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Ease of capture in lines of Japanese quail Coturnix
/
japonica subjected to contrasting selection for fear
or sociability
Andrew D. Mills
), Jean M. Faure
Station de Recherches AÕicoles, Equipe Biologie du Comportement et Adaptation des Oiseaux, Institut
National de la Recherche Agronomique, Centre de Tours, 37380 Nouzilly, France
Accepted 22 March 2000
Abstract
Ž .
Japanese quail Coturnix japonica of lines, which have been subjected to contrasting selection
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for duration of the tonic immobility TI reaction or social reinstatement SR behaviour over many generations show corresponding differences in underlying fearfulness and sociality. As fearfulness and sociality are particularly influential traits in domesticated species, the finding that such traits respond to artificial selection may have important implications for poultry welfare and performance. However, it is not known if or how such selection has influenced human–animal interactions. The present experiment investigated the influence of fearfulness and SR behaviour on the ease with which birds could be caught and handled. Birds of lines selected for duration of the
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TI response or SR behaviour were reared in mixed line groups LTI and STI or HSR and LSR of 491 and 346 birds, respectively, until 6 weeks of age. When the birds were 2, 4, and 6 weeks of age, they were caught one by one and their individual capture ranks noted. In the group of birds selected for duration of the TI response, birds selected of the line selected for short duration of TI were caught before those selected for long duration of the response. In the group of birds selected for SR motivation, birds of the high line were caught before their low lines counterparts. Coefficients of concordance between capture ranks were significant and capture ranks did not differ significantly across ages. These results imply that selection for low levels of fear or high levels of sociality produces animals that are less disturbed by human interventions than animals selected for the opposite traits. The greater ease of capture of low fear line birds than high fear line birds may be explained by reduced fear of humans. The fact that the birds selected for high levels of SR behaviour are easier to catch than birds selected for low levels of sociality is less
)Corresponding author. Tel.:q33-2-47-42-78-37; fax:q33-2-47-42-77-78.
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E-mail address: mills@tours.inra.fr A.D. Mills .
0168-1591r00r$ - see front matterq2000 Elsevier Science B.V. All rights reserved.
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readily explicable. One hypothesis is that HSR line chicks tend to be more strongly imprinted on each other and the human caretaker. However, SR behaviour is highly species specific in both lines, existing evidence for line differences in social discrimination is limited and birds of the two lines show similar duration of the TI response. Despite this, whatever their underlying causation, these results demonstrate that genetic selection can be used to reduce negative reactions to human beings and may be of value in the improvement of both animal welfare and productivity.q2000
Elsevier Science B.V. All rights reserved.
Keywords: Japanese quail; Coturnix japonica; Capture; Fear; Stress; Sociality; Genetics; Welfare
1. Introduction
Whatever the species of animal or the type of husbandry system considered, interactions between humans and animals are of importance with respect to both production traits and welfare. Human activity is a frequent cause of disturbance in many husbandry systems. Such disturbance may cause falls in production and welfare ŽHemsworth and Barnett, 1989; Hemsworth et al., 1989; Seabrook, 1990 . In the case of. large animals such as cattle, the stockman risks injury or even death if husbandry practices are such that the animals become aggressive or make intemperate attempts at
Ž .
flight or avoidance Le Neindre et al., 1994 . In smaller species, contact with humans Ž
may lead to fear, distress and adverse effects on production traits Rushen and de .
Pasille, 1992; Hemsworth et al., 1994; Jones, 1996 . For examples, in poultry, aversive manipulations during ‘harvesting’ and transport prior to slaughter can lead to stress and
Ž .
consequent falls in meat quality Duncan et al., 1986; Remignon et al., 1998 and inappropriate fear reactions may lead to panic and the death of birds because of suffocation or trampling as hundreds or even thousands of birds crowd in to the corners
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of the poultry house Mills and Faure, 1990a . Furthermore, all or any of the above may lead to negative public opinion concerning the husbandry and management of domestic
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animals Faure and Mills, 1995 .
Despite the evident importance of interactions between humans and animals, there appear to have been few studies of such interactions under conditions that approach those found in commercial husbandry systems. Environmental or ontogenetic influences on animals’ responses to humans have been extensively studied in both birds and
Ž
mammals under experimental conditions examples include: Murphy and Duncan, 1977, 1978; Gross and Siegel, 1979; Jones, 1985, 1987, 1993; Jones and Faure, 1981; Jones and Waddington, 1992; Jones et al., 1981; Boissy and Bouissou, 1988; Pedersen and
.
Jeppersen, 1990; Barnett et al., 1993; Hemsworth and Jones, 1993 . However, the role of Ž
genetic factors in human–animal reactions has received less attention exceptions include: Belyaev, 1978; Belyaev and Trut, 1975; Belyaev et al., 1985; Bessei et al.,
.
1983; Le Neindre et al., 1994; Satterlee and Jones, 1997 . This apparent lack of attention to genetic factors in the improvement of human–animal interactions is surprising for
Ž . Ž .
Ž
wild ancestors Poole, 1972; Desforges and Wood-Gush, 1975; Ajayi et al., 1978; Saad .
et al., 1984 . Third, limited evidence, that selection for the quality of human–animal Ž
relationships is possible already, exists Belyaev and Trut, 1975; Le Neindre et al., .
1994 .
In the present study, we studied the effects of selection for duration of the tonic
Ž . Ž . Ž .
immobility TI response a putative measure of fearfulness or social reinstatement SR
Ž .
motivation a putative measure of sociality on the ease of capture of Japanese quail at
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various ages. We also studied the consistency ‘repeatability’ of individual capture ranks at different ages.
2. Materials and methods
2.1. Animals
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The animals used were Japanese quail Coturnix japonica and were the issue of the F15 generations of lines selected for long or short duration of the TI response or high or low levels of SR behaviour. SR behaviour was measured in the treadmill test described
Ž .
by Mills and Faure 1990b . During the course of the development of these lines,
Ž . Ž .
selection for long LTI or short STI duration of the TI response has been weighted for
Ž . Ž .
independence from SR behaviour and selection for high HSR or low LSR levels of SR behaviour has been weighted for independence from duration of the TI response. A full description of these lines and the methods used during their selection is given in
Ž .
Mills and Faure 1991 . Means and standard deviations for duration of TI, level of SR and body weight at 2 weeks of age are given in Table 1 for animals of the same generation.
Eggs were collected ‘straight-run’ from the breeding populations of the LTI and STI or HSR and LSR lines over a period of 2 weeks. The breeding population of each line consisted of 20 males and 40 females; each male being mated to two females. Eggs from the TI and SR lines were collected, incubated and hatched on different dates, but thereafter husbandry and experimental procedures were identical. During the collection
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period, eggs were stored at ambient temperature f208C in the same poultry house as the breeding birds. At the end of the collection period, the number eggs per line was
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adjusted such that the number of chicks of each line LTI and STI or HSR and LSR
Table 1
Median"standard deviation for duration of tonic immobility, level of social reinstatement and 2-week body weight of the four strains
Ž . Ž . Ž .
Tonic immobility s Social reinstatement arbitrary units 2-week body weight g
LTI 191"94 144"295 94.6"9.6
STI 14"26 440"436 85.1"9.3
HSR 45"41 1321"656 73.3"7.1
expected to hatch would be approximately equal to 250. The eggs were then incubated
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and hatched in commercial Eltex, France incubators and hatchers. Eggs from the STI and LTI lines or the HSR and LSR lines were incubated and hatched together although separate trays were used for each line. All chicks were wing-tagged on the day of hatching. The chicks were sexed, on the basis of plumage colour and form, when they
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were 4 weeks old Lucotte, 1974 . A low hatch rate in the SR lines, mortality and loss of wing-tags resulted, by the end of the experiment, in the total number of TI line birds
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being 491 STIs250 and LTIs241 and the number of SR line birds being 346 ŽHSRs178 and LSRs168 . The 250 STI line birds comprised of 138. ?? and 112
YY, the 241 LTI line birds comprised of 124 ?? and 117 YY, the 178 HSR line birds comprised of 90?? and 88YY and the 168 LSR line birds comprised of 65 ??and 103YY.
2.2. Husbandry
From the day of hatching onwards, the chicks were housed, in mixed line groups
Ž . 2
LTI and STI or HSR and LSR , in rooms with a floor area of 16 m . The floors of the rooms were covered with wood shavings. Heat was provided by gas burners suspended from the roofs of the rooms. The temperature directly below the burners was 388C, and the average temperature in the whole room was 258C. During the period following hatching, the temperature of the burners was progressively reduced in a manner such that by the time the chicks were 3 weeks of age, the ambient temperature in the rooms was 228C. This temperature was maintained until the end of the experiment. From the day of hatching to the time when the chicks were 3 weeks old, the lighting regimen was continuous illumination. From the time the birds were 3 weeks of age to the end of the experiment the lighting regimen was 8L:16D. Food and water were available ad libitum at all times. From hatching to 3 weeks of age the chicks were fed on a commercial game
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bird starter diet Godet, France . From 3 weeks of age onwards they were fed on a Ž .
‘finisher’ diet formulated as recommended by INRA 1984 . Except during
experimenta-Ž .
tion see below , disturbance of the animals were kept to the minimum required for routine feeding, watering and maintenance. In the TI line group the stocking density was 31 birdsrm2. In the SR line group, the stocking density was 27 birdsrm2.
2.3. Experimental procedures
When the birds were 2, 4 and 6 weeks of age they were subjected to a capture test.
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Table 2
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Median"median absolute deviation MAD and summary statistics for comparative capture ranks of Japanese
Ž . Ž .
quail subject to selection for long LTI or short STI duration of the tonic immobility response. Capture tests were performed when the birds were 2, 4 and 6 weeks of age. Within each age group, capture ranks were compared using the Mann–Whitney U test
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Line Age weeks Count Median rank"MAD Rank sum U P
LTI 250 324"106 73,537
2 42,162 -0.001
STI 241 184"184 47,249
LTI 250 306"109 72,293
4 40,917 -0.001
STI 241 181"110 48,493
LTI 250 334"98 76,167
6 44,791 -0.001
STI 241 172"98 44,619
2.4. Statistical analyses
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Data were expressed as medians"median absolute deviations MAD . If two birds were caught simultaneously or their wing-tag numbers misread, birds were given their average capture rank. Birds, which died during the course of the experiment, were excluded from the analyses and the data re-ranked accordingly. Between line and between sexes, comparisons of capture ranks, at a given age, were tested using Mann–Whitney U tests. The consistency of capture rank at 2, 4 or 6 weeks of age was estimated, both across and within lines, using Friedman’s two-way analysis of variance
Ž .
and Kendal’s coefficient of concordance Siegel, 1956 . In the tables, capture ranks are
Ž .
expressed as absolute medians "MAD All statistical tests were carried out using the
Table 3
Ž .
Median"median absolute deviation MAD and summary statistics for comparative capture ranks of Japanese
Ž . Ž .
quail subject to selection for high HSR or low LSR levels of social reinstatement motivation. Capture tests were performed when the birds were 2, 4 and 6 weeks of age. Within each age group, capture ranks were compared using the Mann–Whitney U test
Ž .
Line Age weeks Count Median rank"MAD Rank sum U P
HSR 178 154"81 27,104
2 11,173 -0.001
LSR 168 218"87 32,927
HSR 178 153"78 27,811
4 1180 -0.001
LSR 168 203"95 32,219
HSR 178 143"82 26,277
6 10,346 -0.001
Table 4
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Median"median absolute deviation MAD and summary statistics for comparative capture ranks of male and
Ž . Ž .
female Japanese quail subject to selection for long LTI or short STI duration of the TI response. Capture tests were performed when the birds were 2, 4 and 6 weeks of age. Within each age group, capture ranks were compared using the Mann–Whitney U test
Ž .
Lines Age weeks Sex Count Median rank"MAD Rank sum U P
LTI and STI ? 262 237"116 63,581
2 29,128 0.31
LTI and STI Y 229 256"132 57,205
LTI and STI ? 262 244"110 64,655
4 30,202 0.90
LTI and STI Y 229 247"132 56,130
LTI and STI ? 262 261"113 67,099
6 32,646 0.09
LTI and STI Y 229 231"125 53,686
w
Ž . w
Ž .
SYSTAT 5 SYSTAT, Evanston, IL , STATVIEW Abacus Concepts, Berkely, CA w
Ž .
and EXSTATIX Select Microsystems, New York computer statistic packages.
3. Results
3.1. Has contrasting selection for fearfulness or SR motiÕation influenced ease of
capture?
Ž .
The median "MAD capture ranks of STI and LTI birds or HSR and LSR birds at 2, 4 and 6 weeks of age are shown in Tables 2 and 3, respectively. Irrespective of their age, STI line animals tended to be caught before LTI line animals and HSR line animals
Ž
were captured before LSR line animals P-0.001; Mann–Whitney U tests in all .
cases .
Table 5
Ž .
Median"median absolute deviation MAD and summary statistics for comparative capture ranks of male and
Ž . Ž .
female Japanese quail subject to selection for high HSR or low LSR levels of social reinstatement behaviour. Capture tests were performed when the birds were 2, 4 and 6 weeks of age. Within each age group, capture ranks were compared using the Mann–Whitney U test
Ž .
Lines Age weeks Sex Count Median rank"MAD Rank sum U P
HSR and LSR ? 155 179"91 26,144
2 14,054 0.42
HSR and LSR Y 191 191"98 33,887
HSR and LSR ? 155 170"86 26,477
4 14,387 0.65
HSR and LSR Y 191 180"92 33,553
HSR and LSR ? 155 155"87 25,267
6 13,177 0.08
Table 6
Non-parametric analysis of capture ranks in STI and LTI line birds or HSR and LSR line birds. The statistics
Ž 2. 2
presented are N, the Friedman test statistic xr , the probability of xr , the Kendall coefficient of
Ž . Ž 2.
concordance between scores at a given age W , the chi-square x associated with each value of W and its corresponding probability
2 2
Line N xr P W x P
LTI and STI 491 0.05 0.98 0.63 932 P-0.001
LTI 241 0.22 0.89 0.53 382 P-0.001
STI 250 0.09 0.96 0.62 462 P-0.001
HSR and LSR 346 1.71 0.43 0.57 589 P-0.001
HSR 178 2.04 0.36 0.51 272 P-0.001
LSR 168 0.59 0.74 0.57 284 P-0.001
3.2. Does gender influence ease of capture in lines selected for fearfulness or SR motiÕation?
Ž .
The medians "MAD capture ranks of ? or Y STI and ? or Y LTI birds are
Ž .
shown in Table 4. The median "MAD capture ranks ofYand? HSR and LSRY
and ? birds are shown in Table 5. At a given age and within lines, there were no
Ž
significant differences, in capture ranks, betweenYYand?? P)0.05; Mann–Whit-.
ney U tests in all cases . Therefore, the sex of the animals was not taken into account in subsequent analyses.
( )
3.3. Are indiÕidual capture ranks consistent ‘repeatable’ across ages?
Friedman two-way analysis of variance indicated that capture rank at 2, 4 or 6 weeks
Ž .
of age did not differ between individuals whatever their line Table 6 . Kendall’s
Ž .
coefficient of concordance indicated a strong agreement P-0.001 between capture
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ranks at all ages irrespective of line Table 6 .
4. Discussion
capture ranks. However, none of these factors explains the line differences or the agreement between capture ranks that strongly imply consistency in both lines and individual capture ranks.
The findings of this study seem, at first sight, to be at odds with previously published Ž .
papers. First, Bessei 1979 selected Japanese quail for high or low levels of locomotor
Ž .
activity, and found reduced levels of fearfulness Jones et al., 1982 together with a
Ž . Ž .
reduced ease of capture Bessei et al 1983 . Second, Satterlee and Jones 1997 , found no line differences, in capture rank, between low-stress and high-stress lines of quail, but
Ž .
did find significant within line correlations. Third, Rahn and Ware 1980 found that heavier birds tended to be caught first. These discrepancies may be explained by
Ž . Ž .
differences in methodology. Both Bessei et al., 1983 and Satterlee and Jones 1997 housed their birds in small groups, and whether or not the experimenter was ‘blind’ or
Ž .
‘sighted’, freezing or crouching rather than active avoidance of the experimenter may Ž .
have been predominant factors in these experiments. Rahn and Ware 1980 corralled their birds, and found that heavier birds tended to be caught first. In this last case, the
Ž .
experimenter s were not blind and may have inadvertently selected heavier less active birds.
The observed differences in capture rank in the present experiment do not support an Ž .
effect of body weight as observed by Rahn and Ware 1980 . First, in the present
Ž .
experiment the lighter strains STI and HSR were caught first. Second, between line differences in capture ranks were greatest in the LTI and STI lines whereas the line differences in body weight were greatest in the HSR and LSR lines.
In the present experiment, the greater ease of capture of low fear line birds than high fear line birds may be explained by reduced fear of humans. The fact that the birds selected for high levels of SR behaviour are easier to catch than birds selected for low levels of sociality is less easily explained. Differences in fearfulness, seem unlikely because SR behaviour birds of the two lines show similar duration of the TI response ŽMills and Faure, 1991 . Socialization to the experimenters is equally unlikely because.
Ž .
SR behaviour is highly species specific in both lines Mills et al., 1995 and existing Ž
evidence for line differences in social discrimination is limited Jones et al., 1996; .
Carmichael et al. 1998 . Line differences in imprinting on the stockperson might explain the differences between the HSR and LSR lines but this hypothesis is purely speculative. However, whatever their underlying causation, these results demonstrate that genetic selection can be used to reduce negative reactions to human beings and may be of value in the improvement of both animal welfare and productivity. Furthermore, these results
Ž .
have implications for sampling theory, as Satterlee and Jones 1997 point out, if some birds are easier to catch than others, sampling procedures, which do not take into account this possibility risk experimental bias.
Acknowledgements
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