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Progeny Testing in Breeding for Egg Production
Progeny Testing in Breeding for Egg Production MORLEY A. JULL Bureau of Animal Industry, U. 5. Department of Agriculture, Washington, D.C. (Received for Publication March 29, 1933)
T
marked degree a standard-bred defect. A first-year record constitutes the number of eggs laid by a bird in 365 days from the date of laying the first egg. During the three years there were 1,033 birds placed in the laying houses. The only records omitted were those of birds that died, mortality amounting to 13.26 percent. The 896 daughters that completed their first year of laying averaged 192.85 eggs each. The average egg production per bird during each of three years was practically the same, viz.: 192.17, 193.50, and 192.84. The environmental conditions under which the daughters were kept during the three years were as nearly identical as it was possible to maintain. The hatching season each year occurred from March 17 to the last week in April, inclusive. Housing conditions were identical, the rations fed and the methods of feeding were the same, and the general methods of management were the same. During the winter months artificial lights were used in the morning. The breeding stock used each year consisted of males from dams that laid 225 or more eggs each and females that laid 225 or more eggs each in their first year of laying, provided, in addition, that the male and female in each case had a number of sisters with a relatively high average egg production. In other words, the selection of the breeding stock was confined to the progeny of the sires and dams that gave the best results in the previous year's breeding work. Other things than the number of eggs laid were also considered in the selection of the
144]
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HE most effective way of breeding to improve egg production is to select the breeding stock from among the progeny of sires and dams that have proved to be good breeders. Such a method of breeding constitutes what is known as progeny testing. Although progeny testing is practiced by a few of the most progressive poultry breeders in various countries, the great majority of breeders frequently base the selection of their breeding stock almost entirely on the records of egg production of the females. In the latter case a hen with a 280-egg record is claimed to be a much better breeder than a hen with a 220-egg record. Also, a male, the son of a 300-egg dam, is often claimed to be a much more valuable breeder than a male, the son of a 230-egg dam. That such is not necessarily the case is clearly borne out by the data presented here. Data are presented based on the results secured in breeding Single Comb White Leghorns by the progeny-test method at the United States Animal Husbandry Experiment Farm, Beltsville, Maryland. The results include the first-year egg records of daughters during the laying years 19281929, 1929-1930, and 1930-1931. All of the daughters that each dam produced each year were placed in the laying house, except (1) those physically unfit, (2) families of fullsisters of less than five (unless the dam had previously been determined to have produced superior progeny), and (3) a few cases in which all of the daughters of a given dam were discarded because the majority of her sons and daughters possessed to a
JANUARY,
1934.
VOL.
XIII, No. 1
breeding stock used each year. The size of egg laid by each female and by her fullsisters was also taken into consideration. In some cases entire families with high records were rejected because a majority of the fullsisters laid small eggs. Also, if a dam with good egg size produced daughters the majority of which laid small eggs, none of the daughters were used as breeders and the dam herself was rejected from the breeding pen. Males for breeding purposes were selected from families of full-sisters which laid
45
with the results secured in matings that produced at least three full-sisters per family. The average egg production per daughter for all daughters produced by 19 different sires is given in Table 1 together with the number of dams mated to each sire and their average egg production. There were 135 dams used and they produced 785 daughters. The data in Table 1 show that the daughters of sire No. 3 had the highest average egg production per daughter, 229, while the daughters of sire No. 50 had the lowest
Year
Sire No.
No. of dams
1928 1928 1928 1928 1928 1929 1929 1929 1929 1929 1929 1929 1930 1930 1930 1930 1930 1930 1930
3 50 91 100
7 5 8 8 8 4 6 6 13 8 10 6 8 7 10 6 5 4 6
10106
232 235 248 249 250 252 253 254 256 259 260 261 263 264
eggs of good size. The hatchability of each dam's eggs was also taken into consideration in the selection of pullets to place in the laying house and in the selection of sons and daughters for future breeding purposes. A dam having less than 75 percent hatchability of fertile eggs was regarded as a poor breeder. Then again, due consideration has been given to standard-bred qualities in the selection of breeders from among the progeny produced each year. In order to determine the significance of progeny testing in breeding for egg production the records treated in this article deal
Dams' average No. of daughters production
248 228 254 248 239 239 234 247 243 243 247 242 237 237 243 241 246 239 242
45 49 46 59 46 15 34 42 71 37 48 31 51 27 69 38 25 19 3i
Daughters' average production
229 168 199 193 179 183 184 173 206 227 200 179 179 204 185 199 179 199 206
average egg production per daughter, 168. Judging by the average egg production of the 19 different groups of daughters, it is apparent that either the sires or the dams or both sires and dams differed considerably in their breeding potentialities. Six sires, Nos. 3, 249, 250, 252, 256, and 264, produced daughters whose average egg production was over 200 eggs per daughter. Four sires, Nos. 91, 100, 260, and 263 produced daughters whose average egg production was between 190 and 200 eggs per daughter. Three sires, Nos. 232, 235, and 259 produced daughters whose average egg produc-
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TABLE 1.—Average egg production of daughters produced by 19 different sires, each mated to different groups of dams
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tion was between 180 and' 190 eggs per daughter. Five sires, Nos. 10106, 248, 253, 254, and 261 produced daughters whose average egg production was between 170 and 180 eggs per daughter. One sire, No. 50, produced daughters whose average egg production was less than 170 eggs per daughter. The fact that a dam's first-year record of egg production is not in itself a criterion of her breeding potentialities but that the kind of progeny she produces is determined large-
dam No. 3466 produced good progeny when mated to sires Nos. 50 and 249. Dam No. 3350 mated to sires Nos. 100 and 248 produced equally good progeny but dam No. 3472 produced much better progeny when mated to sire No. 100 than when mated to sire No. 248. Dam No. 3728 produced much better progeny when mated to male No. 91 than when mated to male No. 248 whereas dam No. 3845 produced much better progeny when mated to sire No. 248 than when mated to sire No. 91. The data in Table 2
Her production
Year
Sire
No. of daughters
Daughters' average production
2786
257
1927 1928 1929
46 50 249
5 5 4
217 159 228
3466
247
1928 1929
50 249
8 4
212 210
3350
246
1928 1929
100 248
9 5
200 198
3472
235
1928 1929
100 248
7 7
212 172
3728
258
1928 1929
91 248
5 3
213 167
3845
262
1928 1929
91 248
5 4
175 202
ly by the kind of mating involved is shown clearly by the results secured from dams which were mated to different males each year the dam was bred. In Table 2 is given the average egg production of each group of daughters produced by different dams selected at random each of which was mated to a different male each year she was bred. The data in Table 2 demonstrate that the kind of progeny produced by a given mating is determined by the particular kind of a mating it happens to be. Dam No. 2786 produced poor progeny when mated to sire No. 50 but good progeny when mated to sires Nos. 46 and 249. On the other hand,
tend to confirm the suggestion made previously that the egg production of a dam is not a criterion of her ability to produce good progeny. It follows, therefore, that in this group of selected sires the egg production of the sire's dam is apparently of little significance in determining his ability to produce good progeny; the validity of this statement is borne out by the results given in Table 2. It should be borne in mind that the two preceding sentences apply to the results secured from dams and sires selected rather rigidly on the basis of the egg production of their dams. The most important point brought out by
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 10, 2015
egg production of each group of daughters of dams mated to different males in different years
TABLE 2.—
Dam
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1934.
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47
XIII, No. 1
the data in Table 2 is that the kind of progeny produced determines the relative value of a given mating rather than the breeding potentiality of either a given sire or dam. In other Words, progeny testing determines the breeding potentiality of a given sire when mated to a given dam and of a given dam when mated to a given sire.
same sire produced uniform results whereas other groups of full-sisters mated to the same sire produced diverse results. Does the dam's record of egg production bear a significant relationship to the mean egg production of her daughters? In Table 4 the average egg production of the daughters of the dams whose egg production was
TABLE 3.—Average egg production of daughters produced by each of the different full-sisters mated to the same sire Dam*
Dam's production
No. of daughters
Daughters' average production
91
3640 3845
251 262
8 5
214 175
3-
3428 3693 3769
261 243 245
8 12 5
239 235 245
3
3614 3767 3824
272 250 236
2 6 7
238 219 232
50
3289 3695
237 232
11 11
180 194
250
4050 4128
229 252
9 3
220 228
250
4086 4350 4451
259 231 254
4 5 5
242 244 220
249
3287 3289 3695
230 237 232
5 6 8
225 182 207
260
4700 4817
240 228
3 4
182 205
261
4641 4658
225 243
3 10
176 205
264
5009 5014
225 247
4 5
206 231
* The pairs and trios of dams mated to each male represent full-sisters.
The fact that full-sisters mated to the same sire do not necessarily produce similar results is clearly demonstrated by the results given in Table 3. The results given in Table 3 show that from the standpoint of the average egg production of the daughters of each dam certain groups of full-sisters mated to the
above the average egg production of the dams in each pen is compared with the average egg production of the daughters of the dams whose egg production was below the average egg production of the dams in each pen. This manner of treating the data eliminates the influence of the male. The data in Table 4 show that there is
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Sire
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POULTRY
no significant difference between the average egg production of the daughters whose dams' production was above the dams' average egg production in each pen and the average egg production of the daughters whose dams' production was below the dams' average egg production in each pen. Apparently, therefore, in this group of dams selected on the basis of having laid a minimum of 225 eggs each during the
Data of daugh- Data of daughters and their ters and their dams whose dams whose egg producegg production was above tion was below the average the average egg producegg production of the tion of the dams in each dams in each pen pen Number of dams
59
76
Dams' average egg production 253.34 + 0.84 234.91 + 0.53 Standard deviation of dams' egg production
9.54
6.56
Number of daughters
321
472
Daughters' average egg production 202.14+1.98 199.09± 1.73 Standard deviation of daughters' egg production
37.37
38.98
first laying year, the number of eggs laid by a given dam is not a criterion of her breeding potentiality. The correlation between the egg production of the dams and the egg production of the daughters was found to be 0.17 ± 0.06, which is not significant. Since it has been suggested that a dam whose full-sisters had a high average egg production is likely to be a better breeder than a dam whose full-sisters had a lower
average egg production, the data have been analyzed with the object of testing the validity of this suggestion. In Table 5 the average egg production of the daughters of each dam whose full-sisters' average egg production (including that of the dam) was above the average egg production of the full-sisters of all dams in each pen is compared with the average egg production of the daughters of each dam whose fullsisters' average egg production (including that of the dam) was below the average egg production of the full-sisters of all dams in each pen. The records of dams that were purchased and concerning which the records of egg production of their sisters were not available have been omitted from the data given in Table 5. There were 59 dams which had 331 full-sisters whose average egg production was above the average of the full-sisters of all dams in each pen and there were 62 dams which had 389 full-sisters whose average egg production was below the average of the full-sisters of all dams in each pen. The 59 dams whose full-sisters were above the average produced 354 daughters and the 62 dams whose full-sisters were below the average produced 317 daughters. The data in Table 5 show that there is no significant difference between the average egg production of the daughters of dams whose full-sisters, including the dam herself, were above the full-sisters' average egg production in each pen and the average egg production of the daughters of dams whose full-sisters, including the dam herself, were below the full-sisters' average egg production in each pen. The correlation between the average egg production of the 121 groups of full-sisters of the dams and the average egg production of the 121 groups of daughters of the dams was found to be 0.05 ± 0.06, which is not
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TABLE 4.—-Average egg production of daughters of dams whose egg production was above and below, respectively, the mean egg production of the dams in each pen
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JANUARY,
1934.
VOL.
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significant. It is clearly apparent, therefore, that in the case of the flock of 121 dams which were selected on the basis of having laid a minimum of 225 eggs each during their first laying year, the average egg production of the full-sisters of the dam, including the dam herself, is not a criterion of the breeding potentiality of the dam.
Data of daugh- Data of daughters and full- ters and fullsisters of their sisters of their dams whose dams whose average egg average egg production was production was above the aver- below the average egg pro- age egg production of the duction of the full-sisters of full-sisters of all dams in all dams in each pen each pen Number of full-sister groups
59
62
Full-sisters' average egg production 240.59+1.17 217.81 + 1.62 Standard deviation of full-sister groups' averages
13.24
18.74
Number of daughters
354
317
Daughters' average 200.23 + 1.94 202.14+1.94 egg production Standard deviation of daughter groups' averages
21.90
22.40
Since it has been shown that in the case of the dams under discussion the dam's record of egg production is not a criterion of her breeding potentiality, it is obvious that any differences that may exist in the s egg production of the daughters of different sires must be due to differences in the breeding potentialities of the sires. It has already been pointed out in connection with the results given in Table 1 that consider-
able differences exist in the average egg production of the daughters of some of the different sires. For instance, although the average egg production of the daughters of sire No. 253 and of sire No. 254 is exactly the same, the average egg production of the daughters of sires Nos. 3, 248, and 252 differ to a marked degree. The significance of these differences is shown in Table 6. Since the difference between the average production of the daughters of each pair of sires is shown to be quite significant, the difference in each case being more than three times its probable error, it is obvious that sires No. 3, 248, and 252 differ in respect to their breeding potentialities. The results secured show that sire No. 3 is superior to sire No. 252, who in turn is superior to sire No. 248. In the selection of males and females for future breeding purposes from among the progeny of the three males, preference would naturally be given to the sons and daughters of sire No. 3. At the same time, it should be borne in mind that although the average egg production of all of the progeny of one sire may be significantly greater than the average egg production of all of the progeny of another sire, the progeny of a given dam mated to the superior sire may give a lower average egg production than the progeny of a given dam mated to the inferior sire. Sire No. 3 has been shown to be superior in breeding potentialities to sire No. 252; but the six daughters of sire No. 3 and dam No. 3767 laid an average of 219 eggs each whereas the five daughters of sire No. 252 and dam No. 4135 laid an average of 221 eggs each. Sire No. 252 has been shown to be superior to sire No. 248 in breeding potentialities but the five daughters of sire No. 252 and dam No. 3972 laid an average of 181 eggs each whereas the four daughters of sire No. 248 and dam
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TABLE 5.—Average egg production of daughters of dams whose full-sisters' average egg production, including that of the dam, was above and below, respectively, the average egg production of the full-sisters of all dams in each pen
49
5C
POULTRY TABLE 6.-
SCIENCE
•cance of the differences existing between the average egg production of daughters of three different sires
Sire No.
Daughters' average egg production
Sire No.
Daughters' average egg production
3 3 252
228.73 + 3.52 228.73 + 3.52 200.33 + 3.70
248 252 248
172.84 + 4.17 200.33 + 3.70 172.84 + 4.17
55.89 + 5.45 28.40 + 5.10 27.49 + 5.57
demonstrate that when a given mating produces good progeny the same mating might well be made in succeeding years. CONCLUSIONS In a flock of 793 Single Comb White Leghorn daughters representing the progeny of 19 selected sires and 135 selected dams, it was found that in some cases the average egg production of the daughters of different sires differed significantly, whereas between other sires there was no significant difference. It was also found that a given sire mated to a given dam may produce good progeny, whereas the same sire mated to another dam may produce poor progeny. Also, a given dam mated to a given sire may produce good progeny, but when mated to another sire may produce poor progeny. Full-sisters mated to the same sire frequently produced diverse results. The dam's record of egg production could
TABLE 7.—A verage egg production of each group of daughters produced by dams each mated to the same male two years in succession No. of daughters
Daughters' average production
1926 1927
5 6
249 248
246
1926 1927
4 6
278 240
2502
234
1926 1927
4 7
260 246
2545
218
1926 1927
4 4
248 252
Her production
Sire
Dam
41
2068
230
41
2418
41 41
Year
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No. 3845 laid an average of 202 eggs each. Further data on the breeding potentialities of the sons and daughters of different sires will be discussed in a subsequent paper. A good demonstration of the value of progeny testing is made clear by the results secured from dams each of which was mated to the same male two years in succession. Sire No. 41 was mated to four different dams in 1926 and again in 1927, the number of daughters and their average egg production being given in Table 7. The average egg production of the four dams is 232 eggs and in 1926 the average egg production of the seventeen daughters is 258 eggs whereas in 1927 the average egg production of the twenty-three daughters is 246. The difference between the average egg production of the two years is not significant, according to the Fisher method of determination for small numbers, the value of p being 0.41. The results secured in the case of these four dams
Difference
JANUARY,
1934.
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No. 1
not be used as a criterion of the dam's breeding potentiality. The record of egg production of the sire's dam could not be used as a criterion of the sire's breeding potentiality. The average egg production of a group
51
of full-sisters could not be used as a cri terion of the breeding potentiality of any of the full-sisters. The significance of progeny testing in breeding for egg production is determined by the results secured from a given mating.
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T
marked degree a standard-bred defect. A first-year record constitutes the number of eggs laid by a bird in 365 days from the date of laying the first egg. During the three years there were 1,033 birds placed in the laying houses. The only records omitted were those of birds that died, mortality amounting to 13.26 percent. The 896 daughters that completed their first year of laying averaged 192.85 eggs each. The average egg production per bird during each of three years was practically the same, viz.: 192.17, 193.50, and 192.84. The environmental conditions under which the daughters were kept during the three years were as nearly identical as it was possible to maintain. The hatching season each year occurred from March 17 to the last week in April, inclusive. Housing conditions were identical, the rations fed and the methods of feeding were the same, and the general methods of management were the same. During the winter months artificial lights were used in the morning. The breeding stock used each year consisted of males from dams that laid 225 or more eggs each and females that laid 225 or more eggs each in their first year of laying, provided, in addition, that the male and female in each case had a number of sisters with a relatively high average egg production. In other words, the selection of the breeding stock was confined to the progeny of the sires and dams that gave the best results in the previous year's breeding work. Other things than the number of eggs laid were also considered in the selection of the
144]
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 10, 2015
HE most effective way of breeding to improve egg production is to select the breeding stock from among the progeny of sires and dams that have proved to be good breeders. Such a method of breeding constitutes what is known as progeny testing. Although progeny testing is practiced by a few of the most progressive poultry breeders in various countries, the great majority of breeders frequently base the selection of their breeding stock almost entirely on the records of egg production of the females. In the latter case a hen with a 280-egg record is claimed to be a much better breeder than a hen with a 220-egg record. Also, a male, the son of a 300-egg dam, is often claimed to be a much more valuable breeder than a male, the son of a 230-egg dam. That such is not necessarily the case is clearly borne out by the data presented here. Data are presented based on the results secured in breeding Single Comb White Leghorns by the progeny-test method at the United States Animal Husbandry Experiment Farm, Beltsville, Maryland. The results include the first-year egg records of daughters during the laying years 19281929, 1929-1930, and 1930-1931. All of the daughters that each dam produced each year were placed in the laying house, except (1) those physically unfit, (2) families of fullsisters of less than five (unless the dam had previously been determined to have produced superior progeny), and (3) a few cases in which all of the daughters of a given dam were discarded because the majority of her sons and daughters possessed to a
JANUARY,
1934.
VOL.
XIII, No. 1
breeding stock used each year. The size of egg laid by each female and by her fullsisters was also taken into consideration. In some cases entire families with high records were rejected because a majority of the fullsisters laid small eggs. Also, if a dam with good egg size produced daughters the majority of which laid small eggs, none of the daughters were used as breeders and the dam herself was rejected from the breeding pen. Males for breeding purposes were selected from families of full-sisters which laid
45
with the results secured in matings that produced at least three full-sisters per family. The average egg production per daughter for all daughters produced by 19 different sires is given in Table 1 together with the number of dams mated to each sire and their average egg production. There were 135 dams used and they produced 785 daughters. The data in Table 1 show that the daughters of sire No. 3 had the highest average egg production per daughter, 229, while the daughters of sire No. 50 had the lowest
Year
Sire No.
No. of dams
1928 1928 1928 1928 1928 1929 1929 1929 1929 1929 1929 1929 1930 1930 1930 1930 1930 1930 1930
3 50 91 100
7 5 8 8 8 4 6 6 13 8 10 6 8 7 10 6 5 4 6
10106
232 235 248 249 250 252 253 254 256 259 260 261 263 264
eggs of good size. The hatchability of each dam's eggs was also taken into consideration in the selection of pullets to place in the laying house and in the selection of sons and daughters for future breeding purposes. A dam having less than 75 percent hatchability of fertile eggs was regarded as a poor breeder. Then again, due consideration has been given to standard-bred qualities in the selection of breeders from among the progeny produced each year. In order to determine the significance of progeny testing in breeding for egg production the records treated in this article deal
Dams' average No. of daughters production
248 228 254 248 239 239 234 247 243 243 247 242 237 237 243 241 246 239 242
45 49 46 59 46 15 34 42 71 37 48 31 51 27 69 38 25 19 3i
Daughters' average production
229 168 199 193 179 183 184 173 206 227 200 179 179 204 185 199 179 199 206
average egg production per daughter, 168. Judging by the average egg production of the 19 different groups of daughters, it is apparent that either the sires or the dams or both sires and dams differed considerably in their breeding potentialities. Six sires, Nos. 3, 249, 250, 252, 256, and 264, produced daughters whose average egg production was over 200 eggs per daughter. Four sires, Nos. 91, 100, 260, and 263 produced daughters whose average egg production was between 190 and 200 eggs per daughter. Three sires, Nos. 232, 235, and 259 produced daughters whose average egg produc-
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 10, 2015
TABLE 1.—Average egg production of daughters produced by 19 different sires, each mated to different groups of dams
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tion was between 180 and' 190 eggs per daughter. Five sires, Nos. 10106, 248, 253, 254, and 261 produced daughters whose average egg production was between 170 and 180 eggs per daughter. One sire, No. 50, produced daughters whose average egg production was less than 170 eggs per daughter. The fact that a dam's first-year record of egg production is not in itself a criterion of her breeding potentialities but that the kind of progeny she produces is determined large-
dam No. 3466 produced good progeny when mated to sires Nos. 50 and 249. Dam No. 3350 mated to sires Nos. 100 and 248 produced equally good progeny but dam No. 3472 produced much better progeny when mated to sire No. 100 than when mated to sire No. 248. Dam No. 3728 produced much better progeny when mated to male No. 91 than when mated to male No. 248 whereas dam No. 3845 produced much better progeny when mated to sire No. 248 than when mated to sire No. 91. The data in Table 2
Her production
Year
Sire
No. of daughters
Daughters' average production
2786
257
1927 1928 1929
46 50 249
5 5 4
217 159 228
3466
247
1928 1929
50 249
8 4
212 210
3350
246
1928 1929
100 248
9 5
200 198
3472
235
1928 1929
100 248
7 7
212 172
3728
258
1928 1929
91 248
5 3
213 167
3845
262
1928 1929
91 248
5 4
175 202
ly by the kind of mating involved is shown clearly by the results secured from dams which were mated to different males each year the dam was bred. In Table 2 is given the average egg production of each group of daughters produced by different dams selected at random each of which was mated to a different male each year she was bred. The data in Table 2 demonstrate that the kind of progeny produced by a given mating is determined by the particular kind of a mating it happens to be. Dam No. 2786 produced poor progeny when mated to sire No. 50 but good progeny when mated to sires Nos. 46 and 249. On the other hand,
tend to confirm the suggestion made previously that the egg production of a dam is not a criterion of her ability to produce good progeny. It follows, therefore, that in this group of selected sires the egg production of the sire's dam is apparently of little significance in determining his ability to produce good progeny; the validity of this statement is borne out by the results given in Table 2. It should be borne in mind that the two preceding sentences apply to the results secured from dams and sires selected rather rigidly on the basis of the egg production of their dams. The most important point brought out by
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 10, 2015
egg production of each group of daughters of dams mated to different males in different years
TABLE 2.—
Dam
SCIENCE
JANUARY,
1934.
VOL.
47
XIII, No. 1
the data in Table 2 is that the kind of progeny produced determines the relative value of a given mating rather than the breeding potentiality of either a given sire or dam. In other Words, progeny testing determines the breeding potentiality of a given sire when mated to a given dam and of a given dam when mated to a given sire.
same sire produced uniform results whereas other groups of full-sisters mated to the same sire produced diverse results. Does the dam's record of egg production bear a significant relationship to the mean egg production of her daughters? In Table 4 the average egg production of the daughters of the dams whose egg production was
TABLE 3.—Average egg production of daughters produced by each of the different full-sisters mated to the same sire Dam*
Dam's production
No. of daughters
Daughters' average production
91
3640 3845
251 262
8 5
214 175
3-
3428 3693 3769
261 243 245
8 12 5
239 235 245
3
3614 3767 3824
272 250 236
2 6 7
238 219 232
50
3289 3695
237 232
11 11
180 194
250
4050 4128
229 252
9 3
220 228
250
4086 4350 4451
259 231 254
4 5 5
242 244 220
249
3287 3289 3695
230 237 232
5 6 8
225 182 207
260
4700 4817
240 228
3 4
182 205
261
4641 4658
225 243
3 10
176 205
264
5009 5014
225 247
4 5
206 231
* The pairs and trios of dams mated to each male represent full-sisters.
The fact that full-sisters mated to the same sire do not necessarily produce similar results is clearly demonstrated by the results given in Table 3. The results given in Table 3 show that from the standpoint of the average egg production of the daughters of each dam certain groups of full-sisters mated to the
above the average egg production of the dams in each pen is compared with the average egg production of the daughters of the dams whose egg production was below the average egg production of the dams in each pen. This manner of treating the data eliminates the influence of the male. The data in Table 4 show that there is
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 10, 2015
Sire
48
POULTRY
no significant difference between the average egg production of the daughters whose dams' production was above the dams' average egg production in each pen and the average egg production of the daughters whose dams' production was below the dams' average egg production in each pen. Apparently, therefore, in this group of dams selected on the basis of having laid a minimum of 225 eggs each during the
Data of daugh- Data of daughters and their ters and their dams whose dams whose egg producegg production was above tion was below the average the average egg producegg production of the tion of the dams in each dams in each pen pen Number of dams
59
76
Dams' average egg production 253.34 + 0.84 234.91 + 0.53 Standard deviation of dams' egg production
9.54
6.56
Number of daughters
321
472
Daughters' average egg production 202.14+1.98 199.09± 1.73 Standard deviation of daughters' egg production
37.37
38.98
first laying year, the number of eggs laid by a given dam is not a criterion of her breeding potentiality. The correlation between the egg production of the dams and the egg production of the daughters was found to be 0.17 ± 0.06, which is not significant. Since it has been suggested that a dam whose full-sisters had a high average egg production is likely to be a better breeder than a dam whose full-sisters had a lower
average egg production, the data have been analyzed with the object of testing the validity of this suggestion. In Table 5 the average egg production of the daughters of each dam whose full-sisters' average egg production (including that of the dam) was above the average egg production of the full-sisters of all dams in each pen is compared with the average egg production of the daughters of each dam whose fullsisters' average egg production (including that of the dam) was below the average egg production of the full-sisters of all dams in each pen. The records of dams that were purchased and concerning which the records of egg production of their sisters were not available have been omitted from the data given in Table 5. There were 59 dams which had 331 full-sisters whose average egg production was above the average of the full-sisters of all dams in each pen and there were 62 dams which had 389 full-sisters whose average egg production was below the average of the full-sisters of all dams in each pen. The 59 dams whose full-sisters were above the average produced 354 daughters and the 62 dams whose full-sisters were below the average produced 317 daughters. The data in Table 5 show that there is no significant difference between the average egg production of the daughters of dams whose full-sisters, including the dam herself, were above the full-sisters' average egg production in each pen and the average egg production of the daughters of dams whose full-sisters, including the dam herself, were below the full-sisters' average egg production in each pen. The correlation between the average egg production of the 121 groups of full-sisters of the dams and the average egg production of the 121 groups of daughters of the dams was found to be 0.05 ± 0.06, which is not
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TABLE 4.—-Average egg production of daughters of dams whose egg production was above and below, respectively, the mean egg production of the dams in each pen
SCIENCE
JANUARY,
1934.
VOL.
X I I I , No. 1
significant. It is clearly apparent, therefore, that in the case of the flock of 121 dams which were selected on the basis of having laid a minimum of 225 eggs each during their first laying year, the average egg production of the full-sisters of the dam, including the dam herself, is not a criterion of the breeding potentiality of the dam.
Data of daugh- Data of daughters and full- ters and fullsisters of their sisters of their dams whose dams whose average egg average egg production was production was above the aver- below the average egg pro- age egg production of the duction of the full-sisters of full-sisters of all dams in all dams in each pen each pen Number of full-sister groups
59
62
Full-sisters' average egg production 240.59+1.17 217.81 + 1.62 Standard deviation of full-sister groups' averages
13.24
18.74
Number of daughters
354
317
Daughters' average 200.23 + 1.94 202.14+1.94 egg production Standard deviation of daughter groups' averages
21.90
22.40
Since it has been shown that in the case of the dams under discussion the dam's record of egg production is not a criterion of her breeding potentiality, it is obvious that any differences that may exist in the s egg production of the daughters of different sires must be due to differences in the breeding potentialities of the sires. It has already been pointed out in connection with the results given in Table 1 that consider-
able differences exist in the average egg production of the daughters of some of the different sires. For instance, although the average egg production of the daughters of sire No. 253 and of sire No. 254 is exactly the same, the average egg production of the daughters of sires Nos. 3, 248, and 252 differ to a marked degree. The significance of these differences is shown in Table 6. Since the difference between the average production of the daughters of each pair of sires is shown to be quite significant, the difference in each case being more than three times its probable error, it is obvious that sires No. 3, 248, and 252 differ in respect to their breeding potentialities. The results secured show that sire No. 3 is superior to sire No. 252, who in turn is superior to sire No. 248. In the selection of males and females for future breeding purposes from among the progeny of the three males, preference would naturally be given to the sons and daughters of sire No. 3. At the same time, it should be borne in mind that although the average egg production of all of the progeny of one sire may be significantly greater than the average egg production of all of the progeny of another sire, the progeny of a given dam mated to the superior sire may give a lower average egg production than the progeny of a given dam mated to the inferior sire. Sire No. 3 has been shown to be superior in breeding potentialities to sire No. 252; but the six daughters of sire No. 3 and dam No. 3767 laid an average of 219 eggs each whereas the five daughters of sire No. 252 and dam No. 4135 laid an average of 221 eggs each. Sire No. 252 has been shown to be superior to sire No. 248 in breeding potentialities but the five daughters of sire No. 252 and dam No. 3972 laid an average of 181 eggs each whereas the four daughters of sire No. 248 and dam
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TABLE 5.—Average egg production of daughters of dams whose full-sisters' average egg production, including that of the dam, was above and below, respectively, the average egg production of the full-sisters of all dams in each pen
49
5C
POULTRY TABLE 6.-
SCIENCE
•cance of the differences existing between the average egg production of daughters of three different sires
Sire No.
Daughters' average egg production
Sire No.
Daughters' average egg production
3 3 252
228.73 + 3.52 228.73 + 3.52 200.33 + 3.70
248 252 248
172.84 + 4.17 200.33 + 3.70 172.84 + 4.17
55.89 + 5.45 28.40 + 5.10 27.49 + 5.57
demonstrate that when a given mating produces good progeny the same mating might well be made in succeeding years. CONCLUSIONS In a flock of 793 Single Comb White Leghorn daughters representing the progeny of 19 selected sires and 135 selected dams, it was found that in some cases the average egg production of the daughters of different sires differed significantly, whereas between other sires there was no significant difference. It was also found that a given sire mated to a given dam may produce good progeny, whereas the same sire mated to another dam may produce poor progeny. Also, a given dam mated to a given sire may produce good progeny, but when mated to another sire may produce poor progeny. Full-sisters mated to the same sire frequently produced diverse results. The dam's record of egg production could
TABLE 7.—A verage egg production of each group of daughters produced by dams each mated to the same male two years in succession No. of daughters
Daughters' average production
1926 1927
5 6
249 248
246
1926 1927
4 6
278 240
2502
234
1926 1927
4 7
260 246
2545
218
1926 1927
4 4
248 252
Her production
Sire
Dam
41
2068
230
41
2418
41 41
Year
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No. 3845 laid an average of 202 eggs each. Further data on the breeding potentialities of the sons and daughters of different sires will be discussed in a subsequent paper. A good demonstration of the value of progeny testing is made clear by the results secured from dams each of which was mated to the same male two years in succession. Sire No. 41 was mated to four different dams in 1926 and again in 1927, the number of daughters and their average egg production being given in Table 7. The average egg production of the four dams is 232 eggs and in 1926 the average egg production of the seventeen daughters is 258 eggs whereas in 1927 the average egg production of the twenty-three daughters is 246. The difference between the average egg production of the two years is not significant, according to the Fisher method of determination for small numbers, the value of p being 0.41. The results secured in the case of these four dams
Difference
JANUARY,
1934.
VOL.
XIII,
No. 1
not be used as a criterion of the dam's breeding potentiality. The record of egg production of the sire's dam could not be used as a criterion of the sire's breeding potentiality. The average egg production of a group
51
of full-sisters could not be used as a cri terion of the breeding potentiality of any of the full-sisters. The significance of progeny testing in breeding for egg production is determined by the results secured from a given mating.
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