Ease of capture in lines of Japanese quail žcoturnix subjected to contrasting selection for fear or sociability

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1 Ž. Applied Animal Behaviour Science Ease of capture in lines of Japanese quail žcoturnix 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, Nouzilly, France Accepted 22 March 2000 Abstract Japanese quail Ž Coturnix japonica. of lines, which have been subjected to contrasting selection for duration of the tonic immobility Ž TI. reaction or social reinstatement Ž 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 TI response or SR behaviour were reared in mixed line groups Ž 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.: q ; fax: q Ž. address: mills@tours.inra.fr A.D. Mills r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž. PII: S X

2 126 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science 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. q 2000 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 Ž Hemsworth and Barnett, 1989; Hemsworth et al., 1989; Seabrook, 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 flight or avoidance Ž Le Neindre et al., In smaller species, contact with humans may lead to fear, distress and adverse effects on production traits ŽRushen and de Pasille, 1992; Hemsworth et al., 1994; Jones, For examples, in poultry, aversive manipulations during harvesting and transport prior to slaughter can lead to stress and consequent falls in meat quality Ž Duncan et al., 1986; Remignon et al., 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 of the poultry house Ž Mills and Faure, 1990a.. Furthermore, all or any of the above may lead to negative public opinion concerning the husbandry and management of domestic animals Ž Faure and Mills, 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 mammals under experimental conditions Žexamples 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, However, the role of genetic factors in human animal reactions has received less attention Žexceptions include: Belyaev, 1978; Belyaev and Trut, 1975; Belyaev et al., 1985; Bessei et al., 1983; Le Neindre et al., 1994; Satterlee and Jones, This apparent lack of attention to genetic factors in the improvement of human animal interactions is surprising for three reasons. First, as Mench Ž and Mills et al. Ž suggest, genetic selection may be a powerful tool for decreasing the incidence of welfare problems. Second, various studies have shown that domestic animals are more docile than their putative

3 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science wild ancestors ŽPoole, 1972; Desforges and Wood-Gush, 1975; Ajayi et al., 1978; Saad et al., Third, limited evidence, that selection for the quality of human animal relationships is possible already, exists ŽBelyaev and Trut, 1975; Le Neindre et al., In the present study, we studied the effects of selection for duration of the tonic immobility Ž TI. response Ž a putative measure of fearfulness. or social reinstatement Ž SR. motivation Ž a putative measure of sociality. on the ease of capture of Japanese quail at various ages. We also studied the consistency Ž repeatability. of individual capture ranks at different ages. 2. Materials and methods 2.1. Animals The animals used were Japanese quail Ž 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 by Mills and Faure Ž 1990b.. During the course of the development of these lines, selection for long Ž LTI. or short Ž STI. duration of the TI response has been weighted for independence from SR behaviour and selection for high Ž HSR. or low Ž 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 Mills and Faure Ž 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 period, eggs were stored at ambient temperature Ž f 208C. in the same poultry house as the breeding birds. At the end of the collection period, the number eggs per line was adjusted such that the number of chicks of each line Ž 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 Tonic immobility Ž. s Social reinstatement Ž arbitrary units. 2-week body weight Ž. g LTI 191"94 144" "9.6 STI 14"26 440" "9.3 HSR 45" " "7.1 LSR 41"33 127" "8.4

4 128 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science expected to hatch would be approximately equal to 250. The eggs were then incubated and hatched in commercial Ž 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 were 4 weeks old Ž Lucotte, 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 being 491 Ž STI s 250 and LTI s 241. and the number of SR line birds being 346 Ž HSRs178 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 88 YY and the 168 LSR line birds comprised of 65?? and 103 YY 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 bird starter diet Ž Godet, France.. From 3 weeks of age onwards they were fed on a finisher diet formulated as recommended by INRA Ž Except during experimentation Ž 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 birdsrm 2. In the SR line group, the stocking density was 27 birdsrm Experimental procedures When the birds were 2, 4 and 6 weeks of age they were subjected to a capture test. These capture tests involved two experimenters Ž ADM and JMF. entering the room and catching the birds one at a time with the minimum amount of disturbance possible. The birds were caught at random with the proviso that birds close to the experimenters and made no attempt to avoid them were likely to be caught first, whereas those birds, which actively avoided the experimenters were likely to be caught last. As soon as a bird was caught, its wing-tag number and its capture rank were recorded. After capture, the birds were placed in crates until being returned to their homeroom when all the birds had been caught.

5 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science Table 2 Median"median absolute deviation Ž MAD. and summary statistics for comparative capture ranks of Japanese quail subject to selection for long Ž LTI. or short Ž 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 Ž. Line Age weeks Count Median rank"mad Rank sum U P LTI "106 73, , STI "184 47,249 LTI "109 72, , STI "110 48,493 LTI "98 76, , STI "98 44, Statistical analyses Data were expressed as medians" median absolute deviations Ž 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 and Kendal s coefficient of concordance Ž Siegel, In the tables, capture ranks are expressed as absolute medians Ž "MAD. All statistical tests were carried out using the Table 3 Median"median absolute deviation Ž MAD. and summary statistics for comparative capture ranks of Japanese quail subject to selection for high Ž HSR. or low Ž 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 Line Age Ž weeks. Count Median rank"mad Rank sum U P HSR "81 27, , LSR "87 32,927 HSR "78 27, LSR "95 32,219 HSR "82 26, , LSR "90 33,754

6 130 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science Table 4 Median"median absolute deviation Ž MAD. and summary statistics for comparative capture ranks of male and female Japanese quail subject to selection for long Ž LTI. or short Ž 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? "116 63, , LTI and STI Y "132 57,205 LTI and STI? "110 64, , LTI and STI Y "132 56,130 LTI and STI? "113 67, , LTI and STI Y "125 53,686 SYSTAT 5 w Ž SYSTAT, Evanston, IL., STATVIEW w Ž Abacus Concepts, Berkely, CA. and EXSTATIX w Ž Select Microsystems, New York. computer statistic packages. 3. Results 3.1. Has contrasting selection for fearfulness or SR motiõation influenced ease of capture? The median Ž "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 were captured before LSR line animals Ž P ; Mann Whitney U tests in all cases.. Table 5 Median"median absolute deviation Ž MAD. and summary statistics for comparative capture ranks of male and female Japanese quail subject to selection for high Ž HSR. or low Ž 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 Lines Age Ž weeks. Sex Count Median rank"mad Rank sum U P HSR and LSR? "91 26, , HSR and LSR Y "98 33,887 HSR and LSR? "86 26, , HSR and LSR Y "92 33,553 HSR and LSR? "87 25, , HSR and LSR Y "86 34,764

7 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science 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 x r., the probability of x r, the Kendall coefficient of concordance between scores at a given age Ž W., the chi-square Žx 2. associated with each value of W and its corresponding probability 2 2 Line N xr P W x P LTI and STI P LTI P STI P HSR and LSR P HSR P LSR P Does gender influence ease of capture in lines selected for fearfulness or SR motiõation? The medians Ž "MAD. capture ranks of? or Y STI and? or Y LTI birds are shown in Table 4. The median Ž "MAD. capture ranks of Y and? HSR and LSR Y and? birds are shown in Table 5. At a given age and within lines, there were no significant differences, in capture ranks, between YY and?? Ž P) 0.05; Mann Whitney U tests in all cases.. Therefore, the sex of the animals was not taken into account in subsequent analyses Are indiõidual capture ranks consistent repeatable across ages? Friedman two-way analysis of variance indicated that capture rank at 2, 4 or 6 weeks of age did not differ between individuals whatever their line Ž Table 6.. Kendall s coefficient of concordance indicated a strong agreement Ž P between capture ranks at all ages irrespective of line Ž Table Discussion The results of the present study indicate that STI line birds and HSR line birds are more easily caught than their LTI or LSR line counterparts and that individual capture ranks are consistent from 2 to 6 weeks of age. However, capture was pseudo-random because the experimenter made two choices as to which bird was to be caught. First, he inevitably chose a bird was close to him and given the size of the experimental rooms, birds could easily avoid capture by moving away from the experimenter. This source of variation in capture ranks reflected the behaviour of the birds. Second, if two or more birds were at an equal distance from him, he made a subconscious choice as to which bird to catch. This may have resulted in an increased randomization of capture ranks since even birds, which were equidistant from the experimenter would receive different

8 132 A.D. Mills, J.M. FaurerApplied Animal BehaÕiour Science 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 papers. First, Bessei Ž selected Japanese quail for high or low levels of locomotor activity, and found reduced levels of fearfulness Ž Jones et al., together with a reduced ease of capture Ž Bessei et al Second, Satterlee and Jones Ž 1997., found no line differences, in capture rank, between low-stress and high-stress lines of quail, but did find significant within line correlations. Third, Rahn and Ware Ž found that heavier birds tended to be caught first. These discrepancies may be explained by differences in methodology. Both Bessei et al., Ž and Satterlee and Jones Ž housed their birds in small groups, and whether or not the experimenter was blind or sighted, freezing or crouching Ž rather than active avoidance of the experimenter. may have been predominant factors in these experiments. Rahn and Ware Ž corralled their birds, and found that heavier birds tended to be caught first. In this last case, the experimenterž. 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 effect of body weight as observed by Rahn and Ware Ž First, in the present experiment the lighter strains Ž 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 Ž Mills and Faure, Socialization to the experimenters is equally unlikely because SR behaviour is highly species specific in both lines Mills et al., Ž and existing evidence for line differences in social discrimination is limited ŽJones et al., 1996; Carmichael et al 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 have implications for sampling theory, as Satterlee and Jones Ž 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 We wish to thank Monique Marche for help with data collection and Jean Marie Brigand for care of the animals.

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