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Influence of Sire on the Response to Pre-Incubation Warming of Turkey Eggs*
Influence of Sire on the Response to Pre-Incubation Warming of Turkey Eggs* F. L. CHEEMS, JR.
Department of Poultry Husbandry, University of Wisconsin, Madison (Received for publication September 25, 1959)
T
PROCEDURE
The stock used in this study was the trapnested Station flock of Broad Breasted Bronze turkeys. In 1958 there were 136 females started in 11 single male mating pens, and in 1959 there were 110 females started in 10 single male mating pens. The eggs were all marked in the usual manner with the hen number, pen number, and date laid. Eggs were held in an egg holding room at about 55°F. at the research farm for 7 days and then they were delivered to the hatchery for treatment. Before being treated, the eggs were sorted by hens within pens and by date within hens. Then the eggs were assigned to the treatments, with every other egg from a hen being assigned to the same treatment in 1958 and every third egg to the same treatment in 1959. The following treatments were * Published with the approval of the Director of the Wisconsin Agricultural Experiment Station, College of Agriculture, Madison, Wisconsin.
tested: 1) in 1958 the eggs were heated for 1 hour at 100°F., and 2) in 1959 the eggs were heated for 1 and 5 hours at 100°F. Once the eggs had been assigned to the treatments they were reshuffled so that all of the eggs on one treatment were placed together. Then, those to be pre-heated were placed in pre-warmed incubators while the control eggs were maintained at room temperature until the treatment was finished. After completion of the treatment the eggs were immediately placed in an egg cooler which was maintained at 50°F. Settings were made every two weeks and therefore the eggs that were 9 to 15 days old when set where in the cooler for one week while the eggs which were 2 to 8 days old when set were in the cooler overnight. The youngest eggs set were 2 days of age instead of 1 day because of time needed to complete the procedure just described. All eggs were candled at 7 days of incubation and those which were said to be infertile were broken out to check for early dead embryos. The eggs were again candled at 24 days and then placed in pedigree hatching trays. When the hatch was taken off, the usual procedure was followed when pedigreeing. RESULTS AND DISCUSSION
A total of 3,757 fertile eggs was involved in the 1958 experiment and 2,550 fertile eggs in the 1959 experiment. The breakdown of the number of fertile eggs by hatches and treatments for each year is shown in Table 1. The smaller number of fertile eggs in 1959 can be accounted for
813
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
HE apparent increase in hatchability of turkey eggs when submitted to a pre-incubation period of warming as reported by Kosin (1956) and of chicken eggs as shown by Jackson (1912) and Becker and Bearse (1958) raises the question as to whether there is a genetic effect on this response. If such an effect exists, it may be a clue as to why certain sire families exhibit higher hatchability than do other families. This study was designed so as to determine if there are sire family differences in the response to pre-incubation warming.
814
F. L. CHERMS, JR.
TABLE 1.—The number of fertile eggs by hatches, treatments, and years in the pre-incubation warming study 1958 lhr. warming
Control
Stored
Stored
Date hatched
1/30 3/13 3/27 4/10
2-8 days
9-15 days
2-8 days
9-15 days
272 253 234 221
276 255 196 197
264 250 238 202
266 243 191 199
980
924
954
899
5 hr. warming Date hatched
1/15 2/12 2/26 4/23
Control
hr. warming
Stored
Stored
Stored
2-8 days
9-15 days
2-8 days
9-15 days
2-8 days
9-15 days
109 129 126 61
97 114 141 65
106 127 126 61
95 126 138 67
107 125 138 68
91 125 136 72
425
417
420
426
438
424
by the fewer number of hens and a decrease in fertility of about 10% in 1959. When the data for all dam and sire families are combined (Table 2) there does not appear to be any improvement in hatchability of the eggs that were 2 to 8 days old when set. However, treated eggs that were 9 to 15 days old when set hatched 7% better than the control eggs in 1958 and 5% better in 1959. Warming of eggs for 5 hours gave about the same response as did 1 hour warming. A separate analysis of variance was calculated for the data obtained in both years to test if the difference between treatments
was significant and also to determine if there was a significant sire effect on the response to warming (Tables 3 and 4). Both sets of calculations were made on the averages of the dams within each sire. Data were available by daughters within dams and also by hatches but it was felt that the information wanted could be obtained by the analysis reported here. In the analysis of the 1958 data it will be noted that there are 3 degrees of freedom for treatments. This includes the following categories: 1) 2 to 8 day pre-heated eggs, 2) 2 to 8 day controls, 3) 9 to 15 day pre-heated eggs, and 4) 9 to 15 day controls. In 1959 there
TABLE 2.—General hatchability response to pre-incubation warming of turkey eggs Stored 2-8 days Year 1958 1959
Stored 9-15 days
5hr. warming
1 hr. warming
Control
5hr. warming
lhr. warming
Control
65
67 64
66 64
59
58 59
51 54
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
1959
PRE-INCUBATION WARMING OF EGGS
815
Kosin (1956) discusses the possibility that eggs with a high hatchability potential probably have attained the optimum state Source of variation d M.S. F of embryological development. It seems Between dams 16 449 .968 Between sires 5 415 .894 logical to assume then that eggs from hens D a m s within sires 464 11 of normally high hatchability might be ad3 1,245 2 5 . 4 0 8 " Between treatments 1 3,332 68.000** Storage versely affected by the pre-heating treat1 313 6..189* Preheat vs. no preheat 1 89 1.816 Storage X (preheat vs. no preheat) ment. To test this thesis the hatchability 2.469* 15 121 Treatment Xsires of control eggs was compared to the differ5 240 4.898** Sires Xstorage 5 86 1.755 Sires X (preheat vs. no preheat) ence between the pre-heated and control Sires Xstorage X (preheat vs. no 5 36 .735 preheat) eggs for each hen. The data represented by 49 Treatment Xdams within sires 33 th graph of Figure 1 is a combination of 67 Total the 1 hour and control data for both years. ** Significant at the one percent level. It can be seen from this graph that the eggs * Significant at the five percent level. from hens with normal hatchability above were 2 more degrees of freedom because 60 to 65% are adversely affected by preof the additional treatment. The term stor- incubation warming. It will be noted that age in the tables applies to the two age there is not a great deal of difference in this "break-even" point when egg age is groups of eggs. In both years there was a highly signifi- considered. This graph also indicates that cant treatment effect. When this compo- the greatest response is obtained with hens nent of the analysis was partitioned into that normally have a very low hatchability. its various parts it was found, as would be The same type of relationship existed for expected on the basis of the work of Kosin the two pre-heating treatments of 1959 (1954), that the difference between age (Figure 2). These data tend to support groups was highly significant. In the first the thesis that there is an optimum point year, the over-all combined difference of of embryo development at time of lay for 4% in favor of the treated eggs was signifi- best hatchability. cant. However, in 1959 the over-all comThe question also arises from the work bined difference of 3 % in favor of the TABLE 4.—Analysis of variance of the 1959 treated eggs was not significant but the hatchability data difference of 5% between the pre-heated Source of variation M.S. and control eggs of the 9 to 15 day period df Between dams 19 479 1.312 was significant. Between sires 5 799 2.189 Dams within sires 14 365 As shown in the analysis tables, there treatments 5 734 4.476* was no apparent difference in the response Between Storage 2,774 16.915* 5 hr. vs. 1 hr. 15 .091 of the different sire families to the pre1.067 Preheat vs. no preheat 175 Storage X (5 hr. vs. 1 hr.) 15 .091 heating treatment. It is felt, however, that Storage X (preheat vs. no preheat) 692 4.220* because of the limited number of sire fam- TreatmentXsires 1.000 25 164 Storage Xsires 5 160 .098 ilies in each year the possibility cannot be Sire X (5 hr. vs. 1 hr.) 5 231 1.409 Sire X (preheat vs. no preheat) 5 180 1.098 overlooked that there may be a difference Sire X storage X (5 hr. vs. 1 hr.) 5 201 1.223 Sire X storage X (preheat vs. no between other sire families. It is interesting preheat) 5 37 .226 to note that there was a significant sire X TreatmentXdams within sires storage interaction in 1958, indicating that Total the eggs of some sire families will with** Significant at the one percent level. stand storage better than others. * Significant at the five percent level. TABLE 3.—Analysis of variance of the 1958
hatchability data
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
816
F. L. CHERMS, JR.
Control
T=78.6-l6.1iX
1 to. treatment
20 JO E° 50 6? 70 So Control - Hatehablllty of fertile ^gc
50
100
FIG. 1. The difference in hatchability of fertile eggs (H.F.E.) of one hour warmed eggs and control eggs for 1958 and 1959 plotted against the hatchability of fertile eggs of the control eggs of both years.
previously reported (loc. cite) as to whether or not the response of eggs which are about two weeks old when set is further magnified with older eggs. To test this possibility, eggs were saved for four weeks for one hatch within each year. The results
2 nk.
3 He.
It »k.
Age then set
FIG. 3. Influence of age of egg when set on the hatchability of fertile eggs of one hour warmed eggs and of control eggs.
of these hatches, as shown in Figure 3, suggest that there is a greater response with the older eggs. However, the increase in hatchability does not seem to be great enough to recommend this procedure in handling eggs older than two weeks of age. SUMMARY
In two years of study, a significant response was obtained to 1 hour of preincubation warming of turkey eggs. This response appeared in eggs which were 9 to 15 days old when set. No additional increase in hatchability could be shown when the eggs were warmed for 5 hours. With the stock used in this study, no significant sire effect on the treatment response could be demonstrated. This does not rule out the possibility that such an effect might exist in other sire families. Eggs from dams with a normal hatchability over 60 to 65% are adversely af0 10 20 30 1)0 SO 60 70 80 90 100 Control - Hatchability of Fertile Eggs (1-lU days) fected by the warming treatment. The best FIG. 2. Difference in hatchability of fertile eggs response is obtained from hens with ex(H.F.E.) of one hour warmed eggs and control eggs, tremely low normal hatchability. and five hour warmed eggs and control eggs for 1959 plotted against the hatchability of fertile eggs of the control eggs for 1959.
REFERENCES Becker, W. A., and G. E. Bearse, 1958. Pre-incuba-
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
"S
Y'Jkil-W)*-
817
PRE-INCUBATION WARMING OF EGGS tion warming and hatchability of chicken eggs. Poultry Sci. 37 : 944-948. Jackson, H. W., 1912. Experiments in incubation. Pennsylvania Agr. Exp. Stat. Bui. 120. Kosin, I. L., 1954. Length of pre-incubation stor-
age and heredity as factors affecting hatchability of turkey eggs. Poultry Sci. 33: 24-28. Kosin, I. L., 1956. Studies on pre-incubation warming of chicken and turkey eggs. Poultry Sci. 35: 1384-1392.
Tameness and Its Relation to Aggressiveness and Productivity of the Domestic Chicken 1 TOORU KOMAI2 AND A . M . GUHL Department of Poultry Husbandry and Department of Zoology, Kansas State University,
Manhattan
T
HE behavior of chickens is recognized as an important factor in poultry management because behavior influences production and fertility. Summaries of information on their behavior have been made by Guhl (1953) and Wood-Gush (1955). Attention has been focused on aggressive-submissive behavior, the resultant peck-order, and the function of the social order in the various activities within the flock. There are other behavior traits which often affect the performance of individuals or flocks. Some of these are tameness or wildness as shown by flightiness which may involve relative sensitivity or nervousness; activity level; curiosity; and fearfulness. Each individual shows varying degrees of these traits along with its characteristic level of aggressiveness and submissiveness. Although these terms are in common usage, they are difficult to define precisely. Attempts to measure any one of these traits qualitatively and quantitatively are confounded by their interrelationships, e.g., a relatively inactive or phlegmatic individual
1 Contribution No. 248, Department of Poultry Husbandry, and No. 294, Department of Zoology, Kansas Agricultural Experiment Station, Kansas State University, Manhattan. 2 Present address: College of Agriculture, Kyoto University, Kyoto, Japan.
may show aggression infrequently although it may be the dominant bird in the flock. Thus the frequency of pecking is not necessarily a reliable measure of the level of aggressiveness. Furthermore, the frequency at which these traits may be expressed varies in time as a result of learning or conditioning, or because stimulus situations change. Observations reported here are from an attempt to measure the relative tameness of several strains of chickens and to relate these measures to aggressiveness and productivity. Tameness and wildness pertain to the reactions of an animal towards man. Scott and Fredericson (1951) define "tameness" as the absence of conflict behavior, and "wildness" as the tendency to escape. Hediger (1950, 1955) measured the degree of tameness by flight-distance, which is the specific distance at which an animal takes flight from an approaching enemy or man. A flight-distance of zero indicates complete tameness. The adjustment to man is often judged by the animal's willingness to take food, undeterred by the presence of man at a given distance. Hediger's concept of wildness is essentially flightiness. His technique was modified in the present study for measuring the tameness of chickens. The stimulus value of man was standardized by limiting the reactions to two individuals, and by the relative immobility of the observers within the
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
(Received for publication September 28. 1959)
Department of Poultry Husbandry, University of Wisconsin, Madison (Received for publication September 25, 1959)
T
PROCEDURE
The stock used in this study was the trapnested Station flock of Broad Breasted Bronze turkeys. In 1958 there were 136 females started in 11 single male mating pens, and in 1959 there were 110 females started in 10 single male mating pens. The eggs were all marked in the usual manner with the hen number, pen number, and date laid. Eggs were held in an egg holding room at about 55°F. at the research farm for 7 days and then they were delivered to the hatchery for treatment. Before being treated, the eggs were sorted by hens within pens and by date within hens. Then the eggs were assigned to the treatments, with every other egg from a hen being assigned to the same treatment in 1958 and every third egg to the same treatment in 1959. The following treatments were * Published with the approval of the Director of the Wisconsin Agricultural Experiment Station, College of Agriculture, Madison, Wisconsin.
tested: 1) in 1958 the eggs were heated for 1 hour at 100°F., and 2) in 1959 the eggs were heated for 1 and 5 hours at 100°F. Once the eggs had been assigned to the treatments they were reshuffled so that all of the eggs on one treatment were placed together. Then, those to be pre-heated were placed in pre-warmed incubators while the control eggs were maintained at room temperature until the treatment was finished. After completion of the treatment the eggs were immediately placed in an egg cooler which was maintained at 50°F. Settings were made every two weeks and therefore the eggs that were 9 to 15 days old when set where in the cooler for one week while the eggs which were 2 to 8 days old when set were in the cooler overnight. The youngest eggs set were 2 days of age instead of 1 day because of time needed to complete the procedure just described. All eggs were candled at 7 days of incubation and those which were said to be infertile were broken out to check for early dead embryos. The eggs were again candled at 24 days and then placed in pedigree hatching trays. When the hatch was taken off, the usual procedure was followed when pedigreeing. RESULTS AND DISCUSSION
A total of 3,757 fertile eggs was involved in the 1958 experiment and 2,550 fertile eggs in the 1959 experiment. The breakdown of the number of fertile eggs by hatches and treatments for each year is shown in Table 1. The smaller number of fertile eggs in 1959 can be accounted for
813
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
HE apparent increase in hatchability of turkey eggs when submitted to a pre-incubation period of warming as reported by Kosin (1956) and of chicken eggs as shown by Jackson (1912) and Becker and Bearse (1958) raises the question as to whether there is a genetic effect on this response. If such an effect exists, it may be a clue as to why certain sire families exhibit higher hatchability than do other families. This study was designed so as to determine if there are sire family differences in the response to pre-incubation warming.
814
F. L. CHERMS, JR.
TABLE 1.—The number of fertile eggs by hatches, treatments, and years in the pre-incubation warming study 1958 lhr. warming
Control
Stored
Stored
Date hatched
1/30 3/13 3/27 4/10
2-8 days
9-15 days
2-8 days
9-15 days
272 253 234 221
276 255 196 197
264 250 238 202
266 243 191 199
980
924
954
899
5 hr. warming Date hatched
1/15 2/12 2/26 4/23
Control
hr. warming
Stored
Stored
Stored
2-8 days
9-15 days
2-8 days
9-15 days
2-8 days
9-15 days
109 129 126 61
97 114 141 65
106 127 126 61
95 126 138 67
107 125 138 68
91 125 136 72
425
417
420
426
438
424
by the fewer number of hens and a decrease in fertility of about 10% in 1959. When the data for all dam and sire families are combined (Table 2) there does not appear to be any improvement in hatchability of the eggs that were 2 to 8 days old when set. However, treated eggs that were 9 to 15 days old when set hatched 7% better than the control eggs in 1958 and 5% better in 1959. Warming of eggs for 5 hours gave about the same response as did 1 hour warming. A separate analysis of variance was calculated for the data obtained in both years to test if the difference between treatments
was significant and also to determine if there was a significant sire effect on the response to warming (Tables 3 and 4). Both sets of calculations were made on the averages of the dams within each sire. Data were available by daughters within dams and also by hatches but it was felt that the information wanted could be obtained by the analysis reported here. In the analysis of the 1958 data it will be noted that there are 3 degrees of freedom for treatments. This includes the following categories: 1) 2 to 8 day pre-heated eggs, 2) 2 to 8 day controls, 3) 9 to 15 day pre-heated eggs, and 4) 9 to 15 day controls. In 1959 there
TABLE 2.—General hatchability response to pre-incubation warming of turkey eggs Stored 2-8 days Year 1958 1959
Stored 9-15 days
5hr. warming
1 hr. warming
Control
5hr. warming
lhr. warming
Control
65
67 64
66 64
59
58 59
51 54
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
1959
PRE-INCUBATION WARMING OF EGGS
815
Kosin (1956) discusses the possibility that eggs with a high hatchability potential probably have attained the optimum state Source of variation d M.S. F of embryological development. It seems Between dams 16 449 .968 Between sires 5 415 .894 logical to assume then that eggs from hens D a m s within sires 464 11 of normally high hatchability might be ad3 1,245 2 5 . 4 0 8 " Between treatments 1 3,332 68.000** Storage versely affected by the pre-heating treat1 313 6..189* Preheat vs. no preheat 1 89 1.816 Storage X (preheat vs. no preheat) ment. To test this thesis the hatchability 2.469* 15 121 Treatment Xsires of control eggs was compared to the differ5 240 4.898** Sires Xstorage 5 86 1.755 Sires X (preheat vs. no preheat) ence between the pre-heated and control Sires Xstorage X (preheat vs. no 5 36 .735 preheat) eggs for each hen. The data represented by 49 Treatment Xdams within sires 33 th graph of Figure 1 is a combination of 67 Total the 1 hour and control data for both years. ** Significant at the one percent level. It can be seen from this graph that the eggs * Significant at the five percent level. from hens with normal hatchability above were 2 more degrees of freedom because 60 to 65% are adversely affected by preof the additional treatment. The term stor- incubation warming. It will be noted that age in the tables applies to the two age there is not a great deal of difference in this "break-even" point when egg age is groups of eggs. In both years there was a highly signifi- considered. This graph also indicates that cant treatment effect. When this compo- the greatest response is obtained with hens nent of the analysis was partitioned into that normally have a very low hatchability. its various parts it was found, as would be The same type of relationship existed for expected on the basis of the work of Kosin the two pre-heating treatments of 1959 (1954), that the difference between age (Figure 2). These data tend to support groups was highly significant. In the first the thesis that there is an optimum point year, the over-all combined difference of of embryo development at time of lay for 4% in favor of the treated eggs was signifi- best hatchability. cant. However, in 1959 the over-all comThe question also arises from the work bined difference of 3 % in favor of the TABLE 4.—Analysis of variance of the 1959 treated eggs was not significant but the hatchability data difference of 5% between the pre-heated Source of variation M.S. and control eggs of the 9 to 15 day period df Between dams 19 479 1.312 was significant. Between sires 5 799 2.189 Dams within sires 14 365 As shown in the analysis tables, there treatments 5 734 4.476* was no apparent difference in the response Between Storage 2,774 16.915* 5 hr. vs. 1 hr. 15 .091 of the different sire families to the pre1.067 Preheat vs. no preheat 175 Storage X (5 hr. vs. 1 hr.) 15 .091 heating treatment. It is felt, however, that Storage X (preheat vs. no preheat) 692 4.220* because of the limited number of sire fam- TreatmentXsires 1.000 25 164 Storage Xsires 5 160 .098 ilies in each year the possibility cannot be Sire X (5 hr. vs. 1 hr.) 5 231 1.409 Sire X (preheat vs. no preheat) 5 180 1.098 overlooked that there may be a difference Sire X storage X (5 hr. vs. 1 hr.) 5 201 1.223 Sire X storage X (preheat vs. no between other sire families. It is interesting preheat) 5 37 .226 to note that there was a significant sire X TreatmentXdams within sires storage interaction in 1958, indicating that Total the eggs of some sire families will with** Significant at the one percent level. stand storage better than others. * Significant at the five percent level. TABLE 3.—Analysis of variance of the 1958
hatchability data
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
816
F. L. CHERMS, JR.
Control
T=78.6-l6.1iX
1 to. treatment
20 JO E° 50 6? 70 So Control - Hatehablllty of fertile ^gc
50
100
FIG. 1. The difference in hatchability of fertile eggs (H.F.E.) of one hour warmed eggs and control eggs for 1958 and 1959 plotted against the hatchability of fertile eggs of the control eggs of both years.
previously reported (loc. cite) as to whether or not the response of eggs which are about two weeks old when set is further magnified with older eggs. To test this possibility, eggs were saved for four weeks for one hatch within each year. The results
2 nk.
3 He.
It »k.
Age then set
FIG. 3. Influence of age of egg when set on the hatchability of fertile eggs of one hour warmed eggs and of control eggs.
of these hatches, as shown in Figure 3, suggest that there is a greater response with the older eggs. However, the increase in hatchability does not seem to be great enough to recommend this procedure in handling eggs older than two weeks of age. SUMMARY
In two years of study, a significant response was obtained to 1 hour of preincubation warming of turkey eggs. This response appeared in eggs which were 9 to 15 days old when set. No additional increase in hatchability could be shown when the eggs were warmed for 5 hours. With the stock used in this study, no significant sire effect on the treatment response could be demonstrated. This does not rule out the possibility that such an effect might exist in other sire families. Eggs from dams with a normal hatchability over 60 to 65% are adversely af0 10 20 30 1)0 SO 60 70 80 90 100 Control - Hatchability of Fertile Eggs (1-lU days) fected by the warming treatment. The best FIG. 2. Difference in hatchability of fertile eggs response is obtained from hens with ex(H.F.E.) of one hour warmed eggs and control eggs, tremely low normal hatchability. and five hour warmed eggs and control eggs for 1959 plotted against the hatchability of fertile eggs of the control eggs for 1959.
REFERENCES Becker, W. A., and G. E. Bearse, 1958. Pre-incuba-
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
"S
Y'Jkil-W)*-
817
PRE-INCUBATION WARMING OF EGGS tion warming and hatchability of chicken eggs. Poultry Sci. 37 : 944-948. Jackson, H. W., 1912. Experiments in incubation. Pennsylvania Agr. Exp. Stat. Bui. 120. Kosin, I. L., 1954. Length of pre-incubation stor-
age and heredity as factors affecting hatchability of turkey eggs. Poultry Sci. 33: 24-28. Kosin, I. L., 1956. Studies on pre-incubation warming of chicken and turkey eggs. Poultry Sci. 35: 1384-1392.
Tameness and Its Relation to Aggressiveness and Productivity of the Domestic Chicken 1 TOORU KOMAI2 AND A . M . GUHL Department of Poultry Husbandry and Department of Zoology, Kansas State University,
Manhattan
T
HE behavior of chickens is recognized as an important factor in poultry management because behavior influences production and fertility. Summaries of information on their behavior have been made by Guhl (1953) and Wood-Gush (1955). Attention has been focused on aggressive-submissive behavior, the resultant peck-order, and the function of the social order in the various activities within the flock. There are other behavior traits which often affect the performance of individuals or flocks. Some of these are tameness or wildness as shown by flightiness which may involve relative sensitivity or nervousness; activity level; curiosity; and fearfulness. Each individual shows varying degrees of these traits along with its characteristic level of aggressiveness and submissiveness. Although these terms are in common usage, they are difficult to define precisely. Attempts to measure any one of these traits qualitatively and quantitatively are confounded by their interrelationships, e.g., a relatively inactive or phlegmatic individual
1 Contribution No. 248, Department of Poultry Husbandry, and No. 294, Department of Zoology, Kansas Agricultural Experiment Station, Kansas State University, Manhattan. 2 Present address: College of Agriculture, Kyoto University, Kyoto, Japan.
may show aggression infrequently although it may be the dominant bird in the flock. Thus the frequency of pecking is not necessarily a reliable measure of the level of aggressiveness. Furthermore, the frequency at which these traits may be expressed varies in time as a result of learning or conditioning, or because stimulus situations change. Observations reported here are from an attempt to measure the relative tameness of several strains of chickens and to relate these measures to aggressiveness and productivity. Tameness and wildness pertain to the reactions of an animal towards man. Scott and Fredericson (1951) define "tameness" as the absence of conflict behavior, and "wildness" as the tendency to escape. Hediger (1950, 1955) measured the degree of tameness by flight-distance, which is the specific distance at which an animal takes flight from an approaching enemy or man. A flight-distance of zero indicates complete tameness. The adjustment to man is often judged by the animal's willingness to take food, undeterred by the presence of man at a given distance. Hediger's concept of wildness is essentially flightiness. His technique was modified in the present study for measuring the tameness of chickens. The stimulus value of man was standardized by limiting the reactions to two individuals, and by the relative immobility of the observers within the
Downloaded from http://ps.oxfordjournals.org/ at Georgetown University on May 23, 2015
(Received for publication September 28. 1959)