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Population Size and Density as Related to Laying House Performance1,2
896
R . H . ROBERSON AND P . J . SCHAIBLE
O'Dell, B. L., P. M. Newberne and J. E. Savage, 1958. Significance of dietary zinc for the growing chicken. J. Nutrition, 65: 503-523. Roberson, R. H., and P. J. Schaible, 1958. The zinc requirement of the chick. Poultry Sci. 37 :
1321-1323. Snedecor, G. W., 1956. Statistical Methods. 5th edition. The Iowa State College Press, Ames, Iowa.
Population Size and Density as Related to Laying House Performance1-2 THOMAS W. FOX 3 AND JOE T. CLAYTON4 University of Massachusetts, Amherst, Massachusetts (Received for publication October 13, 1959)
M
ANY poultry production management recommendations are not based on research results. One such recommendation, floor space per bird, is surprisingly void of supporting research data. The floor space requirements suggested by voluminous extension and commercial management publications are based on size of bird and approximate concentrations of birds that have been shown to be compatible with dry litter under a range of housing designs and quality. Advances in the technology of poultry housing materials, equipment, and ventilation systems have made substantial progress in controlling the litter moisture problem. Bressler (1956) has reported the results of a housing demonstration where satisfactory litter conditions were maintained at bird densities of one square foot floor space per bird. 1
Contribution No. 1220 from the Massachusetts Agricultural Experiment Station, Amherst. 2 This study was conducted as part of a Northeast Regional Project (N.E.8); a cooperative study involving agricultural experiment stations in the Northeastern Region and supported in part by regional funds of the United States Department of Agriculture. 3 Department of Poultry Science. 'Department of Agricultural Engineering.
That crowding may provide a potent stress factor is nicely demonstrated by the work of Christian (1957) with mice. Siegel (1958) has studied the effect of floor space allowance on growth, livability and adrenal function in broilers and more recently, Siegel (1959) has reported a series of experiments concerned with floor space allowance and egg production. It was found that egg production was lower in S. C. White Leghorn pullets housed at 1.33 square feet per bird as compared to 4.00 square feet per bird. This lower production was due to a lower rate of lay of birds in production and not to the number of birds laying. The importance of flock size is a matter for conjecture. Field observations and management practices largely determine general size recommendations. Studies by Banks and Allee (1957) and Guhl (1953) have reported the effects of flock size on agonistic behavior of chickens. Pecks, threats, and avoids,—three aspects of agonistic behavior, have been demonstrated to be related to flock size. The purpose of the studies reported herein was to determine the effects of floor space and flock size on laying house performance under winter conditions.
SPACE AND LAYING PERFORMANCE
EXPERIMENTAL PROCEDURE
These studies were conducted in a 12foot by 100-foot house which was divided into nine pens. These nine pens housed three flocks of each of the three nominal sizes of 30, 60, and 100 birds at 1, 2, and 3 square feet per bird and constituted a 3 X 3 factorial experiment. The house was partially insulated. (Heat transmission coefficients Were approximately: wall, U = 0.29 Btu/(hf. °F. ft. 2 ); ceiling, U = 0.099 Btu/(hr. °F. ft. 2 ). It was mechanically ventilated by a system having a maximum capacity of about four cubic feet per minute per bird. The various pens were equipped with elevated slat floors. Management practices were the same throughout the house. Temperature and relative humidity data collected by means of hygro-thermographs near the center of each pen and at a height of 18 inches above the floor showed that these environmental factors varied about the same from pen to pen. The thermostats controlling the ventilating fans were set for a 38°F. minimum. Absolute minimum temperatures within the pens were usually only about two degrees below the thermostatic setting of the fans. However, on a few occasions, during extended periods of extremely cold weather, the inside temperature dropped low enough to cause freezing of the pan type waterers. Mean radiant temperature, as indicated by a thermocople suspended at the center of a 6 inch black globe located three feet above the floor at the center of the pen, varied approximately two degrees, above or below air temperature, but the variation was essentially the same from pen to pen. The equipment used in this house consisted of tube-type feeders, automatic waterers, rollaway nests and no roosts. Feeder space provided was one fifty pound tube feeder per 30 birds or approximately 2" of
897
feeder space per bird, and each pen had one pan-type automatic waterer. A commercial high energy laying mash, containing a productive energy of approximately 900 Calories per pound, was fed throughout these experiments. The stock used was a sex-linked crossbred produced by mating R.I. Red males with B. R. females. The 1956-57 birds were produced from University stock whereas 1957-58 and 1958-59 studies utilized a commercial sex-linked cross. The birds were hatched, brooded and range-reared at the University farm and were housed at approximately 5 months of age. All birds were debeaked prior to housing. Egg production, mortality and feed consumption data were obtained for a 28-week period each year from November 1 through June 1. Body weights were obtained at housing and during the month of March. During the last two years of the experiment egg quality studies were also conducted. EXPERIMENTAL RESULTS
A summary of the three years' results for hen-day egg production, mortality and feed required per dozen eggs are presented in Table 1. An analysis of variance of these data is shown in Table 2. As would be expected, there were significant yearly differences in all the characteristics studied. The hen-day egg production for the 28week periods was significantly different for floor space allocation or the density at which the birds were housed. The means for one, two, and three square feet per bird as shown in Table 1 are 51.1%, 56.1% and 55.1% respectively. The major production difference was observed between the one square foot and the greater floor space allowances. The effect of flock size on hen-day egg production approached significance; and although the F-ratio was less than required for the .05 probability level of significance,
T. W. Fox
898
AND J. T. CLAYTON
TABLE 1.—Three year summary of egg production, mortality and feed efficiency 1 ftVbird Flock size
Hen-day prod.
%
Mort.
%
2 ft.Vbird Hen-day Lbs. feed/doz. prod. eggs
Mort.
%
%
Floor space allotment 3 ft.Vbird
Hen-day Lbs. feed/doz. prod. eggs
%
Mort.
%
Ave: (flock size) Hen-day Lbs. feed/doz. prod. eggs
%
30 60 100
53.5 50.8 49.0
16.9 15.6 17.7
8.50 7.37 7.29
58.9 52.9 56.6
13.6 20.1 15.4
7.10 7.15 6.78
58.0 55.3 52.1
19.0 13.4 17.4
7.56 7.23 7.41
56.8 53.0 52.5
Ave. (floor space)
51.1
16.7
7.72
56.1
16.5
7.01
55.1
16.1
7.40
-
it is of interest that the 30-bird flocks had a higher percent production than the 60- or 100-bird flocks at all three bird densities. Again, the greatest production difference was provided by a comparison of the 30bird pens versus the two larger sizes. There was no evidence of a flock size X flock density interaction. The feed efficiency data indicated only significant differences among years. However, these data, shown in Table 1, agree with the production differences among flock densities with the better production groups usually showing the better efficiency. A reversal of this foregoing trend is shown in the flock size data. Here the smaller pen size, thirty birds, has the poorer efficiency in spite of better production. This relationship exists within all three flock densities. The mortality results are presented in Table 1 and it can be seen that no consistTABLE 2.—Analysis of variance of egg production and feed efficiency
Source
Dif.
Mean
Mean
square,
square, feed/doz eggs
egg
prod.
Total Floor space Flock size Years Floor space X flock size Floor spaceXyears Years X size Floor space X flock size Xyears
*P<.05. **P<.01.
26 2 2 2 4 4 4
%
Lbs. feed/doz. eggs
16.5 16.4 17.0
7.71 7.25 7.16
Mort.
-
ent mortality trends were evident in the three-year summary. All birds dying were subjected to post-mortem examination, and with the exception of the 1956-57 test year, when a rather severe chronic respiratory infection was evident, no serious disease problem existed. The major cause of mortality was the leucosis complex. Body weights were obtained during late February in 1957-58 and during March in the 1958-59 test year. The body weights for the 1957-58 year were significantly different for the flock-density treatments (P < .05) with the greater density pens having the lower weights. However, this relationship of body weight to pen-density was not evident in the 1958-59 data. Also, egg quality observations were made in both the 1957-58 and 1958-59 years. One such examination, Feb., 1958, indicated a significantly greater blood spot incidence at the high bird densities but subsequent studies later in the year and again during the 1958-59 season failed to substantiate this. There was no significant association of blood spots, meat spots, albumen height, or egg size with flock size or flock density. DISCUSSION
63.1* 49.3 177.9** 10.1 16.4
1.13 .81
7.48* .38
1.28
9.7
.13
14.1
.29
The interpretation of the results of pilot management studies such as reported herein requires caution. The results of any experiment with biological material are only applicable to the population studied and to the particular set of environmental conditions under which the experiment was
SPACE AND LAYING PERFORMANCE
conducted. Extrapolation of these results to all strains of chicken under all types and sizes of commercial operations would not be justified. The results of these studies have established that under the conditions of these experiments, increased numbers of birds per unit of floor space will cause a decrease in hen-day egg production. This reduction was not associated with any obvious environmental effects as all birds were housed on elevated slat floors to eliminate the litter problem. Feed, water, and nesting space were comparable among treatment groups. The air temperature and relative humidity were also quite uniform among pens due to the incomplete partitions separating the pens and the type of ventilation system employed. No attempt will be made to evaluate the economics of housing additional birds per unit of floor space. However, there was no substantial depression between two and three square foot allowances, with the significant reduction occurring between the one and two square foot per bird treatments. These results suggest the production response is not linearly relately to floor space allocation. This non-linearity of response causes further complication in extrapolation to the variety of housing and environmental conditions seen in commercial operations. These experiments provide some evidence that flock size may influence productive performance. The 30-bird pens were superior to the 60- and 100-bird pens at all three floor space densities. Again, extrapolation to commercial conditions is difficult as the largest pen size in these experiments would be considered very small in commercial flocks. However, the pen
899
size factor would be important in certain testing procedures such as Standard and Random Sample Testing programs. SUMMARY
1. Under the conditions of these experiments including slat floor and mechanical ventilation a floor space allowance of one square foot per bird significantly depressed hen-day egg production when compared to the two and three square foot per bird treatments. 2. Production differences between flock sizes (30, 60, and 100 birds) were not statistically significant, but approached significance, and the 30-bird flocks consistently had the best production regardless of floor space allocation. 3. No significant treatment effects on mortality were observed during the three year experiment. 4. No interaction of flock density with flock size was evident in these studies. REFERENCES Banks, E. M., and W. C. Allee, 1957. Some relations between flock size and agonistic behavior in domestic hens. Phys. Zool. 30: 255-268. Bressler, G. O., and H. V. Walton, 1956. The Penn State solar house. Pennsylvania Agr. Exp. Sta. Progress Report No. 162. Christian, J. J., and C. D. Lemunyan, 19S7. Adverse effects of crowding on reproduction and lactation of mice and two generations of their progeny. Naval Medical Research Institute Research Report, IS: 925-936. Guhl, A. M., 1953. Social behavior of the domestic fowl. Kansas Agr. Exp. Sta. Tech. Bui. 73: 1^8. Siegel, H. S., 19S8. Effects of increased population density on the adrenals of cockerels. Poultry Sci. 37: 1242. Siegel, H. S., 19S9. Egg production characteristics and adrenal function in White Leghorns confined at different floor space levels. Poultry Sci. 38:893-898.
OCTOBER 4-6. NEPPCO EXPOSITION AND CONVENTION, ONONDAGA WAR MEMORIAL AUDITORIUM, SYRACUSE, N.Y.
R . H . ROBERSON AND P . J . SCHAIBLE
O'Dell, B. L., P. M. Newberne and J. E. Savage, 1958. Significance of dietary zinc for the growing chicken. J. Nutrition, 65: 503-523. Roberson, R. H., and P. J. Schaible, 1958. The zinc requirement of the chick. Poultry Sci. 37 :
1321-1323. Snedecor, G. W., 1956. Statistical Methods. 5th edition. The Iowa State College Press, Ames, Iowa.
Population Size and Density as Related to Laying House Performance1-2 THOMAS W. FOX 3 AND JOE T. CLAYTON4 University of Massachusetts, Amherst, Massachusetts (Received for publication October 13, 1959)
M
ANY poultry production management recommendations are not based on research results. One such recommendation, floor space per bird, is surprisingly void of supporting research data. The floor space requirements suggested by voluminous extension and commercial management publications are based on size of bird and approximate concentrations of birds that have been shown to be compatible with dry litter under a range of housing designs and quality. Advances in the technology of poultry housing materials, equipment, and ventilation systems have made substantial progress in controlling the litter moisture problem. Bressler (1956) has reported the results of a housing demonstration where satisfactory litter conditions were maintained at bird densities of one square foot floor space per bird. 1
Contribution No. 1220 from the Massachusetts Agricultural Experiment Station, Amherst. 2 This study was conducted as part of a Northeast Regional Project (N.E.8); a cooperative study involving agricultural experiment stations in the Northeastern Region and supported in part by regional funds of the United States Department of Agriculture. 3 Department of Poultry Science. 'Department of Agricultural Engineering.
That crowding may provide a potent stress factor is nicely demonstrated by the work of Christian (1957) with mice. Siegel (1958) has studied the effect of floor space allowance on growth, livability and adrenal function in broilers and more recently, Siegel (1959) has reported a series of experiments concerned with floor space allowance and egg production. It was found that egg production was lower in S. C. White Leghorn pullets housed at 1.33 square feet per bird as compared to 4.00 square feet per bird. This lower production was due to a lower rate of lay of birds in production and not to the number of birds laying. The importance of flock size is a matter for conjecture. Field observations and management practices largely determine general size recommendations. Studies by Banks and Allee (1957) and Guhl (1953) have reported the effects of flock size on agonistic behavior of chickens. Pecks, threats, and avoids,—three aspects of agonistic behavior, have been demonstrated to be related to flock size. The purpose of the studies reported herein was to determine the effects of floor space and flock size on laying house performance under winter conditions.
SPACE AND LAYING PERFORMANCE
EXPERIMENTAL PROCEDURE
These studies were conducted in a 12foot by 100-foot house which was divided into nine pens. These nine pens housed three flocks of each of the three nominal sizes of 30, 60, and 100 birds at 1, 2, and 3 square feet per bird and constituted a 3 X 3 factorial experiment. The house was partially insulated. (Heat transmission coefficients Were approximately: wall, U = 0.29 Btu/(hf. °F. ft. 2 ); ceiling, U = 0.099 Btu/(hr. °F. ft. 2 ). It was mechanically ventilated by a system having a maximum capacity of about four cubic feet per minute per bird. The various pens were equipped with elevated slat floors. Management practices were the same throughout the house. Temperature and relative humidity data collected by means of hygro-thermographs near the center of each pen and at a height of 18 inches above the floor showed that these environmental factors varied about the same from pen to pen. The thermostats controlling the ventilating fans were set for a 38°F. minimum. Absolute minimum temperatures within the pens were usually only about two degrees below the thermostatic setting of the fans. However, on a few occasions, during extended periods of extremely cold weather, the inside temperature dropped low enough to cause freezing of the pan type waterers. Mean radiant temperature, as indicated by a thermocople suspended at the center of a 6 inch black globe located three feet above the floor at the center of the pen, varied approximately two degrees, above or below air temperature, but the variation was essentially the same from pen to pen. The equipment used in this house consisted of tube-type feeders, automatic waterers, rollaway nests and no roosts. Feeder space provided was one fifty pound tube feeder per 30 birds or approximately 2" of
897
feeder space per bird, and each pen had one pan-type automatic waterer. A commercial high energy laying mash, containing a productive energy of approximately 900 Calories per pound, was fed throughout these experiments. The stock used was a sex-linked crossbred produced by mating R.I. Red males with B. R. females. The 1956-57 birds were produced from University stock whereas 1957-58 and 1958-59 studies utilized a commercial sex-linked cross. The birds were hatched, brooded and range-reared at the University farm and were housed at approximately 5 months of age. All birds were debeaked prior to housing. Egg production, mortality and feed consumption data were obtained for a 28-week period each year from November 1 through June 1. Body weights were obtained at housing and during the month of March. During the last two years of the experiment egg quality studies were also conducted. EXPERIMENTAL RESULTS
A summary of the three years' results for hen-day egg production, mortality and feed required per dozen eggs are presented in Table 1. An analysis of variance of these data is shown in Table 2. As would be expected, there were significant yearly differences in all the characteristics studied. The hen-day egg production for the 28week periods was significantly different for floor space allocation or the density at which the birds were housed. The means for one, two, and three square feet per bird as shown in Table 1 are 51.1%, 56.1% and 55.1% respectively. The major production difference was observed between the one square foot and the greater floor space allowances. The effect of flock size on hen-day egg production approached significance; and although the F-ratio was less than required for the .05 probability level of significance,
T. W. Fox
898
AND J. T. CLAYTON
TABLE 1.—Three year summary of egg production, mortality and feed efficiency 1 ftVbird Flock size
Hen-day prod.
%
Mort.
%
2 ft.Vbird Hen-day Lbs. feed/doz. prod. eggs
Mort.
%
%
Floor space allotment 3 ft.Vbird
Hen-day Lbs. feed/doz. prod. eggs
%
Mort.
%
Ave: (flock size) Hen-day Lbs. feed/doz. prod. eggs
%
30 60 100
53.5 50.8 49.0
16.9 15.6 17.7
8.50 7.37 7.29
58.9 52.9 56.6
13.6 20.1 15.4
7.10 7.15 6.78
58.0 55.3 52.1
19.0 13.4 17.4
7.56 7.23 7.41
56.8 53.0 52.5
Ave. (floor space)
51.1
16.7
7.72
56.1
16.5
7.01
55.1
16.1
7.40
-
it is of interest that the 30-bird flocks had a higher percent production than the 60- or 100-bird flocks at all three bird densities. Again, the greatest production difference was provided by a comparison of the 30bird pens versus the two larger sizes. There was no evidence of a flock size X flock density interaction. The feed efficiency data indicated only significant differences among years. However, these data, shown in Table 1, agree with the production differences among flock densities with the better production groups usually showing the better efficiency. A reversal of this foregoing trend is shown in the flock size data. Here the smaller pen size, thirty birds, has the poorer efficiency in spite of better production. This relationship exists within all three flock densities. The mortality results are presented in Table 1 and it can be seen that no consistTABLE 2.—Analysis of variance of egg production and feed efficiency
Source
Dif.
Mean
Mean
square,
square, feed/doz eggs
egg
prod.
Total Floor space Flock size Years Floor space X flock size Floor spaceXyears Years X size Floor space X flock size Xyears
*P<.05. **P<.01.
26 2 2 2 4 4 4
%
Lbs. feed/doz. eggs
16.5 16.4 17.0
7.71 7.25 7.16
Mort.
-
ent mortality trends were evident in the three-year summary. All birds dying were subjected to post-mortem examination, and with the exception of the 1956-57 test year, when a rather severe chronic respiratory infection was evident, no serious disease problem existed. The major cause of mortality was the leucosis complex. Body weights were obtained during late February in 1957-58 and during March in the 1958-59 test year. The body weights for the 1957-58 year were significantly different for the flock-density treatments (P < .05) with the greater density pens having the lower weights. However, this relationship of body weight to pen-density was not evident in the 1958-59 data. Also, egg quality observations were made in both the 1957-58 and 1958-59 years. One such examination, Feb., 1958, indicated a significantly greater blood spot incidence at the high bird densities but subsequent studies later in the year and again during the 1958-59 season failed to substantiate this. There was no significant association of blood spots, meat spots, albumen height, or egg size with flock size or flock density. DISCUSSION
63.1* 49.3 177.9** 10.1 16.4
1.13 .81
7.48* .38
1.28
9.7
.13
14.1
.29
The interpretation of the results of pilot management studies such as reported herein requires caution. The results of any experiment with biological material are only applicable to the population studied and to the particular set of environmental conditions under which the experiment was
SPACE AND LAYING PERFORMANCE
conducted. Extrapolation of these results to all strains of chicken under all types and sizes of commercial operations would not be justified. The results of these studies have established that under the conditions of these experiments, increased numbers of birds per unit of floor space will cause a decrease in hen-day egg production. This reduction was not associated with any obvious environmental effects as all birds were housed on elevated slat floors to eliminate the litter problem. Feed, water, and nesting space were comparable among treatment groups. The air temperature and relative humidity were also quite uniform among pens due to the incomplete partitions separating the pens and the type of ventilation system employed. No attempt will be made to evaluate the economics of housing additional birds per unit of floor space. However, there was no substantial depression between two and three square foot allowances, with the significant reduction occurring between the one and two square foot per bird treatments. These results suggest the production response is not linearly relately to floor space allocation. This non-linearity of response causes further complication in extrapolation to the variety of housing and environmental conditions seen in commercial operations. These experiments provide some evidence that flock size may influence productive performance. The 30-bird pens were superior to the 60- and 100-bird pens at all three floor space densities. Again, extrapolation to commercial conditions is difficult as the largest pen size in these experiments would be considered very small in commercial flocks. However, the pen
899
size factor would be important in certain testing procedures such as Standard and Random Sample Testing programs. SUMMARY
1. Under the conditions of these experiments including slat floor and mechanical ventilation a floor space allowance of one square foot per bird significantly depressed hen-day egg production when compared to the two and three square foot per bird treatments. 2. Production differences between flock sizes (30, 60, and 100 birds) were not statistically significant, but approached significance, and the 30-bird flocks consistently had the best production regardless of floor space allocation. 3. No significant treatment effects on mortality were observed during the three year experiment. 4. No interaction of flock density with flock size was evident in these studies. REFERENCES Banks, E. M., and W. C. Allee, 1957. Some relations between flock size and agonistic behavior in domestic hens. Phys. Zool. 30: 255-268. Bressler, G. O., and H. V. Walton, 1956. The Penn State solar house. Pennsylvania Agr. Exp. Sta. Progress Report No. 162. Christian, J. J., and C. D. Lemunyan, 19S7. Adverse effects of crowding on reproduction and lactation of mice and two generations of their progeny. Naval Medical Research Institute Research Report, IS: 925-936. Guhl, A. M., 1953. Social behavior of the domestic fowl. Kansas Agr. Exp. Sta. Tech. Bui. 73: 1^8. Siegel, H. S., 19S8. Effects of increased population density on the adrenals of cockerels. Poultry Sci. 37: 1242. Siegel, H. S., 19S9. Egg production characteristics and adrenal function in White Leghorns confined at different floor space levels. Poultry Sci. 38:893-898.
OCTOBER 4-6. NEPPCO EXPOSITION AND CONVENTION, ONONDAGA WAR MEMORIAL AUDITORIUM, SYRACUSE, N.Y.