the other was fed the ration containing 3.9% calcium. Special feed troughs, which practically eliminated feed wastage, were used in the three controlled rooms. The feed troughs used in the uncontrolled environment D
3.9% calcium1
Pounds 685.2
Pounds 645.2
165 25 25 25 35
165 25 25 25
—
35 4 0.2
—
75 35 4 0.2
0.2
0.2
0.2
0.2
0.2
0.2
1,000.0
1,000.0
1
By calculation. Throughout the 1958/59 experiment and up to March 9, 1960. On March 9, 1960 replaced by calcite. 3 Granular calcium supplement #0853 A.F., Limestone Products Corporation of America. 2
were less satisfactory. Spot checks showed that feed wastage in this room amounted to about two per cent. There was a common feed trough for each four pullets in the three controlled environments and for each five pullets in the uncontrolled environment D. Feed consumption of each group of four or five pullets was determined at monthly intervals. The following egg quality measurements were obtained every second month in the 1958/59 experiment and up to March of the 1959/60 experiment: egg weight, shell weight, per cent shell, and shell thickness. After March 1960, these measurements were taken every month. In each test period eggs were collected from each pullet until two consecutive eggs had been obtained or ten days had elapsed. Egg weight and the weight of the washed and dried shells were determined to the closest one hundredth of a gram. Shell thickness was determined on three pieces of
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50
Ground yellow corn Soybean oil meal (44% protein) Fish meal (60% protein) Alfalfa meal, dehydrated Dried brewers yeast Ground3 limestone2 Calcite Steamed bonemeal Iodized Salt Manganese sulfate Riboflavin concentrate (8 mg. per gram) Stabilized vitamin A concentrate (10,000 I.U. per gram) D-activated animal sterol (3,000 I.C.U. per gram)
2.5% calcium1
TEMPERATURE AND PERFORMANCE TABLE 2.—Effect of environmental temperature on mortality, egg production, feed consumption and body weight of S. C. W. Leghorn pullets from 150 to 435 days of age Room1 B Percent mortality 1958/59 1959/60 Average
19 15 17
D
0 7 3
8 12 10
187 193 190
182 192 187
Average egg production per pullet housed 1958/59 131 175 185 1959/60 127 179 192 Average 129 177 188
172 174 173
Feed consumption per pullet 1958/59 0.19 1959/60 0.20 Average 0.19
(lb.) 0.24 0.25 0.24
0.25 0.27 0.26
Pounds feed per clozen eggs 1958/59 5.0 5.3 1959/60 5.4 5.4 Average 5.2 5.4
4.4 4.5 4.4
5.0 5.3 5.1
Average body wet %H (lb.) December 1959 3.9 March 1960 3.6 April 1960 3.9 June 1960 4.1 July 1960 4.1 Average 3.9
4.3 4.3 4.4 4.5 4.5 4.4
4.3 4.5 4.5 4.7 4.7 4.5
Average egg production of survivors 1958/59 141 175 1959/60 140 183 Average 140 179
per day 0.27 0.28 0.28
4.4 4.3 4.4 4.4 4.4 4.4
16.;
0.3
1
Room A: constant 90°F. Room B : constant 5 5 T . Room C: cycling from 55°F. to 90°F. Room D : uncontrolled. 2 Significant difference at 5 % level between averages for rooms.
shell (shell membrane included) from the equator of each egg. The average of these three measurements was taken as the shell thickness of the respective egg. The data were analyzed by analysis of variance. If this analysis indicated significant differences among group averages the differences between any two groups were tested with Tukey's method (Snedecor, 1956).
ferences among environments. Mortality. Mortality in the constant 55°F. environment (room B) as well as in the cycling environment (room C) was low in both years. The highest mortality occurred at a constant temperature of 90°F. (room A). Mortality in the uncontrolled environment (room D) was higher than in rooms B and C, but lower than in room A in both years. Post mortem examinations showed that the principal causes of mortality were reproductive disorders and visceral lymphomatosis. Egg production. The analysis of the egg production data was based on (a) percent production of survivors during subsequent 28-day periods and (b) total production of survivors from 150 to 435 days of age. In each of the two laying years there was little difference among the three cqntrolled environments in the age at which 50% production and maximum production were reached (Figures 3 and 4). In 1958/59 the pullets in room D reached maximum production about three weeks later than those in the controlled environments, while there was no such difference in 1959/60. Comparison of Figures 3 and 4 shows that the 1959/60 pullets reached 50% production about two weeks later than the 1958/59
RESULTS
The data on mortality, egg production, feed consumption and body weight are summarized in Table 2. To allow a comparison of the 1958/59 and 1959/60 data the presentation of the 1958/59 data is based on the performance to 435 days of age only. During the final 51 days of the 1958/59 experiment, which are not included in Table 2, there was practically no change in the dif-
23
27
31
35 39 43 47 51 55 AGE OF PULLETS IN WEEKS
59
63
67
FIG. 2. Twenty-eight day averages of maximum and minimum temperatures in the uncontrolled environment D.
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2 2 2
Significant Difference 2
1565
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W. J. MUELLER OCT
NOV. DEC. JAN. FEB. MAR. APR. MAY
J I M JUL. AUG.
90-
23
ROOM A (Constant 90 F ) ROOM B C Constant 55" F ) ROOM CCCyclingl ROOM DC Uncontrolled)
27
31
35
39 43 47 51 55 59 AGE OF PULLETS IN WEEKS
63
67
FIG. 3. Twenty-eight day averages for percent egg production of survivors in 1958/59.
pullets. This difference was probably caused by the later hatching date in 1959/60. Statistical analysis of percent production during ^the first ten periods (28 days each) showed that pullets kept at a constant temperature of 90°F. produced significantly fewer eggs than the pullets in any'of the three other rooms. The pullets in the two variable environments, C and D, produced significantly more eggs than the pullets kept at a constant temperature of 55°F., while the difference in egg production between the cycling environment C and the uncontrolled environment D was not significant. Figures 3 and 4 show that these differences in egg production were due primarily to differences in percent production after the maximum had been reached. Environmental temperature had little effect on the rate at which maximum production was reached. The data on total egg production of survivors from 150 to 435 days of age (Table 2) show the same differences among rooms as the percent production data. Total egg production in room A was significantly lower than in the three other rooms. However, in contrast to the percent production data, the differences among the remaining environments were not significant at the 5% level. This discrepancy has to be at-
NOV. DEC. JAN.
23
FIG.
27
FEB. MAR. APR. MAY
31 35 39 43 47 51 AGE OF PULLETS IN WEEKS
JUN. JUL.
55
59
4. Twenty-eight day averages for percent production of survivors in 1959/60.
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. .
tributed to the fact that variation in total egg production within rooms and years was considerably larger than variation of egg production within rooms, periods, and years. On a pullet housed basis the differences among the three controlled environments were about the same as on a survivor basis. Due to higher mortality in the uncontrolled environment D, egg production per pullet housed in this room was lower than in the constant 55°F. room. Feed consumption and feed conversion. Pullets kept at a constant temperature of 90°F. consumed about one-third less feed than pullets kept at a constant temperature of 55°F. (Table 2). Feed consumption in the cycling environment was intermediate between rooms A and B. All differences were statistically significant at the 5% level or better. In view of the feed wastage problem in room D (see above) it is doubtful if there was any real difference in feed consumption between rooms C and D. Feed consumption in the uncontrolled environment, however, was higher than in room A and lower than in room B.
1567
TEMPERATURE AND PERFORMANCE
TABLE 3.—Effect
of environmental temperature on egg weight, shell thickness, and percent shell Shell Thickness, mm.
Egg Weight, gm. Month and Year A Oct. Dec. Feb. Apr. June Aug.
1958 1958 1959 1959 1959 1959
Average to June 1959 S.D.
1 2
D
A
B
C
D
1959 1960 1960 I960 1 1960
A
B
C
D
49.7 56.4 61.4 62.8 64.5 66.4
49.8 55.5 58.9 61.4 61.9 62.4
49.6 56.3 60.4 62.1 63.2 62.0
.399 .359 .365 .360 .366 .363
.418 .384 .398 .390 .397 .393
.420 .378 .391 .370 .378 .376
.395 .379 .386 .385 .368 .355
9.88 10.40 10.42 8.95 9.42 9.36 9.19 9.48 9.52 9.00 9.30 8.88 8.97 9.15 8.93 8.93 9.06 9.08
9.81 9.31 9.25 9.16 8.60 8.54
52.3
59.0
57.5
58.3
.370
.397
.387
.383
9.20
9.23
1.4
Average 1959/60 2
C
49.2 51.0 52.4 53.9 54.8 55.6
2
Nov. Jan. Mar. May July
S.D.
B
Percent Shell
0.009
9.55
9.42
0.18
47 .2 50.6 49.8 48 .6 57.2 54.4 48 .9 58.8 56.5 49 .7 64.4 59.5 49 .3 65.5 59.9
51.7 58.2 60.6 62.7 63.6
.353 .324 .319 .296 .281
.386 .373 .354 .354 .352
.388 .354 .348 .328 .333
.403 .363 .365 .340 .340
9.17 8.57 8.75 8.49 7.85
9.80 9.47 9.22 9.14 8.92
9.86 10.19 9.07 9.28 9.22 9.46 8.62 8.96 8.68 8.57
48. 7 59.3
59.4
.315
.364
.350
.362
8.57
9.31
9.09
56.0 1 .4
0.008
0. 17
Data for May and July of 1960 based on layers maintained on ration containing 2.5% calcium. Significant difference at 5% level between averages for rooms.
9.29
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caused the most rapid increase of egg weight as the pullets became older. As compared with this condition, cycling the temperature from SS°F. to 90°F. (room C) caused a moderate but significant decrease in the rate at which egg weight increased with advancing age. At a constant temperature of 90°F. (room A) egg weight increased very slowly and in both years the average egg weight was below the large egg (24 ounces per dozen) classification when the pullets were 435 days old. The increase of egg weight in the uncontrolled environment D was comparable to the increase in room B until the pullets were about 350 days old. Thereafter the increase in room D was slower and during the 1958/59 experiment egg weight decreased from June to August 1959. The slower increase of egg weight in room D during the latter part of the experiment may be attributed to the rise in environmental temperature (Fig. 2). Shell thickness. Table 3 shows some striking differences between the 1958/59
The feed conversion data (Table 2) show that despite considerably lower egg production at a constant temperature of 90°F., feed conversion in this room was slightly better than at a constant temperature of SS°F. This probably has to be attributed to a difference in energy requirement for maintenance between the constant 55°F. and the constant 90°F. environment. Feed consumption per dozen eggs was lowest in the controlled cycling environment. Due to the feed wastage problem mentioned above, the feed conversion data for room D are probably somewhat too high. Body weight. There were only small and insignificant differences between the average body weight of the pullets housed in rooms B, C, and D. As compared with these three environments, a constant temperature of 90°F. caused a significant decrease in body weight. Egg weight. Table 3 shows that of the three controlled environments tested, a constant temperature of SS°F. (room B)
1568
W. J. MUELLER
both laying years. The differences in percent shell among rooms were similar to the differences in shell thickness in both years. Interaction between calcium content of ration and environmental temperature. Petersen et al. (1959, 1960) reported that increasing the calcium content of the ration above 2.2% leads to a significant increase of shell quality as measured by the specific gravity method. These reports raised the question if feeding a diet with a higher calcium content might have altered the effect of environmental temperature on shell quality in the experiment reported here. Starting on March 9, 1960, half of the pullets in each room were fed a ration containing 3.9% calcium, while the other half was continued on the 2.5% calcium diet. Statistical analysis of the egg production, feed consumption, body weight and egg weight data for the four month period showed that the calcium level of the diet had no effect on these characteristics. Shell thickness and percent shell, on the other hand, were improved by raising the calcium content of the ration from 2.5% to 3.9% (Table 4). The differences between the two calcium levels were significant (5% level) in the three controlled environments, but not in room D. Table 4 shows that the improvement of shell quality was greatest in room A. However, the differences among the controlled environments were too small to allow a definite conclusion on whether there was interaction between calcium level and environmental temperature. It will also be noted that average shell thickness on the 3.9% calcium ration in room A was still lower than shell thickness on the 2.5% calcium ration in any of the three other environments. In interpreting the percent shell data, the effect of egg weight on this characteristic has to be considered. Simple calculation shows that an identical change in shell thickness will cause a greater change in per-
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and the 1959/60 experiment. The average shell thickness in all four environments was lower during 1959/60 than in 1958/59. During the 1958/59 experiment there was a marked drop in shell thickness from October to December of the pullet year, but thereafter, shell thickness in the three controlled environments remained relatively constant. This is in agreement with the results of the 1957/58 experiment reported in an earlier paper (Mueller, 1959). During the 1959/60 experiment, on the other hand, shell thickness in all environments decreased rather steadily from one test period to the other. These differences between the two experiments are difficult to explain. The composition of the experimental rations as well as the strain of chickens were the same in both years and the same temperatures and relative humidities were maintained in rooms A and B in both experiments. Despite these differences between the two experiments, environmental temperature had a similar effect on shell thickness in both years. Of the three controlled environments tested, a constant temperature of 55°F. (room B) assured the highest shell thickness. Cycling temperature between 55°F. and 90°F. (room C) caused a relatively small but significant decrease in shell thickness. In both years shell thickness was lowest at a constant temperature of 90°F. (room A). During 1958/59 shell thickness in the uncontrolled environment D was significantly lower than in room B. During 1959/60, on the other hand, the difference in shell thickness between rooms B and D was not significant. Percent shell. Average percent shell in all four environments was lower in 1959/60 than in 1958/59 (Table 3), confirming the shell thickness data. However, whereas shell thickness declined only in 1959/60 as the pullets became older, percent shell showed a continuous decline with advancing age in
TEMPERATURE AND PERFORMANCE TABLE 4.—Effect of calcium level on shell quality at different environmental temperatures
Month
Room
Calciumi level
%
A
B
C
Shell thickness, mm. .349 .329 .299 .362 .308 .335
D .346 .340
2.5 3.9
May
2.5 3.9
.296 .313
.354 .357
.328 .342
.340 .340
June
2.5 3.9
.294 .309
.360 .364
.330 .334
.343 .350
July
2.5 3.9
.281 .310
.352 .365
.333 .343
.340 .348
Average
2.5 3.9
.292 .310
.354 .362
.330 .338
.342 .344
.009
.008
.008
.008
S.D.1 April
2.5 3.9
Percent shell 8.38 9.13 8.71 8.82 9.57 8.92
9.06 8.98
May
2.5 3.9
8.49 8.87
9.14 9.37
8.62 9.00
8.96 8.91
June
2.5 3.9
7.94 8.66
9.00 9.21
8.62 8.65
8.66 8.86
July
2.5 3.9
7.85 8.49
8.92 9.21
8.68 8.85
8.57 9.89
Average
2.5 3.9
8.16 8.71
9.05 9.34
8.66 8.86
8.81 8.91
0.18
0.18
0.17
0.16
S.D.1
1 Significant difference between averages for two calcium levels.
cent shell if the egg is small than if the egg is large. The low egg weight in room A (Table 3) accounts at least in part for the relatively large increase of percent shell in this room as compared with rooms B and C. DISCUSSION A comparisons of rooms A and B shows that a constant temperature of 90°F. increased mortality and depressed egg production, feed intake, egg weight and shell quality as compared with a constant temperature of 55°F. Exposing the pullets for five hours daily to temperatures from 85 °F. to 90°F. (room C) did not depress body
weight and egg production if this exposure was offset by a period of lower environmental temperatures. In fact, the comparison of rooms B and C indicates that fluctuating daily temperatures may have had a stimulating effect on egg production. The higher egg production of survivors in the uncontrolled environment D, as compared with room B, supports this conclusion. The higher mortality in room D, as compared with rooms B and C, may have been caused by greater exposure to infections. Room D was located in an older building and was part of a row of 25 pens. The three controlled rooms, on the other hand, were relatively new and isolated. In addition, the air of each room was constantly circulated through a separate air conditioning unit where it was cleaned by passage through a metal filter and a screen of spray water. Similar results were obtained in room C during 1958/59 and 1959/60, although the maximum temperature occurred at 2 p.m. in the former and at 2 a.m. in the latter. Therefore, it is likely that any difference between room C and the two constant environments was caused by the daily temperature cycle and not by a particular temperature at a definite stage of egg formation. The causes of the reduction in shell quality at high environmental temperatures are still not definitely known. It has been shown in an earlier experiment (Mueller, 1959) that this reduction is not caused by the concomitant reduction of feed and calcium intake on an all-mash ration, since the lower calcium intake is offset by better calcium utilization. In the present experiment, increasing the calcium content of the ration from 2.5% to 3.9% caused a relatively small but significant improvement of shell quality in rooms A, B and C. However, this improvement occurred in all three controlled rooms and had little effect on the differences among rooms. Therefore, this evidence does not contra-
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April
1569
1S70
W. J. MUELLER
SUMMARY
The effect of three controlled and one uncontrolled environments on egg production, mortality, feed consumption, egg weight and shell quality of S.C.W. Leghorn pullets from 150 to 435 days of age was studied. A constant temperature of 90°F. increased mortality and depressed egg production, feed intake, egg weight and shell quality as compared with a constant temperature of 55°F. Pullets kept in an environment where temperature cycled from 55°F. to 90°F. and back to 55°F. every 24 hours produced more eggs than pullets kept at a constant temperature of 55°F. Egg weight and shell quality in the cycling environment were significantly lower than in the constant 55°F. environment, but significantly better than in the constant 90°F. environment. The relation of the temperature
cycle to the periods of light and dark had no, or only little effect on the biological performance of the pullets. Surviving pullets in the uncontrolled environment produced more eggs than those kept at a constant temperature of 55°F. Increasing the calcium content of the ration from 2.5% to 3.9% caused a small but significant increase of shell quality in the three controlled environments, while the increase in the uncontrolled environment was inconsistent and not significant. ACKNOWLEDGMENT
This investigation was supported in part by a research grant from the Cooperative Grange League Federation Exchange, Inc., Ithaca, N.Y. REFERENCES Bennion, N. L., and D. C. Warren, 1933. Temperature and its effect on egg size in the domestic fowl. Poultry Sci. 12: 69-82. Bruckner, J. H., 1936. The effect of environmental conditions on winter egg production. Poultry Sci. 15: 417-418. Huston, T. M., W. P. Joiner and J. L. Carmon, 1957. Breed differences in egg production of domestic fowl held at high environmental temperatures. Poultry Sci. 36: 1247-1254. Hutchinson, J. C. D., 1953. Effect of hot climates on egg weight. Poultry Sci. 32: 692-696. Lee, C. E., S. W. Hamilton, C. L. Henry and M. E. Callahan, 1937. The effect of supplementary heat on egg production, feed consumption, amount of litter required, and net flock income. Poultry Sci. 16: 267-273. Lee, C. E., S. W. Hamilton, C. L. Henry and M. E. Callahan, 1939. The effect of supplementary heat on egg production, feed consumption, amount of litter required, and net flock income—part 2. Poultry Sci. 18: 359-368. Mueller, W. J., 1959. The effect of environmental temperature and humidity on the calcium balance and serum calcium of laying pullets. Poultry Sci. 38 : 1296-1301. Petersen, C. F., E. A. Sauter, A. C. Wieser and D. H. Lumijarvi, 1959. Influence of calcium and other nutrients upon shell quality of high producing White Leghorn hens. Poultry Sci. 38: 1236.
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diet the previous conclusion (Mueller, 1959) that the reduction in calcium intake at high environmental temperatures is not, or only a minor cause of the concomitant reduction of shell quality. On the basis of the present experiment it is unlikely that the improvement of shell quality on the 3.9% calcium ration was due to the fact that the 2.5% calcium ration did not satisfy the long-term calcium requirements of the pullets. In May 1960, for example, only 2 1 % to 3 1 % of the monthly calcium intake supplied by the 2.5% ration was used for shell formation. This is well below the 50% retention reported by Mueller (1959) for a ration containing 2.3% calcium, and the 70% retention on a calcium intake of 0.5 grams per day, reported by Tyler and Wilcox (1942). It seems more likely that the improvement of shell quality on the 3.9% calcium ration was due to the higher calcium concentration in the intestines during actual shell formation, which facilitated the absorption of calcium during this period of peak demand.
TEMPERATURE AND PERFORMANCE
and feed efficiency of New Hampshire hens. J. Agric. Sci. 52 : 217-222. Squibb, R. L., G. N. Wogan and C. H. Reed, 1959. Production of White Leghorn hens subjected to high environmental temperatures with wide diurnal fluctuations. Poultry Sci. 38 : 11821183.
Tyler, C , and J. S. Wilcox, 1942. Calcium and phosphorus balances with laying birds. J. Agr. Sci. 32: 43-61. Warren, D. C , and R. L. Schnepel, 1940. The effect of air temperatures on egg shell thickness in the fowl. Poultry Sci. 19: 67-72. Warren, D. C , R. Conrad, A. E. Schumacher and T. B. Avery, 1950. Effects of fluctuating environment on laying hens. Kansas Ag. Exp. Sta. Tech. Bull. 68.
Studies on the Value of Hulless Barley in Chick Diets and Means of Increasing This Value1 J. O. ANDERSON, D. C. DOBSON AND R. K. WAGSTAFF Poultry Department, Utah State University, Logan, Utah (Received for publication January 26, 1961)
T
HE nutritional value of barley has long been recognized to be below that of corn for poultry. Generally the hull of the barley has been considered to be the main factor responsible for this lower value. The hull contains a high level of undigestible fiber. Through the efforts of agronomists at this station, a new variety of barley has been developed which loses its hull during the normal harvesting operations and showed promise of producing higher yields than the older varieties of hulless barley. Its appearance is much like that of wheat. The following values are typical of those obtained by chemical analysis of the hulless barley: ether extract, 1.5%; crude fiber, 2.2%; ash, 1.9%; protein (N X 6.25) 11.7%; calcium, 0.07%; and phosphorus,
1 Approved publication as Journal paper number 166, 1961 by Utah Agricultural Experiment Station.
0.4%. It was expected that the new hulless barley would be equal to wheat as a feed for poultry. A limited amount of hulless barley was made available for poultry experiments from the 1954 crop. The first experiments with chicks indicated that the feeding value of the hulless barley was less than that of corn, milo, or wheat, and that it was very little, if any, better than a heavy barley with a hull. Subsequent experiments confirmed this. Since then, several methods of increasing the value of diets containing high levels of this hulless barley have been studied. These include the addition of fat, enzyme supplements, or limited amounts of corn, or soaking the grain in water following the procedure of Fry et al. (1957), and other modifications of this procedure. This paper presents the results of these experiments.
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Petersen, C. F., D. H. Conrad, D. H. Lumijarvi, E. A. Sauter and C. E. Lampman, 1960. Studies on the calcium requirements of high producing White Leghorn hens. Idaho Ag. Exp. Sta. Res. Bull. 44. Ragab, M. T., and M. A. Assem, 1953. Effect of atmosphere temperature and daylight on egg weight and yield in Fayoumi and Baladi fowl. Poultry Sci. 32: 1021-1027. Skoglund, W. C , A. E. Tomhave and C. W. Mumford, 1951. Egg weight in New Hampshires hatched each month of the year. Poultry Sci. 30: 452-454. Snedecor, G. W., 1956. Statistical Methods. Iowa State College Press, Ames, Iowa. Squibb, R. L., 1959. Relation of diurnal temperature and humidity ranges to egg production
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