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The Adaptability of Chickens to Various Temperatures1
ARTIFICIAL INSEMINATION OF THE QUAIL
uterus. The distention of the uterus did not permit the complete uptake of the semen. It, therefore, seemed likely that this would have an adverse effect on fertility. Evidence that this is not the case is presented in Table 2. The fertility levels of birds having a hard shell egg were comparable to those having already laid.
result of lack of technique rather than bacterial infection as previously suggested by Wentworth and Mellen (1963). The described technique resulted in no infection or mortality and did not depress egg production. Additional data regarding time of insemination, volume of semen per insemination, diluents, etc. are currently being collected. A later paper will provide information on refinements which will hopefully increase present fertility levels. REFERENCES Burrows, W. H., and J. P. Quinn, 1939. Artificial insemination of chickens and turkeys. U.S.D.A. Circular 525. Ogasawara, F. X., and R. Huang, 1963. A modified method of artificial insemination in the production of chicken-quail hybrids. Poultry Sci. 42: 1386-1392. Wentworth, B. C , and W. J. Mellen, 1963. Egg production and fertility following various methods of insemination of Japanese quail. J. Reprod. Fertil. 6: 215-220. Wilson, W. O., U. K. Abbott and H. Abplanalp, 1961. Evaluation of Coturnix (Japanese quail) as pilot animal for poultry. Poultry Sci. 40: 651-657.
The Adaptability of Chickens to Various Temperatures 1 C. E. CLARK AND M. AMIN 2 Poultry Department, Utah State University, Logan, Utah (Received for publication December 17, 1964)
C
HICKENS deviate from their potential in reproductive performance when challenged by environmental conditions. Prolonged exposure to temperatures above 90°F. (Mueller, 1961) or below 1
Approved as Utah Agricultural Experiment Station Journal Paper No. 443. 2 Present Address: Karadj College, University of Tehran, Tehran, Iran.
60°F. (Hays, 1958) results in a reduced egg yield. Eggs produced under high air temperature conditions have thinner than normal shells and as a result are particularly fragile (Thornton and Moreng, 1959). These relationships are economically significant to the egg industry since meteorological variations constitute hazards in many poultry producing areas of the world.
Downloaded from http://ps.oxfordjournals.org/ at Library of Medical Center of Fudan University on May 9, 2015
DISCUSSION Although it is necessary that attempts be made to improve the fertility levels reported herein, it appears that this method provides a practical technique which will yield good results. Equal, if not superior results, to the laborious technique reported by Wentworth and Mellen (1963) were obtained. Fertility in 83 percent of birds inseminated compares favorably with the 77.5 percent figure reported by these workers. It is difficult to compare the two methods regarding fertility of total eggs since this value was not reported by Wentworth and Mellen. This study indicates that the inability to obtain satisfactory fertility levels from artificial insemination in Coturnix is the
1003
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C. E. CLARK AND M. AMIN
MATERIALS AND METHODS
Hatching eggs from four White Leghorn-type strains were obtained from university experiment stations in Wyoming (WYO), New Mexico (NM), and Oregon; (OA) indicates Oregon hybrid, and (OB) Oregon pure strain. These strains had been developed over a period of several years at their respective locations and thus each had been subject to unique conditions of altitude and temperature. Conditions at the various stations include: Wyoming at a 7250-foot elevation with a relatively cool temperature; New Mexico at about a 3900foot elevation with a warm temperature; Oregon at about a 240 foot elevation with a moderate temperature. Mean temperature differences are about 25°F. between the Wyoming and New Mexico stations. Eggs from a fifth strain were from commercial hybrid stock (AIC). Chicks from all strains were hatched together at Logan, Utah, intermingled until 17 weeks of age, and then transferred to individual cages located inside three rooms. The temperature regimes in two rooms of a windowless house consisted of 70-100° ± 3°F., and 65° ± 5°F. constant, respectively. The 70-100°F. regime fluctuated diurnally on the basis of a controlled program which specified 100°F. from 9:00
A.M. to 6:00 P.M. 70°F. from 12:00 midto 3:00 A.M. Six hours were allowed for the transition from 100°F. to 70°F. and vice versa. The third environment utilized a conventional-type poultry building wherein no set temperature was maintained and only factors contributed by animal heat, structural insulation, and mechanical ventilation were operative. Monthly mean temperatures, derived from averages of daily minimums and maximums recorded inside the "uncontrolled" house were: 55°F., November; 50°F., December; 45°F., January; 47°F., February; 54°F., March; 58°F., April; 72°F., May; 73°F., June. Fourteen hours of light were provided in the controlled environments. Daylight simply was not excluded in the "uncontrolled" house. One hundred-eighty pullets were arranged systematically in each of the three environments. Five birds constituted a unit and eight units were established for each of the strains: WYO, NM, and AIC. Six units were established for OA and six for OB. An all-mash laying ration was fed ad libitum with no nutritional variables, and continuously running water was provided. Observations were made over nine-2 8-day periods on eggs produced, egg weights, Haugh units, egg shell thicknesses, and percent shell values. A necropsy was performed on all birds that died. Egg shell and interior quality determinations were made from the mean value of two randomly selected eggs from each experimental unit. Egg shell thickness was determined on dried shells with membranes removed. The average of four thickness measurements (two sides and two ends) was recorded as shell thickness. The data were processed through techniques of analysis of variance and Duncan's new multiple range test (1955).
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There is evidence that genetic differences affect the sensitivity and adaptability of chickens to high environmental temperatures. This appears to be true between breeds (Huston et al., 19S7; Campos et al., 1960) and between families (Kheireldin and Shaffner, 1957). Individuals in a family have also demonstrated differences in acclimatization to hot humid environments (Hutchinson and Sykes, 1953). Genetic-environmental relationships with respect to adaptation of strains to different climates are reported here.
1005
ENVIRONMENTAL ADAPTATION RESULTS
TABLE 1.—Influence of ambient temperature on number of eggs produced Temperature
Mean % Hen-day eggs1
65°F. 70-100°F. "uncontrolled"
52.7" 45.5 b 52.1-
1 Data with different superscripts are significantly different at the one percent level according to Duncan's multiple range test (1955).
TABLE 2.—Strain-temperature relationships on rate of egg production over a nine-month reproductive period Strain
OA NM AIC OB WYO
1st to 5th months
6th to 9th months
1st to 9th months
(% hen-day (% hen-day (% hen-day eggs) eggs) eggs) 5.8* 3.3 4.7 0.5 10.5 4.9 2.3 9.9 5.7 11.8 7.1 9.4 13.8 10.2 12.2
* Data represent the average rate at which egg production in 65°F. environment exceeded that in 70-100°F. environment.
ler than those produced in the 6S°F. or "uncontrolled" rooms (Table 3). The average difference between weights of eggs produced in 65°F. and 70-100°F. environments was 4.2 ± .33 (SE) grams. In other words, eggs produced by birds in the 65°F. room were about 8% heavier. Although egg weight increased progressively through the periods regardless of environment, the differences between 6S°F. and 70-100°F. eggs were approximately the same for each period. The additional egg mass produced under 6S°F. temperature was 314 kg., which is equivalent to approximately 467 dozen eggs. Values reported in Table 4 demonstrated significant strain differences and a significant strain-temperature interaction for egg weight. The difference between weights of OB eggs produced in the 65 °F. environment and those from the 70-100°F. room TABLE 3.—Influence of ambient temperature on weight of eggs produced Temperature 65°F. 70-100°F. "uncontrolled"
Mean wt.-of (grams) 1 56.3" 52. l b 55.6*
1 Data with different superscripts are significantly different at the one percent level according to Duncan's multiple range test (1955).
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Egg Production. There were 1786, 1693, and 1429 dozens of eggs produced in 6S°F., "uncontrolled," and 70-100°F. environments respectively. Inasmuch as no statistical differences were found in rate of lay between 6S°F. and "uncontrolled" environments (Table 1), comparisons for strain-temperature relationships were made only between 6S°F. and 70-100°F. Rate of lay for the NM strain was similar under 6S°F. and 70-100°F. conditions during the first five months. This was followed by a sharp decline under the 70-100°F. environment during the 6th to 9 th month period. Birds from the Wyoming strain produced 13.8% fewer eggs in the 70100°F. room than in the 65°F. room during the first five months and 10.2% fewer during the 6th to 9th month period. The differences in rates of lay for AIC, OA, and OB strains in these two environments varied between these extremes with values for the AIC birds closely paralleling those of the NM strain (Table 2). There was a tendency for the strains to converge in relative rates of lay between temperatures as time progressed. However, values during the first five-month period, also averages for the 1-9 month period, indicated a particularly wide difference in rate of lay between temperatures with respect to NM and WYO strains. Egg Weight. Eggs produced under 70100°F. conditions were significantly smal-
1006
C. E. CLARK AND M. AMIN
TABLE 4.—Influence of ambient temperature on weight of eggs from different strains Ambient Temperatures Strain 6S°F.
70-100°F. ' 'uncontrolk
(grams) 57.0 56.9 59.4 53.9 54.3
(grams) 51.6 52.1 54.0 52.1 50.7
(grams) 55.9 55.4 59.6 54.1 53.0
Average
56.3
52.1
55.6
was significantly less than comparable differences between other strains. This temperature-affected difference was significantly smaller for the WYO eggs than for OA or AIC eggs. The difference between WYO and NM eggs, however, was not significant. Haugh Units. In general, ambient temperature of the chickens was found to have little affect on Haugh unit values of their eggs (Table 5). However, significant strain differences and strain-environmental interactions did occur. Eggs from WYO strain had significantly higher Haugh units under the 70-100°F. conditions than under the 6S°F. or "uncontrolled" conditions. The reverse was true with eggs from OA birds except the difference between 70100°F. and "uncontrolled" was not significant. The greatest Haugh unit differences between temperatures were found in OB eggs with 4-5 units less under "uncontrolled" temperature conditions than 65°F. or 70-100°F. and in WYO eggs with about 7 units less in "uncontrolled" than 70-100°F. A gradual decrement in Haugh" units by period was significant (P > .01) for all temperature conditions. Over the nine 28-day periods, the net decrement in Haugh units was 8.3, 6.7, and 10.2 in 65°F., 70-100°F., and "uncontrolled," respectively. Shell Thickness and Percentage Shell. Egg shells were about 6% thinner and per-
DISCUSSION Egg Production. All strains combined produced about 20 percent fewer eggs under 70-100°F. conditions than under 6S°F., during the 9-month period. On the basis of hen-day production it appeared that TABLE 5.—Influence of ambient temperature on Haugh unit values of eggs from different strains Ambient Temperatures Strain 65°F.
70-100°F. "uncontrolled"
OA NM AIC OB WYO
83.3 77.2 83.0 79.4 77.8
81.2 76.9 82.8 80.0 79.8
81.7 77.1 84.2 75.1 72.9
Average
80.1
80.1
78.2
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OA NM AIC OB WYO
centage shell 4% lower in the 70-100°F. than in the 6S°F. environment, and these values were about 8% and 6% lower, respectively, under 70-100°F. than under "uncontrolled" conditions. All comparative values were significantly lower under 70100°F. conditions. Although significant differences were observed between strains, no genetic-environmental relationships were evident for these factors. Mortality. The mortality rate under 70100°F. and "uncontrolled" temperatures was about double that under 65°F. conditions (Table 6). Strain differences were apparent in these relations. Oregon-A had the lowest mortality rate and seemed particularly tolerant to 70-100°F. WYO and NM birds had considerably higher mortality rates under the 70-100°F. temperatures, while mortality of AIC and OB birds was similar in the 70-100° F. and "uncontrolled" temperatures. Gross necropsies showed that disorders of the liver and of the reproductive organs were characteristic of birds adversely affected by 70100°F. temperature. A relationship between environment and the incidence of leucosis was also evident (Table 7).
1007
ENVIRONMENTAL ADAPTATION
TABLE 6.—Influence of ambient temperature on mortality of different strains of White Leghorn hens over a 9-month reproductive period Ambient Temperature Strain 65°F.
70-100°F. "uncontrolled"
OA NM AIC OB WYO
(No.) 0 10 3 2 10
(No.) 3 14 7 7 15
(No.) 9 11 9 8 10
Average
25
46
47
TABLE 7.—Physical disorders found on gross necropsy of chickens from different environments Diagnosis or observed
Peritonitis Leucosis Liver Reproductive organs Misc. or undetermined Total
Ambient Temperatures 65°F. (no. of birds) 4 1 4
70-100°F. "uncontrolled' (no. of birds) 2 3 13
(no. of birds) 9 6 5
Total
15 10 22
3
8
6
17
13
20
21
54
25
46
47
70-100°F. environments between the two strains that differed most as to the prevailing temperatures in their native environments (NM, WYO). The relatively moderate "uncontrolled" temperatures did not substantiate the genetic-environmental advantage that had been seen in the previous year when 30° to 55°F. temperature were recorded. These data are in general agreement with reports of others in that reproductive performance of chickens is adversely affected by prolonged exposure to ambient temperatures below 40°F. or above 90°F. According to Mueller (1961), chickens can adapt to short-term temperatures at these critical limits. Evidence for adaptation to short-term exposures to high temperature was also apparent when controlled diurnal temperature fluctuation followed a sine curve with peaks at 65°F. and 95°F. (Clark et al., 1963). The diurnal range of temperature may also be a factor in the adaptability of chickens to thermo-stress (Squibb, 1959). Egg Weight. Strain differences and strain-environmental interactions occurred with respect to egg weight. Relationships between the native climate of the strains and the environments imposed in this study, however, were not' as clearly correlated with one another as with egg production. Eggs of all strains were smaller when produced under 70-100°F. conditions than under 65°F., and the differences
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about 37 percent of this reduced rate of lay was attributed to higher mortality under the higher temperature conditions and about 63 percent of the reduction due to the continuous depressing effect of the higher temperatures on egg production. Data obtained from different birds of the same strains during the previous winter, when temperatures were 10-15 degrees cooler in the "uncontrolled" house; showed that such thermal stress (30-55°F.) was as critical for the commercial strain (AIC) as was the 70-100°F. temperatures. With this wider range of temperatures represented in the three environments that were studied the previous year, NM and WYO birds demonstrated marked strain-temperature relationships in the cool as in the warm environments. The relative egg production by NM birds was significantly higher under 70-100°F. conditions than under "uncontrolled," with the opposite being true for WYO birds. This suggests that NM birds were experiencing greater stress under the colder temperatures while the WYO strain was suffering under the warmer temperatures (Clark et al., 1963). The current study further substantiated genetic-environmental adaptations on the basis of rate of lay during the first five months of production and during the one to nine month period. These data were of particular interest since large differences existed in rate of lay between 65°F. and
1008
C. E. CLARK AND M. AMIN
as these factors influence the incidence of lymphomatosis. SUMMARY
Five strains of White Leghorns were studied to determine their adaptability to various normally encountered temperature conditions. The strains used had been developed at university experiment stations in Wyoming, with cool temperatures, New Mexico, with warm temperatures; and Oregon and Iowa, both with moderate temperatures. One Oregon strain and the Iowa birds were hybrids. Eggs were hatched at Logan, Utah, and pullets were reared together until 17 weeks of age. They were then housed in individual cages under three temperature conditions until sexual maturity plus nine months. Temperature regimes were: 65° ± 5°F. constant temperature; 70-100°F. diurnal fluctuating temperature with nine hours daily at 100°F.; and "uncontrolled" temperature. Genetic differences were evidenced in egg production, egg weight, Haugh units, shell thickness, percent shell, and in rate of mortality. Genetic-environmental relationships could be defined for all factors except shell thickness. Differences between environments were noted for all factors studied except Haugh units. Egg production was the only trait studied for which an obvious relationship existed between ambient temperature and native environment of strain. Fewer eggs were produced under 70-100°F. than under 65°F. conditions. The difference between these temperatures was smallest for the New Mexico birds and largest for the Wyoming birds, suggesting that rate of lay expresses the sensitivity of the adaptive mechanism of birds and that a bird's indigenous environment may influence this mechanism. ACKNOWLEDGMENT
Grateful appreciation is acknowledged for the helpful assistance of personnel from
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in egg weights produced under these two temperature conditions varied considerably among the strains. It may be coincidental that the difference in weights of eggs produced under these environments was significantly greater between the two hybrid strains (AIC and OA) than between the pure strains. It was of interest to note that the decreased egg weights obtained under 70-100°F. conditions were equivalent to 367 dozen eggs while the loss in numbers of eggs equaled 357 dozen. Haugh Units. Genetic and genetic-environmental relationships were evidenced in Haugh unit results. However, no clearly obvious relationship could be defined between the indigenous environment of the strains and the Haugh unit values of their eggs. Since the periodic decrement in Haugh unit values was of similar magnitude for all temperatures, increasing age appears to have a greater influence on Haugh unit decrement than does temperature. The variation in Haugh unit decrement between temperatures, however, may also suggest a slight temperature effect with a smaller decrement in the warmer temperature. Mortality. Strain differences in mortality reported here did not appear to be correlated with the chicken's native environment. Genetic variation in tolerance to heat stress was obvous, however. Certain physical disorders of birds submitted for necropsy could be correlated with the temperature they had experienced. The higher incidence of leucosis under natural environment conditions and of disorders of the liver and reproductive organs in the warm environment was of particular interest. Although these data are not conclusive, they suggest an important relationship of environment to the manifestation of various poultry diseases. Smith and Long (1959) have concluded that environment is of greater importance than heredity, at least
ENVIRONMENTAL ADAPTATION
the Veterinary Science Department and of Dr. Neeti R. Bohidar, Department of Applied Statistics. REFERENCES
Hutchinson, J. C. D., and A. H. Sykes, 1953. Physiological acclimatization of fowls to a hot, humid environment. J. Agr. Sci. 43 . 294-322. Kheireldin, M. A., and C. S. Shaffner, 1957. Familial differences in resistance to high environmental temperatures in chicks. Poultry Sci. 36: 1334-1339. Mueller, W. J., 1961. The effect of constant and fluctuating environmental temperatures in the biological performance of laying pullets. Poultry Sci. 40: 1562-1571. Smith, W. M., Jr., and G. H. Long, 1959. Effect of environment versus breeding on farm flock incidence of visceral lymphomatosis. J. Amer. Vet. Med. Assoc. 134: 373-376. Squibb, R. L., 1959. Relation of diurnal temperature and humidity ranges to egg production and feed efficiency of New Hampshire hens. J. Agr. Sci. 52: 217-222. Thornton, P. A., and R. E. Moreng, 1959. Further evidence in the value of ascorbic acid for maintenance of shell quality in warm environmental temperature. Poultry Sci. 38: 594-599.
Light Environment as a Factor in Growth and Feed Efficiency of Meat-Type Chickens W. L. BEANE, P. B. SIEGEL AND H. S. SIEGEL Virginia Polytechnic Institute, Blacksburg (Received for publication December 18, 1964)
N
UMEROUS investigations have demonstrated that meat-type chickens exposed to continuous light are heavier at broiler age than those given periods of light and darkness (e.g. Moore, 1957; Shutze et al., 1960; Krueger et aZ.,1962; Beane et al., 1962). Data obtained by the above investigators suggest that, although there are diurnal rhythms in feeding activity (Siegel and Guhl, 1956; Siegel et al., 1962), continuous illumination provides an advantage of increased feeding time for chickens with a rapid growth potential. This advantage was shown by Siegel and Wood (1964) who found that under continuous light chicks restricted in feeding
time weighed less than those fed ad libitum. If however, the sole function of light, in the maximum expression of juvenile growth, is through the facilitation of time for food consumption, then growth at several light intensities during a day should be comparable to that at a single intensity. Shutze et al. (1962), however, have shown that growth was different between flocks provided continuous artificial light and those given natural plus artificial illumination for continuous light. The experiments reported here were designed to compare the growth of meat-type chickens under continuous light at single
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Campos, A. C , F. H. Wilcox and C. S. Shaffner, 1960. The influence of fast and slow rises in ambient temperature on production traits and mortality of laying pullets. Poultry Sci. 39: 119-129. Clark, C. E., H. Nikoopour and C. I. Draper, 1963. Effects of temperature on egg production. Utah Farm and Home Sci. 24: 91, 105-106. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Hays, F. A., 1958. Laying house temperature and egg production. Poultry Sci. 37: 592-595. 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.
1009
uterus. The distention of the uterus did not permit the complete uptake of the semen. It, therefore, seemed likely that this would have an adverse effect on fertility. Evidence that this is not the case is presented in Table 2. The fertility levels of birds having a hard shell egg were comparable to those having already laid.
result of lack of technique rather than bacterial infection as previously suggested by Wentworth and Mellen (1963). The described technique resulted in no infection or mortality and did not depress egg production. Additional data regarding time of insemination, volume of semen per insemination, diluents, etc. are currently being collected. A later paper will provide information on refinements which will hopefully increase present fertility levels. REFERENCES Burrows, W. H., and J. P. Quinn, 1939. Artificial insemination of chickens and turkeys. U.S.D.A. Circular 525. Ogasawara, F. X., and R. Huang, 1963. A modified method of artificial insemination in the production of chicken-quail hybrids. Poultry Sci. 42: 1386-1392. Wentworth, B. C , and W. J. Mellen, 1963. Egg production and fertility following various methods of insemination of Japanese quail. J. Reprod. Fertil. 6: 215-220. Wilson, W. O., U. K. Abbott and H. Abplanalp, 1961. Evaluation of Coturnix (Japanese quail) as pilot animal for poultry. Poultry Sci. 40: 651-657.
The Adaptability of Chickens to Various Temperatures 1 C. E. CLARK AND M. AMIN 2 Poultry Department, Utah State University, Logan, Utah (Received for publication December 17, 1964)
C
HICKENS deviate from their potential in reproductive performance when challenged by environmental conditions. Prolonged exposure to temperatures above 90°F. (Mueller, 1961) or below 1
Approved as Utah Agricultural Experiment Station Journal Paper No. 443. 2 Present Address: Karadj College, University of Tehran, Tehran, Iran.
60°F. (Hays, 1958) results in a reduced egg yield. Eggs produced under high air temperature conditions have thinner than normal shells and as a result are particularly fragile (Thornton and Moreng, 1959). These relationships are economically significant to the egg industry since meteorological variations constitute hazards in many poultry producing areas of the world.
Downloaded from http://ps.oxfordjournals.org/ at Library of Medical Center of Fudan University on May 9, 2015
DISCUSSION Although it is necessary that attempts be made to improve the fertility levels reported herein, it appears that this method provides a practical technique which will yield good results. Equal, if not superior results, to the laborious technique reported by Wentworth and Mellen (1963) were obtained. Fertility in 83 percent of birds inseminated compares favorably with the 77.5 percent figure reported by these workers. It is difficult to compare the two methods regarding fertility of total eggs since this value was not reported by Wentworth and Mellen. This study indicates that the inability to obtain satisfactory fertility levels from artificial insemination in Coturnix is the
1003
1004
C. E. CLARK AND M. AMIN
MATERIALS AND METHODS
Hatching eggs from four White Leghorn-type strains were obtained from university experiment stations in Wyoming (WYO), New Mexico (NM), and Oregon; (OA) indicates Oregon hybrid, and (OB) Oregon pure strain. These strains had been developed over a period of several years at their respective locations and thus each had been subject to unique conditions of altitude and temperature. Conditions at the various stations include: Wyoming at a 7250-foot elevation with a relatively cool temperature; New Mexico at about a 3900foot elevation with a warm temperature; Oregon at about a 240 foot elevation with a moderate temperature. Mean temperature differences are about 25°F. between the Wyoming and New Mexico stations. Eggs from a fifth strain were from commercial hybrid stock (AIC). Chicks from all strains were hatched together at Logan, Utah, intermingled until 17 weeks of age, and then transferred to individual cages located inside three rooms. The temperature regimes in two rooms of a windowless house consisted of 70-100° ± 3°F., and 65° ± 5°F. constant, respectively. The 70-100°F. regime fluctuated diurnally on the basis of a controlled program which specified 100°F. from 9:00
A.M. to 6:00 P.M. 70°F. from 12:00 midto 3:00 A.M. Six hours were allowed for the transition from 100°F. to 70°F. and vice versa. The third environment utilized a conventional-type poultry building wherein no set temperature was maintained and only factors contributed by animal heat, structural insulation, and mechanical ventilation were operative. Monthly mean temperatures, derived from averages of daily minimums and maximums recorded inside the "uncontrolled" house were: 55°F., November; 50°F., December; 45°F., January; 47°F., February; 54°F., March; 58°F., April; 72°F., May; 73°F., June. Fourteen hours of light were provided in the controlled environments. Daylight simply was not excluded in the "uncontrolled" house. One hundred-eighty pullets were arranged systematically in each of the three environments. Five birds constituted a unit and eight units were established for each of the strains: WYO, NM, and AIC. Six units were established for OA and six for OB. An all-mash laying ration was fed ad libitum with no nutritional variables, and continuously running water was provided. Observations were made over nine-2 8-day periods on eggs produced, egg weights, Haugh units, egg shell thicknesses, and percent shell values. A necropsy was performed on all birds that died. Egg shell and interior quality determinations were made from the mean value of two randomly selected eggs from each experimental unit. Egg shell thickness was determined on dried shells with membranes removed. The average of four thickness measurements (two sides and two ends) was recorded as shell thickness. The data were processed through techniques of analysis of variance and Duncan's new multiple range test (1955).
Downloaded from http://ps.oxfordjournals.org/ at Library of Medical Center of Fudan University on May 9, 2015
There is evidence that genetic differences affect the sensitivity and adaptability of chickens to high environmental temperatures. This appears to be true between breeds (Huston et al., 19S7; Campos et al., 1960) and between families (Kheireldin and Shaffner, 1957). Individuals in a family have also demonstrated differences in acclimatization to hot humid environments (Hutchinson and Sykes, 1953). Genetic-environmental relationships with respect to adaptation of strains to different climates are reported here.
1005
ENVIRONMENTAL ADAPTATION RESULTS
TABLE 1.—Influence of ambient temperature on number of eggs produced Temperature
Mean % Hen-day eggs1
65°F. 70-100°F. "uncontrolled"
52.7" 45.5 b 52.1-
1 Data with different superscripts are significantly different at the one percent level according to Duncan's multiple range test (1955).
TABLE 2.—Strain-temperature relationships on rate of egg production over a nine-month reproductive period Strain
OA NM AIC OB WYO
1st to 5th months
6th to 9th months
1st to 9th months
(% hen-day (% hen-day (% hen-day eggs) eggs) eggs) 5.8* 3.3 4.7 0.5 10.5 4.9 2.3 9.9 5.7 11.8 7.1 9.4 13.8 10.2 12.2
* Data represent the average rate at which egg production in 65°F. environment exceeded that in 70-100°F. environment.
ler than those produced in the 6S°F. or "uncontrolled" rooms (Table 3). The average difference between weights of eggs produced in 65°F. and 70-100°F. environments was 4.2 ± .33 (SE) grams. In other words, eggs produced by birds in the 65°F. room were about 8% heavier. Although egg weight increased progressively through the periods regardless of environment, the differences between 6S°F. and 70-100°F. eggs were approximately the same for each period. The additional egg mass produced under 6S°F. temperature was 314 kg., which is equivalent to approximately 467 dozen eggs. Values reported in Table 4 demonstrated significant strain differences and a significant strain-temperature interaction for egg weight. The difference between weights of OB eggs produced in the 65 °F. environment and those from the 70-100°F. room TABLE 3.—Influence of ambient temperature on weight of eggs produced Temperature 65°F. 70-100°F. "uncontrolled"
Mean wt.-of (grams) 1 56.3" 52. l b 55.6*
1 Data with different superscripts are significantly different at the one percent level according to Duncan's multiple range test (1955).
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Egg Production. There were 1786, 1693, and 1429 dozens of eggs produced in 6S°F., "uncontrolled," and 70-100°F. environments respectively. Inasmuch as no statistical differences were found in rate of lay between 6S°F. and "uncontrolled" environments (Table 1), comparisons for strain-temperature relationships were made only between 6S°F. and 70-100°F. Rate of lay for the NM strain was similar under 6S°F. and 70-100°F. conditions during the first five months. This was followed by a sharp decline under the 70-100°F. environment during the 6th to 9 th month period. Birds from the Wyoming strain produced 13.8% fewer eggs in the 70100°F. room than in the 65°F. room during the first five months and 10.2% fewer during the 6th to 9th month period. The differences in rates of lay for AIC, OA, and OB strains in these two environments varied between these extremes with values for the AIC birds closely paralleling those of the NM strain (Table 2). There was a tendency for the strains to converge in relative rates of lay between temperatures as time progressed. However, values during the first five-month period, also averages for the 1-9 month period, indicated a particularly wide difference in rate of lay between temperatures with respect to NM and WYO strains. Egg Weight. Eggs produced under 70100°F. conditions were significantly smal-
1006
C. E. CLARK AND M. AMIN
TABLE 4.—Influence of ambient temperature on weight of eggs from different strains Ambient Temperatures Strain 6S°F.
70-100°F. ' 'uncontrolk
(grams) 57.0 56.9 59.4 53.9 54.3
(grams) 51.6 52.1 54.0 52.1 50.7
(grams) 55.9 55.4 59.6 54.1 53.0
Average
56.3
52.1
55.6
was significantly less than comparable differences between other strains. This temperature-affected difference was significantly smaller for the WYO eggs than for OA or AIC eggs. The difference between WYO and NM eggs, however, was not significant. Haugh Units. In general, ambient temperature of the chickens was found to have little affect on Haugh unit values of their eggs (Table 5). However, significant strain differences and strain-environmental interactions did occur. Eggs from WYO strain had significantly higher Haugh units under the 70-100°F. conditions than under the 6S°F. or "uncontrolled" conditions. The reverse was true with eggs from OA birds except the difference between 70100°F. and "uncontrolled" was not significant. The greatest Haugh unit differences between temperatures were found in OB eggs with 4-5 units less under "uncontrolled" temperature conditions than 65°F. or 70-100°F. and in WYO eggs with about 7 units less in "uncontrolled" than 70-100°F. A gradual decrement in Haugh" units by period was significant (P > .01) for all temperature conditions. Over the nine 28-day periods, the net decrement in Haugh units was 8.3, 6.7, and 10.2 in 65°F., 70-100°F., and "uncontrolled," respectively. Shell Thickness and Percentage Shell. Egg shells were about 6% thinner and per-
DISCUSSION Egg Production. All strains combined produced about 20 percent fewer eggs under 70-100°F. conditions than under 6S°F., during the 9-month period. On the basis of hen-day production it appeared that TABLE 5.—Influence of ambient temperature on Haugh unit values of eggs from different strains Ambient Temperatures Strain 65°F.
70-100°F. "uncontrolled"
OA NM AIC OB WYO
83.3 77.2 83.0 79.4 77.8
81.2 76.9 82.8 80.0 79.8
81.7 77.1 84.2 75.1 72.9
Average
80.1
80.1
78.2
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OA NM AIC OB WYO
centage shell 4% lower in the 70-100°F. than in the 6S°F. environment, and these values were about 8% and 6% lower, respectively, under 70-100°F. than under "uncontrolled" conditions. All comparative values were significantly lower under 70100°F. conditions. Although significant differences were observed between strains, no genetic-environmental relationships were evident for these factors. Mortality. The mortality rate under 70100°F. and "uncontrolled" temperatures was about double that under 65°F. conditions (Table 6). Strain differences were apparent in these relations. Oregon-A had the lowest mortality rate and seemed particularly tolerant to 70-100°F. WYO and NM birds had considerably higher mortality rates under the 70-100°F. temperatures, while mortality of AIC and OB birds was similar in the 70-100° F. and "uncontrolled" temperatures. Gross necropsies showed that disorders of the liver and of the reproductive organs were characteristic of birds adversely affected by 70100°F. temperature. A relationship between environment and the incidence of leucosis was also evident (Table 7).
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ENVIRONMENTAL ADAPTATION
TABLE 6.—Influence of ambient temperature on mortality of different strains of White Leghorn hens over a 9-month reproductive period Ambient Temperature Strain 65°F.
70-100°F. "uncontrolled"
OA NM AIC OB WYO
(No.) 0 10 3 2 10
(No.) 3 14 7 7 15
(No.) 9 11 9 8 10
Average
25
46
47
TABLE 7.—Physical disorders found on gross necropsy of chickens from different environments Diagnosis or observed
Peritonitis Leucosis Liver Reproductive organs Misc. or undetermined Total
Ambient Temperatures 65°F. (no. of birds) 4 1 4
70-100°F. "uncontrolled' (no. of birds) 2 3 13
(no. of birds) 9 6 5
Total
15 10 22
3
8
6
17
13
20
21
54
25
46
47
70-100°F. environments between the two strains that differed most as to the prevailing temperatures in their native environments (NM, WYO). The relatively moderate "uncontrolled" temperatures did not substantiate the genetic-environmental advantage that had been seen in the previous year when 30° to 55°F. temperature were recorded. These data are in general agreement with reports of others in that reproductive performance of chickens is adversely affected by prolonged exposure to ambient temperatures below 40°F. or above 90°F. According to Mueller (1961), chickens can adapt to short-term temperatures at these critical limits. Evidence for adaptation to short-term exposures to high temperature was also apparent when controlled diurnal temperature fluctuation followed a sine curve with peaks at 65°F. and 95°F. (Clark et al., 1963). The diurnal range of temperature may also be a factor in the adaptability of chickens to thermo-stress (Squibb, 1959). Egg Weight. Strain differences and strain-environmental interactions occurred with respect to egg weight. Relationships between the native climate of the strains and the environments imposed in this study, however, were not' as clearly correlated with one another as with egg production. Eggs of all strains were smaller when produced under 70-100°F. conditions than under 65°F., and the differences
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about 37 percent of this reduced rate of lay was attributed to higher mortality under the higher temperature conditions and about 63 percent of the reduction due to the continuous depressing effect of the higher temperatures on egg production. Data obtained from different birds of the same strains during the previous winter, when temperatures were 10-15 degrees cooler in the "uncontrolled" house; showed that such thermal stress (30-55°F.) was as critical for the commercial strain (AIC) as was the 70-100°F. temperatures. With this wider range of temperatures represented in the three environments that were studied the previous year, NM and WYO birds demonstrated marked strain-temperature relationships in the cool as in the warm environments. The relative egg production by NM birds was significantly higher under 70-100°F. conditions than under "uncontrolled," with the opposite being true for WYO birds. This suggests that NM birds were experiencing greater stress under the colder temperatures while the WYO strain was suffering under the warmer temperatures (Clark et al., 1963). The current study further substantiated genetic-environmental adaptations on the basis of rate of lay during the first five months of production and during the one to nine month period. These data were of particular interest since large differences existed in rate of lay between 65°F. and
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C. E. CLARK AND M. AMIN
as these factors influence the incidence of lymphomatosis. SUMMARY
Five strains of White Leghorns were studied to determine their adaptability to various normally encountered temperature conditions. The strains used had been developed at university experiment stations in Wyoming, with cool temperatures, New Mexico, with warm temperatures; and Oregon and Iowa, both with moderate temperatures. One Oregon strain and the Iowa birds were hybrids. Eggs were hatched at Logan, Utah, and pullets were reared together until 17 weeks of age. They were then housed in individual cages under three temperature conditions until sexual maturity plus nine months. Temperature regimes were: 65° ± 5°F. constant temperature; 70-100°F. diurnal fluctuating temperature with nine hours daily at 100°F.; and "uncontrolled" temperature. Genetic differences were evidenced in egg production, egg weight, Haugh units, shell thickness, percent shell, and in rate of mortality. Genetic-environmental relationships could be defined for all factors except shell thickness. Differences between environments were noted for all factors studied except Haugh units. Egg production was the only trait studied for which an obvious relationship existed between ambient temperature and native environment of strain. Fewer eggs were produced under 70-100°F. than under 65°F. conditions. The difference between these temperatures was smallest for the New Mexico birds and largest for the Wyoming birds, suggesting that rate of lay expresses the sensitivity of the adaptive mechanism of birds and that a bird's indigenous environment may influence this mechanism. ACKNOWLEDGMENT
Grateful appreciation is acknowledged for the helpful assistance of personnel from
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in egg weights produced under these two temperature conditions varied considerably among the strains. It may be coincidental that the difference in weights of eggs produced under these environments was significantly greater between the two hybrid strains (AIC and OA) than between the pure strains. It was of interest to note that the decreased egg weights obtained under 70-100°F. conditions were equivalent to 367 dozen eggs while the loss in numbers of eggs equaled 357 dozen. Haugh Units. Genetic and genetic-environmental relationships were evidenced in Haugh unit results. However, no clearly obvious relationship could be defined between the indigenous environment of the strains and the Haugh unit values of their eggs. Since the periodic decrement in Haugh unit values was of similar magnitude for all temperatures, increasing age appears to have a greater influence on Haugh unit decrement than does temperature. The variation in Haugh unit decrement between temperatures, however, may also suggest a slight temperature effect with a smaller decrement in the warmer temperature. Mortality. Strain differences in mortality reported here did not appear to be correlated with the chicken's native environment. Genetic variation in tolerance to heat stress was obvous, however. Certain physical disorders of birds submitted for necropsy could be correlated with the temperature they had experienced. The higher incidence of leucosis under natural environment conditions and of disorders of the liver and reproductive organs in the warm environment was of particular interest. Although these data are not conclusive, they suggest an important relationship of environment to the manifestation of various poultry diseases. Smith and Long (1959) have concluded that environment is of greater importance than heredity, at least
ENVIRONMENTAL ADAPTATION
the Veterinary Science Department and of Dr. Neeti R. Bohidar, Department of Applied Statistics. REFERENCES
Hutchinson, J. C. D., and A. H. Sykes, 1953. Physiological acclimatization of fowls to a hot, humid environment. J. Agr. Sci. 43 . 294-322. Kheireldin, M. A., and C. S. Shaffner, 1957. Familial differences in resistance to high environmental temperatures in chicks. Poultry Sci. 36: 1334-1339. Mueller, W. J., 1961. The effect of constant and fluctuating environmental temperatures in the biological performance of laying pullets. Poultry Sci. 40: 1562-1571. Smith, W. M., Jr., and G. H. Long, 1959. Effect of environment versus breeding on farm flock incidence of visceral lymphomatosis. J. Amer. Vet. Med. Assoc. 134: 373-376. Squibb, R. L., 1959. Relation of diurnal temperature and humidity ranges to egg production and feed efficiency of New Hampshire hens. J. Agr. Sci. 52: 217-222. Thornton, P. A., and R. E. Moreng, 1959. Further evidence in the value of ascorbic acid for maintenance of shell quality in warm environmental temperature. Poultry Sci. 38: 594-599.
Light Environment as a Factor in Growth and Feed Efficiency of Meat-Type Chickens W. L. BEANE, P. B. SIEGEL AND H. S. SIEGEL Virginia Polytechnic Institute, Blacksburg (Received for publication December 18, 1964)
N
UMEROUS investigations have demonstrated that meat-type chickens exposed to continuous light are heavier at broiler age than those given periods of light and darkness (e.g. Moore, 1957; Shutze et al., 1960; Krueger et aZ.,1962; Beane et al., 1962). Data obtained by the above investigators suggest that, although there are diurnal rhythms in feeding activity (Siegel and Guhl, 1956; Siegel et al., 1962), continuous illumination provides an advantage of increased feeding time for chickens with a rapid growth potential. This advantage was shown by Siegel and Wood (1964) who found that under continuous light chicks restricted in feeding
time weighed less than those fed ad libitum. If however, the sole function of light, in the maximum expression of juvenile growth, is through the facilitation of time for food consumption, then growth at several light intensities during a day should be comparable to that at a single intensity. Shutze et al. (1962), however, have shown that growth was different between flocks provided continuous artificial light and those given natural plus artificial illumination for continuous light. The experiments reported here were designed to compare the growth of meat-type chickens under continuous light at single
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Campos, A. C , F. H. Wilcox and C. S. Shaffner, 1960. The influence of fast and slow rises in ambient temperature on production traits and mortality of laying pullets. Poultry Sci. 39: 119-129. Clark, C. E., H. Nikoopour and C. I. Draper, 1963. Effects of temperature on egg production. Utah Farm and Home Sci. 24: 91, 105-106. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Hays, F. A., 1958. Laying house temperature and egg production. Poultry Sci. 37: 592-595. 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.
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