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Sampling Egg Production of Turkeys
SAMPLING EGG PRODUCTION OF TURKEYS KARL E.
NESTOR
Department of Poultry Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691 (Received for publication April 15, 1968)
TABLE 1.—Correlation coefficients (r) between total trapnest records and records obtained with various esting methods Egg Strains
M e a t Strains Days Trapnested 1 1 1-2 1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6 1-3 3-5 1-3-5 1-3-5-7 [
N o . of Observ.
r
141 141 141 141 141 141 141 141 141 141
.901 .951 .975 .986 .902 .996 .973 .946 .947 .980
2
N o . of Observ.
r
r2
812 904 951 971 984 992 948 895 898 960
72 72 72 72 72 72 72 72 72 72
.717 .831 .934 .949 .965 .985 .905 .876 .848 .941
.515 .691 .872 .901 .931 .971 .819 .767 .718 .885
r
Days were numbered consecutively beginning with Monday.
hours each day. Correlation coefficients between egg records obtained with various partial trapnesting schemes, and total egg production were determined. These are presented in Table 1. The partial trapnesting methods employed included trapnesting for 1, 2, 3, 4, 5, or 6 consecutive days each week and trapnesting for 2, 3, or 4 alternate days. The correlations were all large and positive as was expected since the correlations were between a part and the whole. However, the correlations were consistently larger in the meat strains than in the egg strains. The squares of the correlation coefficients, which measure the variation due to regression (Snedecor, 1959), are also given in Table 1. Trapnesting meat strains two or more consecutive days per week would account for 90 percent or more of the variation of total egg records. However, egg strains would have to be trapnested four or more days each week in order to obtain similar accuracy. The means and coefficients of variation obtained with the various methods of trap-
1368
Downloaded from http://ps.oxfordjournals.org/ at University of Birmingham on April 21, 2015
Partial trapnesting, that is, trapnesting less than seven days each week, has become an established practice with chickens. Wheat and Lush (1961) found that trapnesting chickens three days per week was 96 percent as accurate as complete trapping. The primary goal of egg production in the turkey industry is reproduction and, as a result, no estimate of the accuracy of partial trapnesting turkey hens has been made. It would be valuable in experimental work where a record of egg production is desired and only a part of the eggs are required for reproduction. A problem encountered with sampling egg production of turkeys that is not present with chickens is the relatively short period of egg production which results in a smaller total number of eggs being produced by turkey hens as compared to chickens. The purpose of this experiment was to determine the feasibility of estimating total egg production of turkeys for a given period of time by various partial trapnesting schemes. Data included in this analysis were based on egg production of two groups of birds. One group consisted of 141 hens from strains exhibiting meat type characteristics while the other group consisted of 72 hens from strains exhibiting high egg production characteristics. The strains within each group had similar egg production, but the egg production of the egg strains was higher than that of the meat strains. Egg production records were collected for a fifteen week period, beginning approximately ten days after the birds began to lay. All hens were lighted 14
RESEARCH NOTES
TABLE 2.—Means and coefficients of variation obtained with various trapnesting methods Days Trapnested1
1 through 7 1 1-2
1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6
1-3 3-5
1 through 7 1 1-2
1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6
1-3 3-5
1-3-5 1-3-5-7
Mean Actual (No.)
Adjusted2 (No.)
Coeff. of Variation
(%)
141 141 141 141 141 141 141 141 141 141 141
Meat Strains 46.5 46.5 6.87 48.1 13.4 47.1 20.3 47.4 27.2 47.7 33.9 47.4 40.1 46.9 13.7 48.0 13.4 46.8 20.3 47.3 26.7 46.7
41.6 45.9 42.5 41.0 41.4 40.9 40.9 42.2 40.8 41.0 42.1
72 72 72 72 72 72 72 72 72 72 72
Egg Strains 72.8 72.8 10.5 73.7 20.9 73.2 31.4 73.3 41.8 73.2 52.5 73.5 62.7 73.3 21.1 73.8 21.2 74.3 31.8 74.0 42.0 73.5
15.6 24.1 18.8 16.1 15.9 16.2 15.7 17.6 18.5 17.9 17.2
1 Days were numbered consecutively beginning with Monday. 2 Adjusted to record for 7 days per week by multiplying actual mean by 7/n where n is the number of days trapnested.
nesting are given in Table 2. The means adjusted to seven-day egg production were consistently larger in the partial trapnested groups. The egg production on weekend days (Saturday and Sunday) was slightly reduced, which was probably responsible for the greater magnitude of the adjusted means. The lowered weekend egg production probably resulted from an increase in floor eggs due to a reduction in the amount of labor employed for weekend work. Consequently, the adjusted means of the partial trapnested groups may be closer to the real mean than the average obtained by complete trapnesting. The coefficients of variation were in-
creased in both egg and meat strains by trapnesting only one day per week (Table 2). The percentage increase was greater in the egg strains than in the meat strains. The coefficients obtained with the other partial trapnesting methods were essentially the same as that obtained by complete trapnesting in the meat strains, but were consistently increased by partial trapnesting in the egg strains. This could account for the smaller correlation coefficients observed in the egg strains (Table 1). The coefficients of variation of egg production were greater in meat strains than in egg strains. Broodiness is a problem encountered in turkeys that is not present in chickens. If a broody management system is used in which broodiness is identified by egg records, it is unlikely that trapnesting less than four days per week would be feasible particularly in strains that exhibit a large amount of broodiness such as the meat strains used in this experiment. However, if some other means is used to identify broody hens, trapnesting two days a week would be adequate for sampling egg production of low producing meat strains. Trapnesting four days a week would be required to obtain the same accuracy with high producing strains. REFERENCES Snedecor, G. W., 1959. Statistical Methods. The Iowa State College Press, Ames, Iowa. Wheat, J. D., and J. L. Lush, 1961. Accuracy of partial trapnest records. 1. Repeatability of daily egg records. Poultry Sci. 40: 399-406.
NEWS AND NOTES (Continued from page 1367) The deadline for papers to be considered for INTERNATIONAL SYMPOSIUM ON TRACE travel grants is July IS, 1969. The deadline for ELEMENT METABOLISM IN ANIMALS all other papers is September 15, 1969. The details of the amounts and the number of An International Symposium on Trace Element travel grants and the format for papers will be Metabolism in Animals will be held in Aberdeen, announced at a later time. Scotland, July 14-18, 1969, under the auspices of (Continued on page 1384)
Downloaded from http://ps.oxfordjournals.org/ at University of Birmingham on April 21, 2015
1-3-5 1-3-5-7
No. of Observ.
1369
NESTOR
Department of Poultry Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691 (Received for publication April 15, 1968)
TABLE 1.—Correlation coefficients (r) between total trapnest records and records obtained with various esting methods Egg Strains
M e a t Strains Days Trapnested 1 1 1-2 1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6 1-3 3-5 1-3-5 1-3-5-7 [
N o . of Observ.
r
141 141 141 141 141 141 141 141 141 141
.901 .951 .975 .986 .902 .996 .973 .946 .947 .980
2
N o . of Observ.
r
r2
812 904 951 971 984 992 948 895 898 960
72 72 72 72 72 72 72 72 72 72
.717 .831 .934 .949 .965 .985 .905 .876 .848 .941
.515 .691 .872 .901 .931 .971 .819 .767 .718 .885
r
Days were numbered consecutively beginning with Monday.
hours each day. Correlation coefficients between egg records obtained with various partial trapnesting schemes, and total egg production were determined. These are presented in Table 1. The partial trapnesting methods employed included trapnesting for 1, 2, 3, 4, 5, or 6 consecutive days each week and trapnesting for 2, 3, or 4 alternate days. The correlations were all large and positive as was expected since the correlations were between a part and the whole. However, the correlations were consistently larger in the meat strains than in the egg strains. The squares of the correlation coefficients, which measure the variation due to regression (Snedecor, 1959), are also given in Table 1. Trapnesting meat strains two or more consecutive days per week would account for 90 percent or more of the variation of total egg records. However, egg strains would have to be trapnested four or more days each week in order to obtain similar accuracy. The means and coefficients of variation obtained with the various methods of trap-
1368
Downloaded from http://ps.oxfordjournals.org/ at University of Birmingham on April 21, 2015
Partial trapnesting, that is, trapnesting less than seven days each week, has become an established practice with chickens. Wheat and Lush (1961) found that trapnesting chickens three days per week was 96 percent as accurate as complete trapping. The primary goal of egg production in the turkey industry is reproduction and, as a result, no estimate of the accuracy of partial trapnesting turkey hens has been made. It would be valuable in experimental work where a record of egg production is desired and only a part of the eggs are required for reproduction. A problem encountered with sampling egg production of turkeys that is not present with chickens is the relatively short period of egg production which results in a smaller total number of eggs being produced by turkey hens as compared to chickens. The purpose of this experiment was to determine the feasibility of estimating total egg production of turkeys for a given period of time by various partial trapnesting schemes. Data included in this analysis were based on egg production of two groups of birds. One group consisted of 141 hens from strains exhibiting meat type characteristics while the other group consisted of 72 hens from strains exhibiting high egg production characteristics. The strains within each group had similar egg production, but the egg production of the egg strains was higher than that of the meat strains. Egg production records were collected for a fifteen week period, beginning approximately ten days after the birds began to lay. All hens were lighted 14
RESEARCH NOTES
TABLE 2.—Means and coefficients of variation obtained with various trapnesting methods Days Trapnested1
1 through 7 1 1-2
1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6
1-3 3-5
1 through 7 1 1-2
1-2-3 1-2-3-4 1-2-3-4-5 1-2-3-4-5-6
1-3 3-5
1-3-5 1-3-5-7
Mean Actual (No.)
Adjusted2 (No.)
Coeff. of Variation
(%)
141 141 141 141 141 141 141 141 141 141 141
Meat Strains 46.5 46.5 6.87 48.1 13.4 47.1 20.3 47.4 27.2 47.7 33.9 47.4 40.1 46.9 13.7 48.0 13.4 46.8 20.3 47.3 26.7 46.7
41.6 45.9 42.5 41.0 41.4 40.9 40.9 42.2 40.8 41.0 42.1
72 72 72 72 72 72 72 72 72 72 72
Egg Strains 72.8 72.8 10.5 73.7 20.9 73.2 31.4 73.3 41.8 73.2 52.5 73.5 62.7 73.3 21.1 73.8 21.2 74.3 31.8 74.0 42.0 73.5
15.6 24.1 18.8 16.1 15.9 16.2 15.7 17.6 18.5 17.9 17.2
1 Days were numbered consecutively beginning with Monday. 2 Adjusted to record for 7 days per week by multiplying actual mean by 7/n where n is the number of days trapnested.
nesting are given in Table 2. The means adjusted to seven-day egg production were consistently larger in the partial trapnested groups. The egg production on weekend days (Saturday and Sunday) was slightly reduced, which was probably responsible for the greater magnitude of the adjusted means. The lowered weekend egg production probably resulted from an increase in floor eggs due to a reduction in the amount of labor employed for weekend work. Consequently, the adjusted means of the partial trapnested groups may be closer to the real mean than the average obtained by complete trapnesting. The coefficients of variation were in-
creased in both egg and meat strains by trapnesting only one day per week (Table 2). The percentage increase was greater in the egg strains than in the meat strains. The coefficients obtained with the other partial trapnesting methods were essentially the same as that obtained by complete trapnesting in the meat strains, but were consistently increased by partial trapnesting in the egg strains. This could account for the smaller correlation coefficients observed in the egg strains (Table 1). The coefficients of variation of egg production were greater in meat strains than in egg strains. Broodiness is a problem encountered in turkeys that is not present in chickens. If a broody management system is used in which broodiness is identified by egg records, it is unlikely that trapnesting less than four days per week would be feasible particularly in strains that exhibit a large amount of broodiness such as the meat strains used in this experiment. However, if some other means is used to identify broody hens, trapnesting two days a week would be adequate for sampling egg production of low producing meat strains. Trapnesting four days a week would be required to obtain the same accuracy with high producing strains. REFERENCES Snedecor, G. W., 1959. Statistical Methods. The Iowa State College Press, Ames, Iowa. Wheat, J. D., and J. L. Lush, 1961. Accuracy of partial trapnest records. 1. Repeatability of daily egg records. Poultry Sci. 40: 399-406.
NEWS AND NOTES (Continued from page 1367) The deadline for papers to be considered for INTERNATIONAL SYMPOSIUM ON TRACE travel grants is July IS, 1969. The deadline for ELEMENT METABOLISM IN ANIMALS all other papers is September 15, 1969. The details of the amounts and the number of An International Symposium on Trace Element travel grants and the format for papers will be Metabolism in Animals will be held in Aberdeen, announced at a later time. Scotland, July 14-18, 1969, under the auspices of (Continued on page 1384)
Downloaded from http://ps.oxfordjournals.org/ at University of Birmingham on April 21, 2015
1-3-5 1-3-5-7
No. of Observ.
1369