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The Correlation Between the Monthly Record of the First Year and the Annual Record of the Second Year, with Special Reference to Culling for Second Year Production.*
POULTRY SCIENCE VOL. I
June-July, 1922
No. 5
J. ARTHUR HARRIS AND HARRY R. LEWIS
Cold Spring Harbor, Long Island, and Davisville, R. I. In another place (Harris and Lewis, 1921) we have shown that the correlation between the first and second year egg laying record of the White Leghorn fowl is sufEciently high that the mere information as to whether a bird is or is not laying in certain critical months of the first year furnishes some basis for culling for second year production. A detailed biométrie treatment of the problem of the correlation between the egg laying activity of the first and the second year is now in press (Harris and Lewis, 1922). In culling the flock either for the purpose of eliminating the birds which will not lay further during the pullet year or for the purpose of selecting the birds which will make the best records during the second year, or be the most suitable for use as breeders the second year, a certain per cent of the flock is divided off from the rest. The practical man desires to know what record would have been made on the average by the birds which are to be discarded, had they been kept, and what record will be made by those which are retained in the flock. It is upon a comparison of the differences between the fraction of the flock which is to be eliminated and that which is to be kept that he will most * Papers from the Station for Experimental Evolution, and paper no. 88 of the Journal Series, New Jersey Agricultural Experiment Station. The results here given are based on the data of the first Vineland International Egg Laying and Breeding Contest.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
T H E C O R R E L A T I O N B E T W E E N T H E MONTHLY RECORD OF T H E FIRST YEAR AND T H E ANNUAL RECORD OF T H E SECOND YEAR, W I T H SPECIAL R E F E R E N C E TO CULLING FOR SECOND YEAR PRODUCTION.*
146
POULTRY
SCIENCE
TABLE I Total Eggs for First Year
Total Eggs for Second Year
Eggs Laid in April
No. of Birds
I 2
I I I
.226 .226 .226
.226 •452 .678
99-999 99-773 99-547
107 91
149 129
I
.226
.904
99-321
142
103
3
.677
'i.'sSi
99-095
301
277
I
.226
'1.807
98.418
142
141
I
2-033 2.936 3-839 5-193 7.676 11.965 16.028 24.606 37.02 Γ 52.822 70.429 84.650 93.002 98.645 99-322 99-999
98.192 97.966 97.063 96.160 94.806 92.323 88.034 83-971 75-393 62.978 47-177 29-570 15-349 6.997 1-354 .677
141 440 494 800
153 565 387 652
38 55 70 78 63 37 25 3 3
.226 •903 •903 1-354 2.483 4.289 4.063 8.578 12.415 15.801 17.607 14 221 8.152 5-643 0.677 0.677
1654 2797 2949 5998 939' 12322 14395 11825 7271 4586
1740 2396 2473 5178 7362 9596 11208 9205 5790 36II
591
663
358 454
44?
99-999
( lOO.OQÎ
{100.001
77103
61927
3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
4 4 6 II 19 18
Percent of Flock
Sum of Percentages
Sum of Percentages
3
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
probably base his decision concerning the advantages or the futility of the segregation of t h e theoretically better and poorer fractions of the flock upon the basis of such criteria as are avail able. T h i s may be accomplished by proceeding in the simple empir ical m a n n e r followed in an earlier discussion of first year produc tion in the W h i t e Leghorn ( H a r r i s , Blakeslee, and Kirkpatrick, 1918, p . 38-44.)· W h i l e our purpose in t h e present paper is to consider the results to be expected from birds in their second 5^ear when t h e y h a v e been selected on the basis of their first year performance, we shall also give the average first year productions of the groups of birds considered. I n w o r k i n g w i t h the record of the production of the individual m o n t h s of the first year as a basis of selection, we first reduce the actual numbers of birds laying given numbers of eggs in any
THE CORRELATION
BETWEEN
RECORDS
147
TABLE 2 Quarter of flock Selected
DECEMBER NOVEMBBR Record Percent First Second Record Percent First 1 Second of year year for for of year year month fiock average average month flock average average
Lovyest
O-I
24.4
144.0
Second
2-11
26.0
Third Highest
12-16 17-25
128.5
O-I
25-5
143-1
128.1
168.1
140.9
2-10
25-1
160.0
131-9
23.0
182.4
140.9
II-17
24.6
182.6
145.8
26.6
200.2
148.1
18-27
24.8
211 5
153-8
TABLE 3 Quarter of flock selected
JANUARY
FEBRUARY
Record Percent! First 1 Second Record Percent First Second of 1 year year for year year for of month flock I average average month flock average average
Lowest
o-I
24.4
142.7
125 7
0-7
24.8
149.8
129.3
Second
2-9
25-5
162.6
134-6
8-13
26.0
159-6
129.8
10-16 23-9
178.8
143.0
184.0
144.9
Third
1 4 - 1 6 23-3
Highest 210.1 I.55-0 155-3 17-25 26.2 * Of course divisions into equal fractions can only be attained by fitting a theoretical frequency curve to the yields of the individual mouths. Since this method of division will be used primarily for the practical purposes of separating a flock it seems best to make use of merely t h e groups which are given by the actual classes of eggs and their frequencies. 17-22
26.0
202.g
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
mouth of the first year to percentages. These relative frequencies may be summed from either end of their range, and be used to divide the flock into groups of any approximate relative size. The total production for the first and for the second year is given for each group, and these total productions, together with the actual frequencies, make possible the determination of the average second year production of groups of birds constituting any desired fraction of the flock. Table I illustrates the method of dividing the flock into quarters. The second column shows the frequency of birds laying various numbers of eggs in the given month, as shown in the first column. These actual frequencies are reduced to percentages in the third column. These percentage frequencies may be summed from either the lowest to the highest or from the highest to the lowest class, as in columns four and five of the table. From these columns it is quite easy to divide the flocks into groups of approximately any required size.* Finally the two
148
POULTRY
SCIENCE
TABLE ^ Quarter selected
MARCH
APRIL
Record Percent First Second Record Percent First Second of for year of year year year for month flock average average month fiock average average
Lowest
0-19
28.9
148.5
127.6
0-20
24.5
147.3
131.6
Second
20-21
27-5
172.2
139-3
21-22
28.2
173.7
135.7
22
16.0
185.5
144.7
23
17.6
184.6
143.7
23-28
27-5
196.0
150.2
24-28
29.6
190.4
148.2
Third Highest
JUNE Record Percent First 1 Second Record Percent First Second year of for year of of year ! year fiock average average month flock average average month MAY
Lowest
0-20
23.3
147.5
125.7
0-19
21.0
143.3
122,0
Second
21-22
20.8
169.0
Ï31.9
20-22
27.8
169.9
134.9
Third
23-24
30.0
180.2
144.0
23-24
293
182.0
140.7
25-30
26.0
25-30
21.9
198.2
161.9
Highest
T94.7
153.8
TABLE 6 Quarter of flock selected
AUGUST JULY Record Percent First Second Record Percent First Second year of year of year for year for month flock average average month flock average average
Lowest
0-18
23.9
143.4
I19.4
O-II
23-9
139.9
1x6.4
Second
19-21
20.8
168.5
134.0
12-17
20.1
166.9
136.5
Third
22-23
29.8
179.3
142.6
18-20
26.6
176.0
138.4
Highest
24 29
25.5
201.2
160.3
21-27
293
205.1
162.4
TABLE 7 Quarter of flock selected
OCTOBER
SEPTEMBER
Record Percent First Second Record Percent First Second year year year for of year for of month flock average average month flock average average
Lowest
0
33-2
147.8
124.3
Second
1-2
16.0
161.7
133.6
Third*
3-13
26.0
177.8
146.5
1-6
63.2
156.9
J29.8
II.7
187.0
145-7
211.2 162.3 14-24 24.8 7-24 25.1 Highest* 213.3 157.4 * T h e h i g h e s t half, t h e c o m b i n a t i o n of t h e t h i r d a n d h i g h e s t q u a r t e r g i v e s a s e c o n d y e a r a v e r a g e of 156.9.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
TABLE 5 Quarter of flock selected
THE CORRELATION
BETWEEN
RECORDS
149
TABLE SEPTEMBER
First Second Record Percent year year of for average average m o n t h flock
Quarter of flock selected
0-2
49.2
152.3
127.3
..
3-13
26.0
177.8
146.5
___
14-24
24.8
2133
157-4
Lowest and second Third* . . Highest* .
._
*The highest half, the combination of the third and highest quarter gives a second year average of 151.8. t T h e results already published in tables 7A to 7D for the Storrs series are not included here for comparison, because of differences in t h e range of number of eggs included in the different groups.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
last columns show the total eggs laid in the first and second year by birds of the various classes. The results for the twelve months of the year are shown in tables 2 to 7. While we are here concerned primarily with the problem of the record to be expected in the second year from groups of birds selected in the first year, it seems desirable to give the results for both first and second year total production. The first year entries of tables 2 to 7 correspond, therefore, to those given in tables 7A to 7D of a former paper (Harris, Blakeslee, and Kirkpatrick, 1918, p. 41). They serve to confirm on the data of the Vineland contest the conclusions drawn from studies made on the Storrs data. The values for the second year are given here for the first time.f These tables show that without exception the first year average increases from the lowest-performing to the highest-performing quarter of the flock as determined by the record of each of the twelve months used as a basis of selection. The results are, therefore, in full agreement with those found in our earlier investigations based on the International Egg Laying Contest at Storrs. The differences between the lowest and the highest quarter are very material^ ranging from 43.1 eggs in April to 68.4 eggs in December. For the Storrs series already quoted the range of the differences is from 37.6 eggs in November (when the lowest and the second group were combined) to 73.0 in September. The agreement is excellent, but the months in which the maximum
150
POULTRY
SCIENCE
T h u s while the differences secured in the second year production of the flock due to culling in any month in the first year are not so large as those found in the first year they are in all cases of material size. I n September and October it is difficult to divide the fiock into q u a r t e r s because of the very large proportion of the birds which are not laying in these two final m o n t h s of the year. T h u s 63.2 per cent of the birds lay no eggs in October while 33.2 per cent lay no eggs in September. If we divide the flocks into halves in these two m o n t h s as shown in table 7 for October and in the following table 8 for September we find t h a t the lower half of the flock lays about 128-130 eggs d u r i n g the second year, whereas the upper half of the flock (not shown separately in the tables) lays 151.8 eggs when classified by September production and 156.9 eggs when classified by October production. REFERENCES Harris, J. Arthur and Lewis, H. R. The second year record of birds which did and which did not lay during individual months of the pullet year. Science, N. S., 54:224-226, 1921. Harris, J. Arthur and î^ewis, H. R. The correlation between first and second year egg Jirodiiction in the domestic fowl. Genetics. In press. Harris, J. Arthur, Blakeslee, A. F . , and Kirkpatrick, W. F . T h e correlation between egg production during various periods of the year in t h e domestic fowl. Genetics, 3:27-72 ; fig i - i i . 1918.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
and minimum differences are found are not the same in the two series. T h e results which concern us primarily in this place are those for second year production. W e note t h a t practically without exception the same rule holds. T h e egg production for the second year increases from the lowest to t h e highe.st quarter of the flock as determined by an examination of the birds in any month of the first year. T h e differences in the second year are not, however, as large as those in the first year. T h e differences between the average second year production for the lowest and the highest group of the flock range from 16.6 eggs for April to 46.0 for A u g u s t .
June-July, 1922
No. 5
J. ARTHUR HARRIS AND HARRY R. LEWIS
Cold Spring Harbor, Long Island, and Davisville, R. I. In another place (Harris and Lewis, 1921) we have shown that the correlation between the first and second year egg laying record of the White Leghorn fowl is sufEciently high that the mere information as to whether a bird is or is not laying in certain critical months of the first year furnishes some basis for culling for second year production. A detailed biométrie treatment of the problem of the correlation between the egg laying activity of the first and the second year is now in press (Harris and Lewis, 1922). In culling the flock either for the purpose of eliminating the birds which will not lay further during the pullet year or for the purpose of selecting the birds which will make the best records during the second year, or be the most suitable for use as breeders the second year, a certain per cent of the flock is divided off from the rest. The practical man desires to know what record would have been made on the average by the birds which are to be discarded, had they been kept, and what record will be made by those which are retained in the flock. It is upon a comparison of the differences between the fraction of the flock which is to be eliminated and that which is to be kept that he will most * Papers from the Station for Experimental Evolution, and paper no. 88 of the Journal Series, New Jersey Agricultural Experiment Station. The results here given are based on the data of the first Vineland International Egg Laying and Breeding Contest.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
T H E C O R R E L A T I O N B E T W E E N T H E MONTHLY RECORD OF T H E FIRST YEAR AND T H E ANNUAL RECORD OF T H E SECOND YEAR, W I T H SPECIAL R E F E R E N C E TO CULLING FOR SECOND YEAR PRODUCTION.*
146
POULTRY
SCIENCE
TABLE I Total Eggs for First Year
Total Eggs for Second Year
Eggs Laid in April
No. of Birds
I 2
I I I
.226 .226 .226
.226 •452 .678
99-999 99-773 99-547
107 91
149 129
I
.226
.904
99-321
142
103
3
.677
'i.'sSi
99-095
301
277
I
.226
'1.807
98.418
142
141
I
2-033 2.936 3-839 5-193 7.676 11.965 16.028 24.606 37.02 Γ 52.822 70.429 84.650 93.002 98.645 99-322 99-999
98.192 97.966 97.063 96.160 94.806 92.323 88.034 83-971 75-393 62.978 47-177 29-570 15-349 6.997 1-354 .677
141 440 494 800
153 565 387 652
38 55 70 78 63 37 25 3 3
.226 •903 •903 1-354 2.483 4.289 4.063 8.578 12.415 15.801 17.607 14 221 8.152 5-643 0.677 0.677
1654 2797 2949 5998 939' 12322 14395 11825 7271 4586
1740 2396 2473 5178 7362 9596 11208 9205 5790 36II
591
663
358 454
44?
99-999
( lOO.OQÎ
{100.001
77103
61927
3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
4 4 6 II 19 18
Percent of Flock
Sum of Percentages
Sum of Percentages
3
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
probably base his decision concerning the advantages or the futility of the segregation of t h e theoretically better and poorer fractions of the flock upon the basis of such criteria as are avail able. T h i s may be accomplished by proceeding in the simple empir ical m a n n e r followed in an earlier discussion of first year produc tion in the W h i t e Leghorn ( H a r r i s , Blakeslee, and Kirkpatrick, 1918, p . 38-44.)· W h i l e our purpose in t h e present paper is to consider the results to be expected from birds in their second 5^ear when t h e y h a v e been selected on the basis of their first year performance, we shall also give the average first year productions of the groups of birds considered. I n w o r k i n g w i t h the record of the production of the individual m o n t h s of the first year as a basis of selection, we first reduce the actual numbers of birds laying given numbers of eggs in any
THE CORRELATION
BETWEEN
RECORDS
147
TABLE 2 Quarter of flock Selected
DECEMBER NOVEMBBR Record Percent First Second Record Percent First 1 Second of year year for for of year year month fiock average average month flock average average
Lovyest
O-I
24.4
144.0
Second
2-11
26.0
Third Highest
12-16 17-25
128.5
O-I
25-5
143-1
128.1
168.1
140.9
2-10
25-1
160.0
131-9
23.0
182.4
140.9
II-17
24.6
182.6
145.8
26.6
200.2
148.1
18-27
24.8
211 5
153-8
TABLE 3 Quarter of flock selected
JANUARY
FEBRUARY
Record Percent! First 1 Second Record Percent First Second of 1 year year for year year for of month flock I average average month flock average average
Lowest
o-I
24.4
142.7
125 7
0-7
24.8
149.8
129.3
Second
2-9
25-5
162.6
134-6
8-13
26.0
159-6
129.8
10-16 23-9
178.8
143.0
184.0
144.9
Third
1 4 - 1 6 23-3
Highest 210.1 I.55-0 155-3 17-25 26.2 * Of course divisions into equal fractions can only be attained by fitting a theoretical frequency curve to the yields of the individual mouths. Since this method of division will be used primarily for the practical purposes of separating a flock it seems best to make use of merely t h e groups which are given by the actual classes of eggs and their frequencies. 17-22
26.0
202.g
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
mouth of the first year to percentages. These relative frequencies may be summed from either end of their range, and be used to divide the flock into groups of any approximate relative size. The total production for the first and for the second year is given for each group, and these total productions, together with the actual frequencies, make possible the determination of the average second year production of groups of birds constituting any desired fraction of the flock. Table I illustrates the method of dividing the flock into quarters. The second column shows the frequency of birds laying various numbers of eggs in the given month, as shown in the first column. These actual frequencies are reduced to percentages in the third column. These percentage frequencies may be summed from either the lowest to the highest or from the highest to the lowest class, as in columns four and five of the table. From these columns it is quite easy to divide the flocks into groups of approximately any required size.* Finally the two
148
POULTRY
SCIENCE
TABLE ^ Quarter selected
MARCH
APRIL
Record Percent First Second Record Percent First Second of for year of year year year for month flock average average month fiock average average
Lowest
0-19
28.9
148.5
127.6
0-20
24.5
147.3
131.6
Second
20-21
27-5
172.2
139-3
21-22
28.2
173.7
135.7
22
16.0
185.5
144.7
23
17.6
184.6
143.7
23-28
27-5
196.0
150.2
24-28
29.6
190.4
148.2
Third Highest
JUNE Record Percent First 1 Second Record Percent First Second year of for year of of year ! year fiock average average month flock average average month MAY
Lowest
0-20
23.3
147.5
125.7
0-19
21.0
143.3
122,0
Second
21-22
20.8
169.0
Ï31.9
20-22
27.8
169.9
134.9
Third
23-24
30.0
180.2
144.0
23-24
293
182.0
140.7
25-30
26.0
25-30
21.9
198.2
161.9
Highest
T94.7
153.8
TABLE 6 Quarter of flock selected
AUGUST JULY Record Percent First Second Record Percent First Second year of year of year for year for month flock average average month flock average average
Lowest
0-18
23.9
143.4
I19.4
O-II
23-9
139.9
1x6.4
Second
19-21
20.8
168.5
134.0
12-17
20.1
166.9
136.5
Third
22-23
29.8
179.3
142.6
18-20
26.6
176.0
138.4
Highest
24 29
25.5
201.2
160.3
21-27
293
205.1
162.4
TABLE 7 Quarter of flock selected
OCTOBER
SEPTEMBER
Record Percent First Second Record Percent First Second year year year for of year for of month flock average average month flock average average
Lowest
0
33-2
147.8
124.3
Second
1-2
16.0
161.7
133.6
Third*
3-13
26.0
177.8
146.5
1-6
63.2
156.9
J29.8
II.7
187.0
145-7
211.2 162.3 14-24 24.8 7-24 25.1 Highest* 213.3 157.4 * T h e h i g h e s t half, t h e c o m b i n a t i o n of t h e t h i r d a n d h i g h e s t q u a r t e r g i v e s a s e c o n d y e a r a v e r a g e of 156.9.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
TABLE 5 Quarter of flock selected
THE CORRELATION
BETWEEN
RECORDS
149
TABLE SEPTEMBER
First Second Record Percent year year of for average average m o n t h flock
Quarter of flock selected
0-2
49.2
152.3
127.3
..
3-13
26.0
177.8
146.5
___
14-24
24.8
2133
157-4
Lowest and second Third* . . Highest* .
._
*The highest half, the combination of the third and highest quarter gives a second year average of 151.8. t T h e results already published in tables 7A to 7D for the Storrs series are not included here for comparison, because of differences in t h e range of number of eggs included in the different groups.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
last columns show the total eggs laid in the first and second year by birds of the various classes. The results for the twelve months of the year are shown in tables 2 to 7. While we are here concerned primarily with the problem of the record to be expected in the second year from groups of birds selected in the first year, it seems desirable to give the results for both first and second year total production. The first year entries of tables 2 to 7 correspond, therefore, to those given in tables 7A to 7D of a former paper (Harris, Blakeslee, and Kirkpatrick, 1918, p. 41). They serve to confirm on the data of the Vineland contest the conclusions drawn from studies made on the Storrs data. The values for the second year are given here for the first time.f These tables show that without exception the first year average increases from the lowest-performing to the highest-performing quarter of the flock as determined by the record of each of the twelve months used as a basis of selection. The results are, therefore, in full agreement with those found in our earlier investigations based on the International Egg Laying Contest at Storrs. The differences between the lowest and the highest quarter are very material^ ranging from 43.1 eggs in April to 68.4 eggs in December. For the Storrs series already quoted the range of the differences is from 37.6 eggs in November (when the lowest and the second group were combined) to 73.0 in September. The agreement is excellent, but the months in which the maximum
150
POULTRY
SCIENCE
T h u s while the differences secured in the second year production of the flock due to culling in any month in the first year are not so large as those found in the first year they are in all cases of material size. I n September and October it is difficult to divide the fiock into q u a r t e r s because of the very large proportion of the birds which are not laying in these two final m o n t h s of the year. T h u s 63.2 per cent of the birds lay no eggs in October while 33.2 per cent lay no eggs in September. If we divide the flocks into halves in these two m o n t h s as shown in table 7 for October and in the following table 8 for September we find t h a t the lower half of the flock lays about 128-130 eggs d u r i n g the second year, whereas the upper half of the flock (not shown separately in the tables) lays 151.8 eggs when classified by September production and 156.9 eggs when classified by October production. REFERENCES Harris, J. Arthur and Lewis, H. R. The second year record of birds which did and which did not lay during individual months of the pullet year. Science, N. S., 54:224-226, 1921. Harris, J. Arthur and î^ewis, H. R. The correlation between first and second year egg Jirodiiction in the domestic fowl. Genetics. In press. Harris, J. Arthur, Blakeslee, A. F . , and Kirkpatrick, W. F . T h e correlation between egg production during various periods of the year in t h e domestic fowl. Genetics, 3:27-72 ; fig i - i i . 1918.
Downloaded from http://ps.oxfordjournals.org/ at Ritsumeikan University on June 8, 2015
and minimum differences are found are not the same in the two series. T h e results which concern us primarily in this place are those for second year production. W e note t h a t practically without exception the same rule holds. T h e egg production for the second year increases from the lowest to t h e highe.st quarter of the flock as determined by an examination of the birds in any month of the first year. T h e differences in the second year are not, however, as large as those in the first year. T h e differences between the average second year production for the lowest and the highest group of the flock range from 16.6 eggs for April to 46.0 for A u g u s t .