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Variation in the Growth-Rate of Experimental Birds
461
RESEARCH NOTES
methods should yield very interesting information. MORRIS STEGGERDA W. F. HOLLANDER Department of Genetics Carnegie Institution of Washington Cold Spring Harbor, New York Received for publication July 27, 1944. REFERENCE
Hall, G. O. 1944. Egg shell color in crosses between white- and brown-egg breeds. Poultry Sci. 23:259-265.
VARIATION IN THE GROWTH-RATE OF EXPERIMENTAL BIRDS One of the difficulties with which the small, tends to obscure the effect on growth experimenter, who is conducting poultry by the ration under study and renders it feeding trials, must contend, is the great difficult to satisfactorily interpret the results of the experiment. Under such cirTABLE 1.—Ration composition cumstances, even the application of a statistical analysis to the data is not entirely Ration Ration Ingredient B satisfactory, and the investigator, if he A is to draw reliable conclusions from his ex20.00 15.00 Ground yellow corn 10.00 10.00 periments must minimize the influence of Wheat bran 10.00 5.00 Wheat shorts this variation by the use of a large number 10.00 10.00 Ground wheat 10.00 5.00 Rolled oat groats of birds per group. 10.00 12.00 Ground whole oats As pointed out by Schroeder and Law2.25 19.80 Ground barley 3.00 4.00 Dehydrated alfalfa rence (1943) the use of a sufficiently large 1.00 Cereal grass number of birds to permit the accurate' 2.50 Fish meal (65%) 5.00 3.00 Meat meal (50%) interpretation of results is a factor which 7.00 8.00 Soybean oil meal is too often disregarded in feeding trials. 5.00 2.00 Buttermilk powder 2.50 3.50 Oyster shell (fine) Undoubtedly, many of the failures to dupli0.50 0.50 Salt (iodized and manganized) cate the results of an experiment may be 1.00 1.00 Grit (insol.) 0.20 0.25 Cod liver oil (400 D 3000 A) traced to this factor, particularly if the 1.00 Steamed bone meal differences in growth due to the influence Totals 100.00 100.00 of the rations under study are relatively small. Crude protein percent 19.5 16.5 1200 Riboflavin (micrograms per lb.) 1670 Some data relating to this problem have been accumulated in the authors' laboravariability in growth exhibited by birds fed tory. While the data are not extensive they the same ration and reared, as far as pos- do illustrate very clearly the importance sible, under identical conditions. This diffi- of the above considerations, and are, thereculty, especially if the group sizes are fore, considered to be of sufficient interest
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
cause of the flattened egg shapes? Was there some pressure from crowding of the hen's internal organs in some way, or was one side of the shell-secreting region of the oviduct defective? At any rate, these shapes seem good evidence that rotation of the egg does not occur during shell formation, as suggested by some oologists. If such peculiarities are as common as indicated by their frequency in this small flock, a more extensive study of them in large populations and with laboratory
462
RESEARCH NOTES TABLE 2.—Variation in the average weight of 10-week-old chicks fed ration A Females Av. Wt. gms.
Standard Deviation
Total Feed Consumption lbs.
16 17
926.6 947.6
119.26 103.76
269 256
Males Row in Battery
Pen
1
1 2
Av. Wt. gms.
Standard Deviation
18 17
1111.9 1083.8
71.77 136.13
No. .
No.
3 4
18 16
1086.7 1136.9
140.18 115.51
16 18
948.1 999.2
94.71 95.91
265 255
3
5 6
16
1053.1
132.71
18
934.7
147.74
256
4
7 8
17 17
1026.2 975.6
135.51 171.12
18 17
878.1 902.9
119.99 142.65
252 252
5
9 10
18 20
1035.0 1012.0
160.24 191.97
16 15
891.6 904.3
119.70 171.18
257 265
1056.9 161.3
148.59
151
926.4 121.1
12735.
Total
157 Range
to present in this communication. Nineteen groups of day-old Barred Rock chicks (approximately 17 male and 17 female birds in each group) were selected at random from a large batch of chicks. The hens from which these chicks were obtained were of the same strain and fed the same ration, mash ad lib, and whole grain sup-
plied in quantities sufficient to make up
SO percent of the feed consumed. The chicks were weighed individually and placed in electrically heated battery brooders in an air conditioned building, the temperature of which was thermostatically controlled at approximately 80°F, Two battery brooders were used in the experi-
TABLE 3.—Variation in the average weight of 10-week-old chicks fed ration B
Av. Wt. gms.
Standard Deviation
No.
Av. Wt. gms.
Standard Deviation
Total Feed Consumption lbs.
15 17
951.0 992.6
156.74 110.77
20 14
864.2 860.3
100.70 88.61
252 252
3 4
17 19
1009.4 899.2
143.50 179.89
15 13
866.3 867.7
120.58 138.01
252 252
3
5 6
16 17
929.4 918.2
170.64 116.09
17 17
909.7 840.0
105.90 136.42
249 252
4
7 8
16 21
1004.1 976.9
121.19 191.11
14 12
852.1 845.0
117.48 115.72
245 252
5
9 10
16 19
969.4 902.7
157.98 125.90
17 13
845.6 956.5
142.00 112.55
251 251
954.0 110.2
150.75
152
870.0 116.5
119.01
Females
Males Row in Battery
Pen
1
1 2
2
No.
Total
173 Range
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
2
463
RESEARCH NOTES
number 1. There appears to be no evidence that the position of the pen in the battery influenced the result. Obviously a group size of 15 to 20 birds, even when fed under such uniform conditions as described for this experiment, is too small to permit a satisfactory measure of the growth promoting value of different rations. It can readily be seen that erroneous conclusions regarding the relative feeding value of ration A and ration B could have been drawn had certain groups been used for comparison. This is especially significant when the wide difference in the feeding value of the two rations is considered. D. C. HILL S. J. SLINGEE I . MOTZOK Nutrition and Poultry
Departments of Animal Husbandry Ontario Agricultural College Guelph, Canada Received for publication July 28, 1944. REFERENCE
Schroeder, C. H. and H. B. Lawrence, 1932. The number of chicks required to demonstrate the significance of growth differences. Poultry Sci., 11:208-218.
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
ment, each consisting of a tier of five double pens. Nine groups were placed in one battery and fed a good starter ration (ration A) and 10 groups were placed in the other and fed a ration less adequate with respect to the level of protein and of riboflavin (ration B). The composition of the rations is given in Table 1. The chicks were weighed at weekly intervals throughout a 10-week feeding period. The rations in the form of a dry mash were kept before the birds at all times. The results are presented in Table 2 and Table 3. Pen numbers 1 and 2, 3 and 4, etc., represent the paired pens in descending order from the top of the battery. The most interesting observation to be made from the data is the wide range in average weights obtained for the various groups. This range is widest for the male birds in battery number 1 in which the birds of pen number 4 averaged 1136.9 gm. and those of pen number 8 averaged 795.6 gm. It is also noteworthy that a few groups in battery number 2 in which the birds received the poorer ration exceeded the growth of certain groups in battery
RESEARCH NOTES
methods should yield very interesting information. MORRIS STEGGERDA W. F. HOLLANDER Department of Genetics Carnegie Institution of Washington Cold Spring Harbor, New York Received for publication July 27, 1944. REFERENCE
Hall, G. O. 1944. Egg shell color in crosses between white- and brown-egg breeds. Poultry Sci. 23:259-265.
VARIATION IN THE GROWTH-RATE OF EXPERIMENTAL BIRDS One of the difficulties with which the small, tends to obscure the effect on growth experimenter, who is conducting poultry by the ration under study and renders it feeding trials, must contend, is the great difficult to satisfactorily interpret the results of the experiment. Under such cirTABLE 1.—Ration composition cumstances, even the application of a statistical analysis to the data is not entirely Ration Ration Ingredient B satisfactory, and the investigator, if he A is to draw reliable conclusions from his ex20.00 15.00 Ground yellow corn 10.00 10.00 periments must minimize the influence of Wheat bran 10.00 5.00 Wheat shorts this variation by the use of a large number 10.00 10.00 Ground wheat 10.00 5.00 Rolled oat groats of birds per group. 10.00 12.00 Ground whole oats As pointed out by Schroeder and Law2.25 19.80 Ground barley 3.00 4.00 Dehydrated alfalfa rence (1943) the use of a sufficiently large 1.00 Cereal grass number of birds to permit the accurate' 2.50 Fish meal (65%) 5.00 3.00 Meat meal (50%) interpretation of results is a factor which 7.00 8.00 Soybean oil meal is too often disregarded in feeding trials. 5.00 2.00 Buttermilk powder 2.50 3.50 Oyster shell (fine) Undoubtedly, many of the failures to dupli0.50 0.50 Salt (iodized and manganized) cate the results of an experiment may be 1.00 1.00 Grit (insol.) 0.20 0.25 Cod liver oil (400 D 3000 A) traced to this factor, particularly if the 1.00 Steamed bone meal differences in growth due to the influence Totals 100.00 100.00 of the rations under study are relatively small. Crude protein percent 19.5 16.5 1200 Riboflavin (micrograms per lb.) 1670 Some data relating to this problem have been accumulated in the authors' laboravariability in growth exhibited by birds fed tory. While the data are not extensive they the same ration and reared, as far as pos- do illustrate very clearly the importance sible, under identical conditions. This diffi- of the above considerations, and are, thereculty, especially if the group sizes are fore, considered to be of sufficient interest
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
cause of the flattened egg shapes? Was there some pressure from crowding of the hen's internal organs in some way, or was one side of the shell-secreting region of the oviduct defective? At any rate, these shapes seem good evidence that rotation of the egg does not occur during shell formation, as suggested by some oologists. If such peculiarities are as common as indicated by their frequency in this small flock, a more extensive study of them in large populations and with laboratory
462
RESEARCH NOTES TABLE 2.—Variation in the average weight of 10-week-old chicks fed ration A Females Av. Wt. gms.
Standard Deviation
Total Feed Consumption lbs.
16 17
926.6 947.6
119.26 103.76
269 256
Males Row in Battery
Pen
1
1 2
Av. Wt. gms.
Standard Deviation
18 17
1111.9 1083.8
71.77 136.13
No. .
No.
3 4
18 16
1086.7 1136.9
140.18 115.51
16 18
948.1 999.2
94.71 95.91
265 255
3
5 6
16
1053.1
132.71
18
934.7
147.74
256
4
7 8
17 17
1026.2 975.6
135.51 171.12
18 17
878.1 902.9
119.99 142.65
252 252
5
9 10
18 20
1035.0 1012.0
160.24 191.97
16 15
891.6 904.3
119.70 171.18
257 265
1056.9 161.3
148.59
151
926.4 121.1
12735.
Total
157 Range
to present in this communication. Nineteen groups of day-old Barred Rock chicks (approximately 17 male and 17 female birds in each group) were selected at random from a large batch of chicks. The hens from which these chicks were obtained were of the same strain and fed the same ration, mash ad lib, and whole grain sup-
plied in quantities sufficient to make up
SO percent of the feed consumed. The chicks were weighed individually and placed in electrically heated battery brooders in an air conditioned building, the temperature of which was thermostatically controlled at approximately 80°F, Two battery brooders were used in the experi-
TABLE 3.—Variation in the average weight of 10-week-old chicks fed ration B
Av. Wt. gms.
Standard Deviation
No.
Av. Wt. gms.
Standard Deviation
Total Feed Consumption lbs.
15 17
951.0 992.6
156.74 110.77
20 14
864.2 860.3
100.70 88.61
252 252
3 4
17 19
1009.4 899.2
143.50 179.89
15 13
866.3 867.7
120.58 138.01
252 252
3
5 6
16 17
929.4 918.2
170.64 116.09
17 17
909.7 840.0
105.90 136.42
249 252
4
7 8
16 21
1004.1 976.9
121.19 191.11
14 12
852.1 845.0
117.48 115.72
245 252
5
9 10
16 19
969.4 902.7
157.98 125.90
17 13
845.6 956.5
142.00 112.55
251 251
954.0 110.2
150.75
152
870.0 116.5
119.01
Females
Males Row in Battery
Pen
1
1 2
2
No.
Total
173 Range
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
2
463
RESEARCH NOTES
number 1. There appears to be no evidence that the position of the pen in the battery influenced the result. Obviously a group size of 15 to 20 birds, even when fed under such uniform conditions as described for this experiment, is too small to permit a satisfactory measure of the growth promoting value of different rations. It can readily be seen that erroneous conclusions regarding the relative feeding value of ration A and ration B could have been drawn had certain groups been used for comparison. This is especially significant when the wide difference in the feeding value of the two rations is considered. D. C. HILL S. J. SLINGEE I . MOTZOK Nutrition and Poultry
Departments of Animal Husbandry Ontario Agricultural College Guelph, Canada Received for publication July 28, 1944. REFERENCE
Schroeder, C. H. and H. B. Lawrence, 1932. The number of chicks required to demonstrate the significance of growth differences. Poultry Sci., 11:208-218.
Downloaded from http://ps.oxfordjournals.org/ at New York Universtiy Law School Library on April 11, 2015
ment, each consisting of a tier of five double pens. Nine groups were placed in one battery and fed a good starter ration (ration A) and 10 groups were placed in the other and fed a ration less adequate with respect to the level of protein and of riboflavin (ration B). The composition of the rations is given in Table 1. The chicks were weighed at weekly intervals throughout a 10-week feeding period. The rations in the form of a dry mash were kept before the birds at all times. The results are presented in Table 2 and Table 3. Pen numbers 1 and 2, 3 and 4, etc., represent the paired pens in descending order from the top of the battery. The most interesting observation to be made from the data is the wide range in average weights obtained for the various groups. This range is widest for the male birds in battery number 1 in which the birds of pen number 4 averaged 1136.9 gm. and those of pen number 8 averaged 795.6 gm. It is also noteworthy that a few groups in battery number 2 in which the birds received the poorer ration exceeded the growth of certain groups in battery