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Breeding for Increased Egg Production in Beltsville Small White Turkeys
POULTRY S C I E N C E May, 1954, Vol. 3 3 , N o . 3 •
Breeding for Increased Egg Production in Beltsville Small White Turkeys Animal and Poultry Husbandry Research Branch, Agricultural Research Service, United States Department of Agriculture, Beltsmlle, Maryland (Received for publication May 4, 1953)
T
HE small number of eggs and the shortness of the hatching season have contributed toward the limiting of turkeys to the November and December markets. Some years ago it was believed that there was a place for fresh turkey meat throughout the year as a substitute for large roasting chickens, which are becoming relatively fewer with each successive year. In order to produce turkey meat throughout the year, it would be necessary to increase, if possible, the number of eggs produced and to extend the length of the laying period. Lately a further incentive has-been added to improve egg production, and this is the production, throughout the year, of turkey broilers, or light roasters with a live weight iof about 4 to 12 pounds each. Therefore, any improvement in turkey egg production would be a welcome asset for the turkey industry. REVIEW OF LITERATURE
Wilson and Johnson (1946), reported a very low coefficient of heritability of + .02. They state in part that "it is possible (although we think improbable) that in these particular flocks the dams happened to be much more alike in their genetic values than would usually be the
case. Practical experiences in turkey production indicate that the true value is unlikely to be as low as +.02." Such a low coefficient would mean that possible progress in improving egg production through selection on the basis of individual egg production records would be slow. However, their coefficient was obtained by pooling several groups of data which included Bronze and Beltsville Type Whites. The separate data as given by them for the two groups of Beltsville Small Whites was 34 and 38 percent heritability which is relatively high and would indicate that more progress could be made in these groups than in the Bronze groups. The reason for the low heritability estimate when all groups were combined was the small numbers of Beltsville Small Whites that were used. Others who reported on egg production were Albright and Thompson (1933), Marsden (1936), Asmundsen (1941), and Whitson et al. (1944). MATERIALS AND METHODS
Selection for increased egg production in Beltsville Small White Turkeys was started in 1944 and continued through 1951. As nearly as possible, similar conditions of housing, feeding, and manage-
443
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
C. W. KNOX AND STANLEY J. MARSDEN
444
C. W. KNOX AND S. J. MARSDEN
Artificial lighting was used all eight years. In 1944 they were turned on starting November 1, at 4:00 a.m.; subsequent years lighting was started the first week in December. They were housed in pens 14'X14' and 6 breeding pens in a house. As broodiness is considered a detrimental factor to egg production, selection against broodiness was made simultaneously with selection for egg production. As the incidence of broodiness decreased greater selection was made against this characteristic.
one to expect but slow progress in the improvement of egg production in turkeys. The present experiment is of interest because it was continued for a period of eight years. Increases in egg production were fairly constant and relatively rapid to June 1 and for a season of 9 months egg production. These data indicate greater progress in egg production was made than expected and greater than has been reported thus far. Table 1 shows a rather rapid increase in egg production over an eight year period accomplished by selection of the parental stock on individual egg production records. Young toms were used throughout the tenure of this experiment. They were selected on their type and the egg production of their dams. In later years they had to come from high egg production dams. Most of the hens in the breeding pen were TABLE 1.—Egg production in BellsvMe Small White Turkeys Egg Production to June 1
Year
1944 1945 1946 1947 1948 1949 1950 1951
Paternal granddams
Egg prod.
w „ No. No. e g g s
AT
64.5 72.9 59.6 79.7 79.9 82.4 86.1 104.3
4— 68.8 5— 88.0 6—106.1 6— 96.3 7—102.4 6— 95.5 6—105.1 6—100.7
41—61.7 42—75.9 54—80.0 56—71.2 89—83.9 70—90.0 64—95.1 68—94.7
Dams
No.
66 71 103 112 134 90 116 105
RESULTS AND DISCUSSION OF EGG PRODUCTION
Heritability estimates of egg production in chickens from various sources indicate that selection is probably responsible for 20 to 34 percent of the total variation found in egg production. Shoffner (1946) and Lerner and Cruden (1948) found fairly high coefficients of heritability in chickens, 34 and 33 percent respectively. Even these are rather low and would lead
Progeny
No
Combined dams and paternal granddams Av. egg. prod. 65.2 82.0 93.0 83.8 93.2 92.8 100.1 97.7
Egg Production for 9 Months (January to October 1) Progeny Year
Dams
No. Egg prod.
1944 1945 1946 1947 1948 1949 1950 1951
Paternal granddams
54 65 90 98 123 60 109 99
79.6 88.0 84.8 103.2 109.4 114.4 120.2 146.2
XT No
-
No. eggs
4— 73.5 5—121.0 6—155.0 6—128.7 7—141.0 6—134.0 6—153. S 6—152.0
XT
No
No. - eggs
4 1 — 75.7 42— 97.0 54—101.6 56— 98.8 89—113.2 70—128.1 64—133.6 68—133.2
Combined dams and paternal granddams Av. egg prod. 74.6 109.0 128.3 113.8 127.1 131.0 143.6 142.6
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
ment were kept from year to year. Breeders were selected each year on the basis of observations at 24 weeks upon body weight, finish, feathering and conformation. Major emphasis was placed on the first two characteristics and egg production assumed a minor consideration. However, as egg production assumed greater importance to the industry in later years, selection of breeders for egg production became more important and was given a major place in the selection program, but was not the sole characteristic used. By far the greatest selection for egg production was based on performance tests as revealed by trap nest records. Approximately 10 percent of the hens were kept for more than one breeding season, and no males were kept beyond the first breeding season.
BREEDING FOR PRODUCTION IN TURKEYS
where practically no previous effective selection had been made. This is true for the data of Whitson el al. (1944), for four different varieties of turkeys and probably true for the turkeys reported by Asmundson (1941), for Standard Bronze turkeys from 1934 to 1938. This was also true of the turkeys reported by Albright and Thompson (1933), who obtained an average of 86 eggs per hen from December 1 to July 1 and 124 eggs for a full year. It might be true of the turkey production reported by Asmundson and Lloyd (1935), who obtained an average annual egg production of 77 eggs for all 7 years studied from 1927 to 1933 with a low production of 61 eggs in 1927 to the highest of 83 in 1931, and for the data of Mardsen (1936), who obtained an average egg production to May 31 inclusive from lighted Standard Bronze turkeys of 46 eggs in 1932 to 51 eggs in 1935 with a high of 51.4 eggs in 1934. Previous to 1944 there was practically no effort to improve egg production in this flock of Beltsville Small Whites which were progenitors of the present fiock at Beltsville, and egg production to June 1 was fairly constant, but low when compared to the high production obtained in later years. In spite of the low coefficient of heritability of egg production, .02, reported by Wilson and Johnson (1946) their data indicate a much higher estimate of heritability for the egg production of the Beltsville Small Whites, being 32 percent and 38 percent for each of the two similar stocks studied. BROODINESS
Practically no previous effort has been reported on attempts to breed turkeys for non-broodiness. As broodiness has long been considered detrimental to maximum egg production in chickens, selection for non-broodiness was begun simultaneously
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
of the current year's rearing and hence had not begun their laying period. A few hens that produced a greater number of eggs than the average were used a second year with a greater percentage of such hens being held over for another year in the later years of the experiment. As selection for egg production was based mainly on the performance of the dam and the paternal granddam, it would be of interest to note the trend and effectiveness of such selections as measured by average egg production of each year's group of dams and paternal granddams and progeny. Hence, the average egg production of the dams and paternal granddams of the selected sires for each year is given in Table 1. It will be noted in this table that there is a fairly consistent increase in the dam's and paternal granddam's egg production to June 1 and to October 1 for eight years. The average egg production of the paternal granddams of the toms selected each year was almost as great in any year as the greatest average egg production of the dams which was 133.2 in 1951 and 133.6 eggs.in 1950. Each year hen breeders represented more than 50 percent of the unselected female population. The selection practiced seemed to be sufficient for improvement in the egg producing capabilities of the unselected progeny. The level of production each year as given in Table 1 indicates the success of such selection. The average production for the selected paternal granddams increased very rapidly from 1944 to 1946 inclusive, increasing from an average of 73.5 to 155 eggs for 9 months production, and from 69 to 106 eggs to June 1. The egg production of the dams also indicates that egg production can be improved relatively rapidly by selection when properly done. It may be that previous studies were made on flocks
445
446
C. W. KNOX AND S. J. MARSDEN
The data in Table 2 indicate, at least, two things. First, that egg production to June 1, or for a 10 months period, can be increased by proper selection irrespective of broodiness and secondly, that broodiness interferes to some extent with egg production. The number of times a bird
TABLE 2.—Broodiness and production in Bdtsville Small Type White turkeys Broodiness and Egg Production to June 1 B. Year
1944 1945 1946 1947 1948 1949 1950 1951
Percent nonbroody 18 15 16 18 43 31 49 75
Totals and Aver.*
B2
Bi
No.
Aver. no. eggs
12 11 16 20 56 28 57 79
78 87 64 89 81 94 93 105
279
86.4
No.
Aver. no. eggs
9 9 23 24 26 24 27 13
50 70 64 85 86 86 83 105
155
78.6
B,
No.
Aver. no. eggs
14 11 27 20 20 16 16 3 127
B,
No.
Aver. no. eggs
No.
Aver. no. eggs
51 70 55 74 72 70 74 62
9 9 22 21 17 14 5 0
60 67 50 70 70 69 63
8 IS 10 21 11 7 6 7
60 70 50 69 66 65 60 77
66.0
97
85
64.5
— 64.1
Bs
B.
Aver. N o . no. eggs
Aver. N o . no. eggs
9 9 2 6 4 1 5 3 39
71 73 62 70 67 83 65 76
3 3 3 0 0 0 0 0
70.1
9
B,
60 69 49
— — — — — 66.0
No.
Aver. no. eggs
2 4 0 0 0 0
66 68
— — — — — —
{)
0 6
67.0
Broodiness and Egg Production for 9 Months (January to October) Bo
Percent Year
1944 1945 1946 1947 1948 1949 1950 1951
nonbroody 19 14 10 16 39 40 49 75
Totals and Aver.*
* Unweighted.
No.
Aver. no. eggs
10 9 9 16 48 24 53 74
114 112 118 133 125 141 141 155
243
129.9
Bi
B«
No.
Aver. no. eggs
8 6 21 21 26 20 26 12
57 87 97 116 118 132 116 138
140
107.6
B,
No.
Aver. no. eggs
8 10 24 18 17 8 14 3
64 78 80 94 104 106 105 86
102
89.6
B.
No.
Aver. no. eggs
No.
Aver. no. eggs
8 9 22 18 17 5 5 0
58 77 72 97 92 103 83
7 15 9 19 11 2 6 7
77 86 69 89 91 98 82 93
76
85.3
84
— 83.1
B,
B.
Aver. N o . no. eggs
Aver. N o . no. eggs
9 9 2 6 4 1 5 3 39
88 88 77 87 93 106 92 92 90.4
3 3 3 0 0 0 0 0 9
B,
72 94 69
— — — — — 78.3
No. 1 4 0 0 0 0 0 0 5
Aver. no. eggs 81 98
— — — — — — 89.5
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
Although these periods are considered for convenience as broody periods it may be that if the broody birds were not molested they probably would be broody for a much longer period of time and not have many such periods. It may be assumed, however, that the turkeys with the greater number of broody periods, if left alone, would have natural broody periods of greater length than those turkeys with few "artificial" periods. There was approximately 18 days of non-production during the broody periods, each being counted from the day of cessation of egg production to subsequent onset of production.
with selection for egg production. Turkeys broody once or twice in their first laying year that had good egg production records were used as breeders as well as non-broody birds. The number of these used, however, were very much in the minority, especially in the last three years. As soon as a turkey stayed in the trap nest and showed signs of broodiness she was removed and placed in a wire coop with a wire bottom, fed and watered reg'ularly a-nd after four days was again jSlaced in the pen. If she remained out of the nest that day and night, she was considered as being over broodiness. Each time such treatment was necessary, was considered a broody period and some turkeys had as many as 7 of these in the nine months period. Only rarely was it necessary to repeat this treatment because the bird still showed signs of broodiness.
447
ERRATUM
SUMMARY
Egg production of Beltsville Small White turkeys to June 1 and for 9 months (October 1) was materially increased by simple selection methods based on individual trap nest records.
The same methods of selection increased non-broodiness in turkeys. Average egg production to June 1 was increased from 64.5 eggs in 1944 to 104.3 eggs in 1951 and for 9 months (average egg production to October 1) was increased from 79.6 to 146.2 eggs. Non-broodiness was increased from 19 and 14 percent during 1944 and 1945 respectively to 75 percent non-broody in 1951. The number of times needed to "breakup" maximum broody birds decreased from 7 times to 5 times during the same period and there was a lesser percentage of broodiness in most of the broody groups. REFERENCES Albright, W. P., and R. B. Thompson, 1933. Securing early turkeys by stimulated egg production. Poultry Sci. 12:124-128. Asrmmdson, V. S., and W. E. Lloyd, 1935. Effect of age on reproduction of the turkey hen. Poultry Sci. 14: 259-266. Asmundson, V. S., 1941. Differences in sexual maturity and egg production of turkeys. Poultry Sci. 20: 51-56. Lerner, I. M., and D. M. Cruden, 1948. The heritability of accumulative monthly and annual egg production. Poultry Sci. 27: 67-78. Marsden, S. J., 1936. A study of egg production in Bronze turkeys. Poultry Sci. 15: 439-445. Shoffner, R. N., 1946. The heritability of egg production. Poultry Sci. 25: 412. Whitson, D., S. J. Marsden and H. W. Titus, 1944. Comparison of the performance of four varieties of turkeys during the breeding season. Poultry Sci. 23:314-320. Wilson, W. O., and L. E. Johnson, 1946. The inheritance of egg production and hatchability in turkeys. Poultry Sci. 25: 278-284.
ERRATUM Table 4, page 195 of the January issue, contains an error. In the line entitled % Hatchability, the fig-
ure for Lot No. 1 should be 69.1 instead of 49.1 as appeared in the Table.
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
is broody, up to three times, has a cumulative detrimental effect upon egg production to June 1 and October 1. However, practically no greater detrimental effect was noted for birds having four or more broody periods. In eight years, as shown in Table 2, there was an increase in the egg production to June 1 of the non-broody birds from 78 eggs in 1944 to 105 eggs in 1951, and 114 to 155 for 9 months production. A similar increase was true of the birds that went broody once, and to a much lesser extent for the turkeys that were broody twice. For the period of June 1 the production increased from 50 eggs in 1944 to 105 in 1951 for the turkeys broody once (Bi) and from 51 to 62 eggs for the turkeys broody twice (B2). Although the trend of egg production was upward in turkeys broody three or more times, it was not consistent nor was the difference significant. However, the data do show that where broody turkeys are managed properly, more than three broody periods did not further decrease final production to June 1, or for the nine months period. It may be assumed, therefore, that the broody turkeys, once their broodiness was broken up, produced eggs at a greater rate than similar non-broody birds.
Breeding for Increased Egg Production in Beltsville Small White Turkeys Animal and Poultry Husbandry Research Branch, Agricultural Research Service, United States Department of Agriculture, Beltsmlle, Maryland (Received for publication May 4, 1953)
T
HE small number of eggs and the shortness of the hatching season have contributed toward the limiting of turkeys to the November and December markets. Some years ago it was believed that there was a place for fresh turkey meat throughout the year as a substitute for large roasting chickens, which are becoming relatively fewer with each successive year. In order to produce turkey meat throughout the year, it would be necessary to increase, if possible, the number of eggs produced and to extend the length of the laying period. Lately a further incentive has-been added to improve egg production, and this is the production, throughout the year, of turkey broilers, or light roasters with a live weight iof about 4 to 12 pounds each. Therefore, any improvement in turkey egg production would be a welcome asset for the turkey industry. REVIEW OF LITERATURE
Wilson and Johnson (1946), reported a very low coefficient of heritability of + .02. They state in part that "it is possible (although we think improbable) that in these particular flocks the dams happened to be much more alike in their genetic values than would usually be the
case. Practical experiences in turkey production indicate that the true value is unlikely to be as low as +.02." Such a low coefficient would mean that possible progress in improving egg production through selection on the basis of individual egg production records would be slow. However, their coefficient was obtained by pooling several groups of data which included Bronze and Beltsville Type Whites. The separate data as given by them for the two groups of Beltsville Small Whites was 34 and 38 percent heritability which is relatively high and would indicate that more progress could be made in these groups than in the Bronze groups. The reason for the low heritability estimate when all groups were combined was the small numbers of Beltsville Small Whites that were used. Others who reported on egg production were Albright and Thompson (1933), Marsden (1936), Asmundsen (1941), and Whitson et al. (1944). MATERIALS AND METHODS
Selection for increased egg production in Beltsville Small White Turkeys was started in 1944 and continued through 1951. As nearly as possible, similar conditions of housing, feeding, and manage-
443
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
C. W. KNOX AND STANLEY J. MARSDEN
444
C. W. KNOX AND S. J. MARSDEN
Artificial lighting was used all eight years. In 1944 they were turned on starting November 1, at 4:00 a.m.; subsequent years lighting was started the first week in December. They were housed in pens 14'X14' and 6 breeding pens in a house. As broodiness is considered a detrimental factor to egg production, selection against broodiness was made simultaneously with selection for egg production. As the incidence of broodiness decreased greater selection was made against this characteristic.
one to expect but slow progress in the improvement of egg production in turkeys. The present experiment is of interest because it was continued for a period of eight years. Increases in egg production were fairly constant and relatively rapid to June 1 and for a season of 9 months egg production. These data indicate greater progress in egg production was made than expected and greater than has been reported thus far. Table 1 shows a rather rapid increase in egg production over an eight year period accomplished by selection of the parental stock on individual egg production records. Young toms were used throughout the tenure of this experiment. They were selected on their type and the egg production of their dams. In later years they had to come from high egg production dams. Most of the hens in the breeding pen were TABLE 1.—Egg production in BellsvMe Small White Turkeys Egg Production to June 1
Year
1944 1945 1946 1947 1948 1949 1950 1951
Paternal granddams
Egg prod.
w „ No. No. e g g s
AT
64.5 72.9 59.6 79.7 79.9 82.4 86.1 104.3
4— 68.8 5— 88.0 6—106.1 6— 96.3 7—102.4 6— 95.5 6—105.1 6—100.7
41—61.7 42—75.9 54—80.0 56—71.2 89—83.9 70—90.0 64—95.1 68—94.7
Dams
No.
66 71 103 112 134 90 116 105
RESULTS AND DISCUSSION OF EGG PRODUCTION
Heritability estimates of egg production in chickens from various sources indicate that selection is probably responsible for 20 to 34 percent of the total variation found in egg production. Shoffner (1946) and Lerner and Cruden (1948) found fairly high coefficients of heritability in chickens, 34 and 33 percent respectively. Even these are rather low and would lead
Progeny
No
Combined dams and paternal granddams Av. egg. prod. 65.2 82.0 93.0 83.8 93.2 92.8 100.1 97.7
Egg Production for 9 Months (January to October 1) Progeny Year
Dams
No. Egg prod.
1944 1945 1946 1947 1948 1949 1950 1951
Paternal granddams
54 65 90 98 123 60 109 99
79.6 88.0 84.8 103.2 109.4 114.4 120.2 146.2
XT No
-
No. eggs
4— 73.5 5—121.0 6—155.0 6—128.7 7—141.0 6—134.0 6—153. S 6—152.0
XT
No
No. - eggs
4 1 — 75.7 42— 97.0 54—101.6 56— 98.8 89—113.2 70—128.1 64—133.6 68—133.2
Combined dams and paternal granddams Av. egg prod. 74.6 109.0 128.3 113.8 127.1 131.0 143.6 142.6
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
ment were kept from year to year. Breeders were selected each year on the basis of observations at 24 weeks upon body weight, finish, feathering and conformation. Major emphasis was placed on the first two characteristics and egg production assumed a minor consideration. However, as egg production assumed greater importance to the industry in later years, selection of breeders for egg production became more important and was given a major place in the selection program, but was not the sole characteristic used. By far the greatest selection for egg production was based on performance tests as revealed by trap nest records. Approximately 10 percent of the hens were kept for more than one breeding season, and no males were kept beyond the first breeding season.
BREEDING FOR PRODUCTION IN TURKEYS
where practically no previous effective selection had been made. This is true for the data of Whitson el al. (1944), for four different varieties of turkeys and probably true for the turkeys reported by Asmundson (1941), for Standard Bronze turkeys from 1934 to 1938. This was also true of the turkeys reported by Albright and Thompson (1933), who obtained an average of 86 eggs per hen from December 1 to July 1 and 124 eggs for a full year. It might be true of the turkey production reported by Asmundson and Lloyd (1935), who obtained an average annual egg production of 77 eggs for all 7 years studied from 1927 to 1933 with a low production of 61 eggs in 1927 to the highest of 83 in 1931, and for the data of Mardsen (1936), who obtained an average egg production to May 31 inclusive from lighted Standard Bronze turkeys of 46 eggs in 1932 to 51 eggs in 1935 with a high of 51.4 eggs in 1934. Previous to 1944 there was practically no effort to improve egg production in this flock of Beltsville Small Whites which were progenitors of the present fiock at Beltsville, and egg production to June 1 was fairly constant, but low when compared to the high production obtained in later years. In spite of the low coefficient of heritability of egg production, .02, reported by Wilson and Johnson (1946) their data indicate a much higher estimate of heritability for the egg production of the Beltsville Small Whites, being 32 percent and 38 percent for each of the two similar stocks studied. BROODINESS
Practically no previous effort has been reported on attempts to breed turkeys for non-broodiness. As broodiness has long been considered detrimental to maximum egg production in chickens, selection for non-broodiness was begun simultaneously
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
of the current year's rearing and hence had not begun their laying period. A few hens that produced a greater number of eggs than the average were used a second year with a greater percentage of such hens being held over for another year in the later years of the experiment. As selection for egg production was based mainly on the performance of the dam and the paternal granddam, it would be of interest to note the trend and effectiveness of such selections as measured by average egg production of each year's group of dams and paternal granddams and progeny. Hence, the average egg production of the dams and paternal granddams of the selected sires for each year is given in Table 1. It will be noted in this table that there is a fairly consistent increase in the dam's and paternal granddam's egg production to June 1 and to October 1 for eight years. The average egg production of the paternal granddams of the toms selected each year was almost as great in any year as the greatest average egg production of the dams which was 133.2 in 1951 and 133.6 eggs.in 1950. Each year hen breeders represented more than 50 percent of the unselected female population. The selection practiced seemed to be sufficient for improvement in the egg producing capabilities of the unselected progeny. The level of production each year as given in Table 1 indicates the success of such selection. The average production for the selected paternal granddams increased very rapidly from 1944 to 1946 inclusive, increasing from an average of 73.5 to 155 eggs for 9 months production, and from 69 to 106 eggs to June 1. The egg production of the dams also indicates that egg production can be improved relatively rapidly by selection when properly done. It may be that previous studies were made on flocks
445
446
C. W. KNOX AND S. J. MARSDEN
The data in Table 2 indicate, at least, two things. First, that egg production to June 1, or for a 10 months period, can be increased by proper selection irrespective of broodiness and secondly, that broodiness interferes to some extent with egg production. The number of times a bird
TABLE 2.—Broodiness and production in Bdtsville Small Type White turkeys Broodiness and Egg Production to June 1 B. Year
1944 1945 1946 1947 1948 1949 1950 1951
Percent nonbroody 18 15 16 18 43 31 49 75
Totals and Aver.*
B2
Bi
No.
Aver. no. eggs
12 11 16 20 56 28 57 79
78 87 64 89 81 94 93 105
279
86.4
No.
Aver. no. eggs
9 9 23 24 26 24 27 13
50 70 64 85 86 86 83 105
155
78.6
B,
No.
Aver. no. eggs
14 11 27 20 20 16 16 3 127
B,
No.
Aver. no. eggs
No.
Aver. no. eggs
51 70 55 74 72 70 74 62
9 9 22 21 17 14 5 0
60 67 50 70 70 69 63
8 IS 10 21 11 7 6 7
60 70 50 69 66 65 60 77
66.0
97
85
64.5
— 64.1
Bs
B.
Aver. N o . no. eggs
Aver. N o . no. eggs
9 9 2 6 4 1 5 3 39
71 73 62 70 67 83 65 76
3 3 3 0 0 0 0 0
70.1
9
B,
60 69 49
— — — — — 66.0
No.
Aver. no. eggs
2 4 0 0 0 0
66 68
— — — — — —
{)
0 6
67.0
Broodiness and Egg Production for 9 Months (January to October) Bo
Percent Year
1944 1945 1946 1947 1948 1949 1950 1951
nonbroody 19 14 10 16 39 40 49 75
Totals and Aver.*
* Unweighted.
No.
Aver. no. eggs
10 9 9 16 48 24 53 74
114 112 118 133 125 141 141 155
243
129.9
Bi
B«
No.
Aver. no. eggs
8 6 21 21 26 20 26 12
57 87 97 116 118 132 116 138
140
107.6
B,
No.
Aver. no. eggs
8 10 24 18 17 8 14 3
64 78 80 94 104 106 105 86
102
89.6
B.
No.
Aver. no. eggs
No.
Aver. no. eggs
8 9 22 18 17 5 5 0
58 77 72 97 92 103 83
7 15 9 19 11 2 6 7
77 86 69 89 91 98 82 93
76
85.3
84
— 83.1
B,
B.
Aver. N o . no. eggs
Aver. N o . no. eggs
9 9 2 6 4 1 5 3 39
88 88 77 87 93 106 92 92 90.4
3 3 3 0 0 0 0 0 9
B,
72 94 69
— — — — — 78.3
No. 1 4 0 0 0 0 0 0 5
Aver. no. eggs 81 98
— — — — — — 89.5
Downloaded from http://ps.oxfordjournals.org/ at University of Tasmania Library on June 13, 2015
Although these periods are considered for convenience as broody periods it may be that if the broody birds were not molested they probably would be broody for a much longer period of time and not have many such periods. It may be assumed, however, that the turkeys with the greater number of broody periods, if left alone, would have natural broody periods of greater length than those turkeys with few "artificial" periods. There was approximately 18 days of non-production during the broody periods, each being counted from the day of cessation of egg production to subsequent onset of production.
with selection for egg production. Turkeys broody once or twice in their first laying year that had good egg production records were used as breeders as well as non-broody birds. The number of these used, however, were very much in the minority, especially in the last three years. As soon as a turkey stayed in the trap nest and showed signs of broodiness she was removed and placed in a wire coop with a wire bottom, fed and watered reg'ularly a-nd after four days was again jSlaced in the pen. If she remained out of the nest that day and night, she was considered as being over broodiness. Each time such treatment was necessary, was considered a broody period and some turkeys had as many as 7 of these in the nine months period. Only rarely was it necessary to repeat this treatment because the bird still showed signs of broodiness.
447
ERRATUM
SUMMARY
Egg production of Beltsville Small White turkeys to June 1 and for 9 months (October 1) was materially increased by simple selection methods based on individual trap nest records.
The same methods of selection increased non-broodiness in turkeys. Average egg production to June 1 was increased from 64.5 eggs in 1944 to 104.3 eggs in 1951 and for 9 months (average egg production to October 1) was increased from 79.6 to 146.2 eggs. Non-broodiness was increased from 19 and 14 percent during 1944 and 1945 respectively to 75 percent non-broody in 1951. The number of times needed to "breakup" maximum broody birds decreased from 7 times to 5 times during the same period and there was a lesser percentage of broodiness in most of the broody groups. REFERENCES Albright, W. P., and R. B. Thompson, 1933. Securing early turkeys by stimulated egg production. Poultry Sci. 12:124-128. Asrmmdson, V. S., and W. E. Lloyd, 1935. Effect of age on reproduction of the turkey hen. Poultry Sci. 14: 259-266. Asmundson, V. S., 1941. Differences in sexual maturity and egg production of turkeys. Poultry Sci. 20: 51-56. Lerner, I. M., and D. M. Cruden, 1948. The heritability of accumulative monthly and annual egg production. Poultry Sci. 27: 67-78. Marsden, S. J., 1936. A study of egg production in Bronze turkeys. Poultry Sci. 15: 439-445. Shoffner, R. N., 1946. The heritability of egg production. Poultry Sci. 25: 412. Whitson, D., S. J. Marsden and H. W. Titus, 1944. Comparison of the performance of four varieties of turkeys during the breeding season. Poultry Sci. 23:314-320. Wilson, W. O., and L. E. Johnson, 1946. The inheritance of egg production and hatchability in turkeys. Poultry Sci. 25: 278-284.
ERRATUM Table 4, page 195 of the January issue, contains an error. In the line entitled % Hatchability, the fig-
ure for Lot No. 1 should be 69.1 instead of 49.1 as appeared in the Table.
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is broody, up to three times, has a cumulative detrimental effect upon egg production to June 1 and October 1. However, practically no greater detrimental effect was noted for birds having four or more broody periods. In eight years, as shown in Table 2, there was an increase in the egg production to June 1 of the non-broody birds from 78 eggs in 1944 to 105 eggs in 1951, and 114 to 155 for 9 months production. A similar increase was true of the birds that went broody once, and to a much lesser extent for the turkeys that were broody twice. For the period of June 1 the production increased from 50 eggs in 1944 to 105 in 1951 for the turkeys broody once (Bi) and from 51 to 62 eggs for the turkeys broody twice (B2). Although the trend of egg production was upward in turkeys broody three or more times, it was not consistent nor was the difference significant. However, the data do show that where broody turkeys are managed properly, more than three broody periods did not further decrease final production to June 1, or for the nine months period. It may be assumed, therefore, that the broody turkeys, once their broodiness was broken up, produced eggs at a greater rate than similar non-broody birds.