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Effect of rearing environment and change of environment on the behaviour of gilts
APPLIED ANIMAL BEHAVIOUR SCIENCE
Applied Animal Behaviour
Science46 ( 1995) 5745
Effect of rearing environment and change of environment on the behaviour of gilts V.E. Beattie a**, N. Walker a, I.A. Sneddon b aAgricultural Research Institute of Northern Ireland, Hillsborough, Co. Down, ET26 6DR. UK b School of Psychology, The Queen’s University of Belfast, Belfast, ET7 INN, UK Accepted 6 July 1995
Abstract
The effect of previous experience on the behaviour of gilts was investigated. Twenty gilts were reared, from birth to farrowing, in an enriched environment and 20 in a barren environment. Six weeks prior to the expected date of parturition the gilts underwent a handling test and an open field test. A few days prior to parturition the gilts were moved into farrowing accommodation. There were two farrowing environments, barren and enriched, and, using a crossover design, gilts were moved either to a similar environment to that which they had previously experienced, i.e. barren to barren (BB) or enriched to enriched (EE) or to a different environment, i.e. barren to enriched (BE) or enriched to barren (EB). Gilts from enriched environments were more difficult to drive, scored on a scale of l5 (B 1.2, E 1.8, SEM 0.18, P < 0.05) and vocalized more frequently in the 7 min test period (B 32.4, E 69.5, SEM 10.46, P <0.05) than gilts from barren environments while the latter gilts performed more locomotory behaviour in the open field test than their counterparts from enriched environments (B 10.6, E 8.9, SEM 0.44, P < 0.05). Gilts which experienced a change of environment at parturition exhibited more active behaviour than gilts which were moved to farrowing accommodation similar to the housing in which they were reared (BB 2%“, BE 28b, EE 7”, EB 27b, SEM 5.1, P < 0.01). The influence of the environment in determining pig behaviour is discussed with reference to the effects of past experience. Keywords: Pigs; Behaviour;
Past experience
1. Introduction
Ttte early experience of humans affects their cognitive, social and emotional development. Both physical and social influences of early environment are known to have an effect on * Corresponding 0168-1591/95/%09.50 SDI0168-1591(95)
author. Tel: Hillsborough
+44-1846-682484;
Fax: +44-1846689594.
0 1995 Elsevier Science B.V. All rights reserved
58
V.E. Beattie et al. /Applied Animal Behviour
Science 46 (1995) 5765
the subsequent behaviour of humans (Roff, 1974). This also has been shown to be true in many species of animals. For example, Appleby ( 1984) found that chicks reared in deep litter housing with no perches, when given perches at a later stage, neither knew nor could learn how to perch. Wood-Gush and Beilharz (1983) revealed that the behaviour of pigs can be determined by their early life experience. They found that pigs reared in a bare cage when given earth in a trough did not use it as much as pigs that had always had access to it. Behaviours influenced by the environment in early life are retained throughout the life of the growing pig. For example high levels of social behaviour developed by piglets in barren farrowing pens have been shown to remain even if the environment is changed (Schouten, 1991; Simonsen, 1992: Beattie et al., 1993). This study investigated whether housing environment affected behaviour of gilts in mid-gestation, at approximately 8 months of age and a few days prior to farrowing at approximately 8 months of age.
2. Animals, materials and method This study was based on a four treatment crossover design. Gilts were reared in either a barren (B) or enriched (E) environment and then farrowed in either the same or opposite environments. Their behaviour was recorded during three tests or events. Eleven Large White X Landrace multiparous sows were selected as dams for the gilts in this study. Five days prior to their expected date of parturition they were moved into fat-rowing crates (2.6 X 1.6 m*). Five of these sows and their litters remained in this environment throughout the 6 week suckling period. The other six sows with their litters were moved to large, straw bedded pens (3.6 X 2.2 m*) 3 days post partum, where they were housed for the remainder of the 6 week lactation. In both environments, the male pigs were weaned at 4 weeks of age to leave only the female piglets suckling the sow. Twenty gilts from the six enriched litters were weaned at 6 weeks of age, mixed and moved to a large enriched pen. This pen measured 10.3 X 4 m* with a kennel area (2.5 X 4 m’) at one end which served as a lying area and running along opposite sides of the pen two kerbed areas (3 X 1.5 m*) each containing approximately 5 cm depth of peat. Straw was accessible from two racks and feed was available ad libitum from six single space feeders (Verba Wet Feeder, L. Verbakel B.V.). When the gilts were 165-170 days old a mature boar was penned next to their pen but the housing did not allow visual or physical contact with the boar. The gilts remained in this enriched pen through puberty and mating until just prior to parturition. The 20 gilts reared in the barren fart-owing crate house were also weaned at 6 weeks of age, mixed and moved into a barren rearing environment. This consisted of 3.5 X 1 m* pens half of which was a kennel area. The gilts stayed in these pens until 8 weeks of age when they were divided into two groups of ten and moved into 3.5 X 1.5 m2 pens which had expanded metal floors where they remained until approximately 11 weeks of age. At this stage they were moved into fully slatted floored pens in groups of five. Boars were housed in adjoining pens separated from the gilts by barred windows, this allowed both visual and physical contact. The gilts remained in this housing until mating at approximately 200 days of age when they were housed individually in stalls where they remained until several days prior to their expected parturition date.
V.E. Beattie et al. /Applied
Animal Behaviour Science 46 (1995) 5745
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Fig. 1. Open field test pen.
Both environments at all stages had a day/night cycle, with full lighting between 09:OO and 17:00 h and dimmed lighting for the remainder of the time. From 10 days of age to 6 weeks of age piglets in both environments were offered a commercial creep feed. The diets offered from 6 to 12 weeks of age and from 12 weeks to mating contained 14.2 MJ digestible energy (DE) kg-’ and 13.4 MJ DE kg-‘, respectively. During pregnancy, gilts in both environments were offered daily 2.2 kg of a cereal/soya based diet supplying 13.4 MJ DE. The mean daily quantity of this diet offered during lactation was 5.5 kg. Water was continuously available in both environments and straw and peat were replenished as necessary in the enriched environment. Of the initial 20 gilts reared in each of the two environments, 16 were tested in the strange situation test. Due to lack of conception and lameness three of the enriched gilts had to be removed leaving only five enriched gilts to be moved into barren farrowing accommodation (Section 2.3). 2.1. Open jield test Six weeks prior to the expected parturition date the gilts were introduced individually to the open field test pen 9.2 X 3.0 m*. This area was divided into 12 equal rectangles, each measuring 2.3 X 1 .O m*, which were numbered in an anti-clockwise direction from 1 to 12 (Fig. 1) . Each gilt was left in the novel pen for 7 min during which all her behaviour was recorded using video. Two minutes into the test, a bucket was slowly lowered to approximately 0.5 m above the ground. The number of vocalizations and eliminations made by the gilt were recorded by direct observation throughout the test. The test pen was not cleaned out between tests; therefore, to preclude any treatment bias created by olfactory cues, the order of testing was randomized. All tests were carried out between 09:OO and 12:00 h. The video tapes were analysed to determine frequency and duration of visits to individual squares. Behavioural parameters based on the open field test developed by Stedman and
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Varley ( 1991) were used. These were as follows: number of novel squares visited, i.e. the number of squares visited by the pig that had not been visited before throughout the duration of the test; total number of squares visited throughout the duration of the test. The frequency of visits (number min- ‘) and the duration (s) of time spent in various combinations of squares were also calculated. The combinations were peripheral squares (all except 11 and 12)) central squares ( 11 and 12) and squares increasingly distant from the entrance ( 1, 2 and 3; 4, 10 and 11; 5,9 and 12; 6,7 and 8). The pig was recorded as being in a square if its head and front feet were in that square. 2.2 Handling test The responses to two handling procedures based on the work of Lawrence et al. ( 1991) were recorded during the transfer of gilts from resident pens to the test pen for the open field test The first handling test was ease of movement measured as the gilts moved individually down the corridor with Observer 1 walking behind. The ease of movement was scored subjectively using a scale from 1 to 5, the easier the movement the lower the score (Lawrence et al., 1991). Response to sudden human approach (threat) was the second human pig interaction test and as with ease of movement it was scored on a scale of l-5 (Lawrence et al., 1991). 2.3. Change of environment Five days prior to the expected date of parturition, eight gilts from the enriched housing were moved into pens (3.6 X 2.2 m2) bedded with straw and five were moved into farrowing crates. A similar crossover was carried out on the gilts from barren housing: eight were moved to crates prior to fart-owing and eight to straw bedded pens. Gilts in the enriched farrowing pens were not restrained at any time during the farrowing or preweaning period. The behaviour of each gilt was recorded for 60 s every 3 min, during the first hour after movement. Vocalizations and eliminations made by the gilts were recorded and all other behaviour was assigned to one of the following mutually exclusive and comprehensive behavioural categories derived from previous observations of sows: active behaviourwalking around the pen with head raised, neck extended, pushing against the sides of the crate or door of the pen, usually accompanied by vocalizations; do nothing-standing or sitting motionless with head in a relaxed position; lie down-lying laterally or in the recumbent position with eyes open or closed; exploratory-behaviour directed towards any substrate or the ground. The time spent in each category of behaviour is expressed as a percentage of the time observed. The frequency of vocalizations is presented as a mean frequency per minute while the frequency of eliminations is a mean frequency over the period of observation. 2.4. Performance The number of piglets born alive, birth weight and the number lain on or savaged by the dam was recorded.
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61
2.5. Statistical analysis Frequency of visits to a square or combination of squares was recorded as number of visits in 1 min. Duration was recorded as the time spent in seconds in a square or combination of squares during the 7 min period of the test. For the two handling parameters the behavioural response was scored on a scale of l-5 (Lawrence et al.. 1991). A one-way analysis of variance (Genstat V, Lawes Agricultural Trust, 1989) was carried out to examine the effect of housing in either barren or enriched environments for each of the behavioural parameters of the handling and open field tests. Likewise for the six behavioural parameters used in measuring the reaction to the change of environment, a one-way analysis of variance (Genstat V, 1989) was performed across the four treatments: gilts from barren rearing accommodation to an enriched farrowing environment; gilts from barren rearing accommodation to a barren farrowing environment; gilts from enriched rearing accommodation to a barren farrowing environment; gilts from enriched rearing accommodation to an enriched farrowing environment. Student’s t-test was used to determine whether two particular treatment means with equal variance were significantly different. Pearson’s correlation was used to examine the relationship between the behaviour of the gilts in each of the three tests.
3. Results Only the significant effects of treatment given in the methods section. 3. I. Open$eld
are given below. The units for parameters
are
test
Seven parameters revealed differences between the behaviour of gilts housed in enriched and barren environments since birth. Gilts which were housed in barren environments visited more novel squares than their enriched counterparts (B 10.6, E 8.9, SEM 0.44, P < 0.05). These gilts from barren environments spent longer periods in (B 53.5, E 35.1, SEM 5.78, PCO.05) and visited Squares 4, 10 and 11 more frequently (B 4.7, E 3.2, SEM 0.51, P < 0.05) than those gilts which were housed in enriched environments. A similar pattern was observed for the time spent in and frequency of visits to Squares 6,7 and 8. Gilts from barren environments spent more time in these squares (B 10.3, E 4.6, SEM 1.93, P < 0.05) and visited them more frequently (B 1.8, E 0.7, SEM 0.26, P < 0.01). In addition gilts from barren housing visited Squares 5, 9 and 12 approximately twice as often as gilts from enriched housing (B 3.07, E 1.6, SEM 0.36, P < 0.01). Gilts from enriched housing tended to visit squares less frequently and thus spent more time in various combinations of squares. Gilts from enriched environments vocalized twice as often as their counterparts from barren housing (B 32.4, E 69.5, SEM 10.46, P
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Animal Behaviour Science 46 (I995) 57-65
3.3. Change of environment Four of the six behavioural categories revealed differences between treatments. Both the gilts that were moved from enriched housing to barren farrowing accommodation (EB) and those that experienced the opposite crossover (BE) spent longer in what was categorized as active behaviour than their counterparts that were moved into farrowing accommodation similar to the environments in which they had been reared (EE and BB) (BB 2%“, BE 28b, EB 27b, EE 7”, SEM 5.1,P
with
3.5. Correlation of the behavioural parameters after a change of environment The time spent in active behaviour was correlated positively with the frequency of vocalizations (r= 0.502, P < 0.01). A negative correlation was found between the time spent doing nothing and the time spent lying down (r = - 0.786, P < 0.01) . 3.6. Performance There were no significant treatment effects on any of the production parameters measured at any of the stages of development (number born alive per litter: BB 11.4, EB 10.8, EE 11.2, BE 10.8, SEM 1.98, NS; birth weight (kg): BB 1.59, EB 1.64, EE 1.76, BE 1.59, SEM 0.077, NS; 6 week weight (kg): BB 15.6, EB 15.0, EE 16.7, BE 15.7, SEM 0.71, NS) . There was a tendency for gilts which had experienced a change of environment from barren to enriched housing prior to farrowing to kill more of their piglets through crushing than dams which farrowed in an environment similar to the one they were in during gestation (BB 4%, EB O%, EE 4%, BE 1 l%, SEM 3.4, NS) . Gilts which experienced the opposite crossover from enriched housing to barren farrowing accommodation savaged more piglets than gilts in any other treatment (BB 4%, EB 14%, EE 0%, BE O%, SEM 2.6, P < 0.05).
V.E. Beattie et al. /Applied
Animal Behaviour Science 46 (1995) 57-65
63
4. Discussion 4.1. Open$eld
test
The frequency of visits to squares is a measure of locomotory activity (Verga and Carenzi, 1983). Therefore gilts that had been housed in barren environments performed more locomotory behaviour. Previous work has shown that gilts which had been confined in stalls walked further in a test arena than gilts from group housing or from dirt lots (Taylor et al., 1984; Taylor and Friend, 1987). This greater amount of locomotory behaviour performed by gilts from confined barren environments may point to a motivation to perform locomotory behaviour which is thwarted in stalls (Taylor and Friend, 1987). Frequency of vocalization was greater by gilts from enriched environments than by gilts from barren housing. Vocalization by pigs has been associated with an aggressive resistant behavioural response (Hessing et al., 1993). This form of behavioural response reflects a more active coping style in comparison with a non-aggressive-non-resistantresponse which reflects a passive coping strategy. 4.2. Handling test Pigs from enriched environments were significantly harder to drive. This is contrary to work by Hunter et al. ( 1994) who found that pigs from straw based systems were easier to handle than those from fully slatted floored housing. Supporting this, Grandin (1993) claimed that there is an interaction among factors such as stimulation, flooring and genetic type which influences driveability of pigs. However it has been demonstrated that pigs which experience human contact and gentle handling show less fear of humans (Hemsworth et al., 1987) and are more difficult to drive (Grandin, 1987). The gilts from enriched housing in this study had non-aversive human contact every day during general maintenance. Through this these gilts may have learnt that their behaviour had consequences thus developing an active behavioural response to being driven. 4.3. Change of environment Gilts that experienced a change of environment prior to farrowing irrespective of the direction of that change, i.e. barren to enriched (BE) or enriched to barren (EB) performed more active behaviour and vocalized more frequently. In addition BE gilts eliminated more frequently. These behavioural parameters may well indicate that these gilts were stressed by the transitions they had undergone (Verga and Carenzi, 1983). Although gilts in both EE and BE treatments were in enriched farrowing accommodation, only EE gilts performed exploratory behaviour. As the pig is an exploratory animal (Van Putten, 1979; Wood-Gush et al.. 1983) gilts coming from barren environments to a new pen with fresh substrate would have been expected to explore. Instead BE gilts spent their time involved in active behaviour. This behaviour took the form of walking round the perimeter of the pen with head raised and was accompanied by vocalization. Such behaviour may indicate that the gilts were distressed.
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4.4 Correlation environment
of the parameters
Animal Behaviour Science 46 (1995) 57-65
of the openjeld
test with the parameters
of change of
The only behavioural characteristic which showed permanency was frequency of vocalization. Frequency of vocalization in the open field test correlated positively with frequency of vocalization after the change of environment. Characteristics which are stable over time are the fundamental basis of what psychologists label personality (Goldsmith, 1983). Varley and Stedman (1993) adopted this term when they proposed that female pigs express individual personalities. They went further, claiming that personality type in pigs was the result of the pig’s experiences early in life combined with the influence of the physical environment. In the present work gilts from enriched environments vocalized more than gilts from barren environments in the open field test. If frequency of vocalizing is a stable characteristic, hence part of the gilt’s personality, then this work supports the proposal of Varley and Stedman ( 1993) that physical environment during rearing does influence the development of personality. 4.5. Pelformance In agreement with Varley and Stedman (1993) gilts which experience a change of environment prior to farrowing, either from barren to enriched (BE) or from enriched to barren (EB) , killed more of their offspring through savaging or crushing than those which farrowed in an environment similar to the environment they were housed in during pregnancy (i.e. BB and EE) . The average birth weight of the piglets of gilts which experienced a transition and those which did not was similar; thus it cannot be argued that the piglets of BE and EB gilts were weaker and more likely to be savaged. Therefore it would appear that piglet mortality during the lactation period was due to differences in mothering behaviour. This difference in mothering behaviour may have been caused by stress due to the change of environment. However, an alternative explanation may be proposed. Early life experience has been shown to affect later behaviour of fattening pigs (Schouten, 1991; Beattie et al., 1993) and the behaviour of gilts at their first parturition (Olsson et al., 1991). Therefore the behaviour of gilts at farrowing and during lactation which experienced a crossover may have been influenced by their own early environmental experience and thus was inappropriate for their present housing environment. The proposal of Varley and Stedman ( 1993) that physical environment determines personality suggests that the current move towards loose housing gilts and sows in the gestation period may be creating dams with different personalities, the effects of this not being realized until farrowing.
5. Conclusions ( 1) Gilts’ past behavioural experiences affected their initial reaction to a novel situation. (2) Gilts reared in enriched environments were more difficult to handle than gilts reared in barren environments. This may be the result of the development of a more active coping strategy.
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Animal Behaviour Science 46 (1995) 57-65
(3) Changing the environment of the dam from loose housing to confinement can increase mortality of piglets through savaging.
65
at farrowing
Acknowledgement V.E. Beattie was sponsored by the Department
of Agriculture
for Northern Ireland.
References Appleby, M.C., 1984. Factors affecting floor laying by domestic hens: a review. Wld. Poult. Sci. J., 40: 241-247. Beattie, V.E., Sneddon, LA. and Walker, N., 1993. Behaviour and productivity of the domestic pig in barren and enriched environments. Livestock Environment IV. Fourth International Symposium. American Society of Agricultural Engineers, Coventry, pp. 43-50. Goldsmith, H.H., 1983. Genetic influences on personality from infancy to adulthood. Child Dev., 54.331-335. Grandin, T.M.S., 1987. Animal handling. Food Anim. Pratt., 3: 323-338. Grandin, T.M.S., 1993. Environmental and genetic factors which contribute to handling problems at pork slaughter plants. Livestock Environment IV, American Society of Agricultural Engineers, Coventry, pp. 64-68. Hemsworth, P.H., Bamett, J.L. and Hansen, C., 1987. The influence of inconsistent handling by humans on the behaviour, growth and corticosteroids of young pigs. Appl. Anim. Behav. Sci., 17.245-252. Hessing, M.J.C., Hagels& A.M., Van Beck, J.A.M., Wiepkema, P.R., Schouten. W.G.P. and Krulow, R., 1993. Individual behavioural characteristics in pigs. Appl. Anim. Behav. Sci., 37: 285-295. Hunter, E.J., Riches, H., Guise, H.J. and Jones, T., 1994. An analysis of farm effects on behaviour of pigs in lairage. Project report for the Humane Slaughter Association. Lawrence, A.B., Terlouw, E.M.C. and Illius, A.W., 1991. Individual differences in behavioural responses of pigs exposed to non-social and social challenges. Appl. Anim. Behav. Sci., 30: 73-86. Maier, S.F. and Seligman, M.E., 1976. Learned helplessness: theory and evidence. J. Exp. Psychol: Genet., 105: 346. Olsson, A.C., Rantzer, D., Andersson, M. and Svendsen, J., 1991. The effects of different rearing conditions in pigs during the first few weeks of life on mother-offspring behaviour. Pig News Info., 12: 71. Roff, M.F., 1974. Childhood antecedents of adult neurosis, severe bad conduct, and psychological health. In: D.F. Ricks, A. Thomas and M. Roff (Editors), Life History Research in Psychopathology. University of Minnesota Press, Minneapolis. Schouten, W.G.P., 1991. Effect of rearing on subsequent performance of pigs. Pig News Info., 12: 245-247. Simonsen, H.B., 1992. Effect of early rearing environment and tail docking on later behaviour and production in fattening pigs. Am. Sot. Anim. Sci., 70 (1): 158 (abstract). Stedman, R.C. and Varley, M.A., 1991. The assessment of sow personality and its effect on reproduction and endocrine status. Anim. Prod., 52: 576. Taylor, L. and Friend, T.H., 1987. Effect of housing on open field test behaviour of gestating gilts. Appl. Anim. Behav. Sci., 17:‘83-93. Taylor, L., Friend, T.H. and Glover, J., 1984. Effect of housing on open field test behaviour of gestating gilts. Proc. Am. Sot. Anim. Sci., 15 (abstract) Van Putten, G., 1979. Ever been close to a nosey pig? Appl. Anim. Ethol., 5: 298. Varley, M.A. and Stedman, R.C., 1993. The influence of early life environment on personality development and reproduction in multiparous sows. Anim. Prod., 56: 422. Verga, M. and Carenzi, C. 1983. Behavioural test to quantify adaptation in domestic animals. In: D. Smidt (Editor), Indicators Relevant to Farm Animal Welfare. Martinus Nijhoff, Boston, pp. 97-108. Wood-Gush, D.G.M. and Beilharz, R.G., 1983. The enrichment of a bare environment for animals in confined conditions. Appl. Anim. Ethel., 10: 107-l 10. Wood-Gush, D.G.M., Stolba, A. and Miller, C., 1983. Exploration in farm animals and animal husbandry. In: J. Archer and L.I.A. Birke (Editors), Exploration in Farm Animals and Humans. Van Nostrand Reinhold UK, pp. 198-209.
Applied Animal Behaviour
Science46 ( 1995) 5745
Effect of rearing environment and change of environment on the behaviour of gilts V.E. Beattie a**, N. Walker a, I.A. Sneddon b aAgricultural Research Institute of Northern Ireland, Hillsborough, Co. Down, ET26 6DR. UK b School of Psychology, The Queen’s University of Belfast, Belfast, ET7 INN, UK Accepted 6 July 1995
Abstract
The effect of previous experience on the behaviour of gilts was investigated. Twenty gilts were reared, from birth to farrowing, in an enriched environment and 20 in a barren environment. Six weeks prior to the expected date of parturition the gilts underwent a handling test and an open field test. A few days prior to parturition the gilts were moved into farrowing accommodation. There were two farrowing environments, barren and enriched, and, using a crossover design, gilts were moved either to a similar environment to that which they had previously experienced, i.e. barren to barren (BB) or enriched to enriched (EE) or to a different environment, i.e. barren to enriched (BE) or enriched to barren (EB). Gilts from enriched environments were more difficult to drive, scored on a scale of l5 (B 1.2, E 1.8, SEM 0.18, P < 0.05) and vocalized more frequently in the 7 min test period (B 32.4, E 69.5, SEM 10.46, P <0.05) than gilts from barren environments while the latter gilts performed more locomotory behaviour in the open field test than their counterparts from enriched environments (B 10.6, E 8.9, SEM 0.44, P < 0.05). Gilts which experienced a change of environment at parturition exhibited more active behaviour than gilts which were moved to farrowing accommodation similar to the housing in which they were reared (BB 2%“, BE 28b, EE 7”, EB 27b, SEM 5.1, P < 0.01). The influence of the environment in determining pig behaviour is discussed with reference to the effects of past experience. Keywords: Pigs; Behaviour;
Past experience
1. Introduction
Ttte early experience of humans affects their cognitive, social and emotional development. Both physical and social influences of early environment are known to have an effect on * Corresponding 0168-1591/95/%09.50 SDI0168-1591(95)
author. Tel: Hillsborough
+44-1846-682484;
Fax: +44-1846689594.
0 1995 Elsevier Science B.V. All rights reserved
58
V.E. Beattie et al. /Applied Animal Behviour
Science 46 (1995) 5765
the subsequent behaviour of humans (Roff, 1974). This also has been shown to be true in many species of animals. For example, Appleby ( 1984) found that chicks reared in deep litter housing with no perches, when given perches at a later stage, neither knew nor could learn how to perch. Wood-Gush and Beilharz (1983) revealed that the behaviour of pigs can be determined by their early life experience. They found that pigs reared in a bare cage when given earth in a trough did not use it as much as pigs that had always had access to it. Behaviours influenced by the environment in early life are retained throughout the life of the growing pig. For example high levels of social behaviour developed by piglets in barren farrowing pens have been shown to remain even if the environment is changed (Schouten, 1991; Simonsen, 1992: Beattie et al., 1993). This study investigated whether housing environment affected behaviour of gilts in mid-gestation, at approximately 8 months of age and a few days prior to farrowing at approximately 8 months of age.
2. Animals, materials and method This study was based on a four treatment crossover design. Gilts were reared in either a barren (B) or enriched (E) environment and then farrowed in either the same or opposite environments. Their behaviour was recorded during three tests or events. Eleven Large White X Landrace multiparous sows were selected as dams for the gilts in this study. Five days prior to their expected date of parturition they were moved into fat-rowing crates (2.6 X 1.6 m*). Five of these sows and their litters remained in this environment throughout the 6 week suckling period. The other six sows with their litters were moved to large, straw bedded pens (3.6 X 2.2 m*) 3 days post partum, where they were housed for the remainder of the 6 week lactation. In both environments, the male pigs were weaned at 4 weeks of age to leave only the female piglets suckling the sow. Twenty gilts from the six enriched litters were weaned at 6 weeks of age, mixed and moved to a large enriched pen. This pen measured 10.3 X 4 m* with a kennel area (2.5 X 4 m’) at one end which served as a lying area and running along opposite sides of the pen two kerbed areas (3 X 1.5 m*) each containing approximately 5 cm depth of peat. Straw was accessible from two racks and feed was available ad libitum from six single space feeders (Verba Wet Feeder, L. Verbakel B.V.). When the gilts were 165-170 days old a mature boar was penned next to their pen but the housing did not allow visual or physical contact with the boar. The gilts remained in this enriched pen through puberty and mating until just prior to parturition. The 20 gilts reared in the barren fart-owing crate house were also weaned at 6 weeks of age, mixed and moved into a barren rearing environment. This consisted of 3.5 X 1 m* pens half of which was a kennel area. The gilts stayed in these pens until 8 weeks of age when they were divided into two groups of ten and moved into 3.5 X 1.5 m2 pens which had expanded metal floors where they remained until approximately 11 weeks of age. At this stage they were moved into fully slatted floored pens in groups of five. Boars were housed in adjoining pens separated from the gilts by barred windows, this allowed both visual and physical contact. The gilts remained in this housing until mating at approximately 200 days of age when they were housed individually in stalls where they remained until several days prior to their expected parturition date.
V.E. Beattie et al. /Applied
Animal Behaviour Science 46 (1995) 5745
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59
Fig. 1. Open field test pen.
Both environments at all stages had a day/night cycle, with full lighting between 09:OO and 17:00 h and dimmed lighting for the remainder of the time. From 10 days of age to 6 weeks of age piglets in both environments were offered a commercial creep feed. The diets offered from 6 to 12 weeks of age and from 12 weeks to mating contained 14.2 MJ digestible energy (DE) kg-’ and 13.4 MJ DE kg-‘, respectively. During pregnancy, gilts in both environments were offered daily 2.2 kg of a cereal/soya based diet supplying 13.4 MJ DE. The mean daily quantity of this diet offered during lactation was 5.5 kg. Water was continuously available in both environments and straw and peat were replenished as necessary in the enriched environment. Of the initial 20 gilts reared in each of the two environments, 16 were tested in the strange situation test. Due to lack of conception and lameness three of the enriched gilts had to be removed leaving only five enriched gilts to be moved into barren farrowing accommodation (Section 2.3). 2.1. Open jield test Six weeks prior to the expected parturition date the gilts were introduced individually to the open field test pen 9.2 X 3.0 m*. This area was divided into 12 equal rectangles, each measuring 2.3 X 1 .O m*, which were numbered in an anti-clockwise direction from 1 to 12 (Fig. 1) . Each gilt was left in the novel pen for 7 min during which all her behaviour was recorded using video. Two minutes into the test, a bucket was slowly lowered to approximately 0.5 m above the ground. The number of vocalizations and eliminations made by the gilt were recorded by direct observation throughout the test. The test pen was not cleaned out between tests; therefore, to preclude any treatment bias created by olfactory cues, the order of testing was randomized. All tests were carried out between 09:OO and 12:00 h. The video tapes were analysed to determine frequency and duration of visits to individual squares. Behavioural parameters based on the open field test developed by Stedman and
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Varley ( 1991) were used. These were as follows: number of novel squares visited, i.e. the number of squares visited by the pig that had not been visited before throughout the duration of the test; total number of squares visited throughout the duration of the test. The frequency of visits (number min- ‘) and the duration (s) of time spent in various combinations of squares were also calculated. The combinations were peripheral squares (all except 11 and 12)) central squares ( 11 and 12) and squares increasingly distant from the entrance ( 1, 2 and 3; 4, 10 and 11; 5,9 and 12; 6,7 and 8). The pig was recorded as being in a square if its head and front feet were in that square. 2.2 Handling test The responses to two handling procedures based on the work of Lawrence et al. ( 1991) were recorded during the transfer of gilts from resident pens to the test pen for the open field test The first handling test was ease of movement measured as the gilts moved individually down the corridor with Observer 1 walking behind. The ease of movement was scored subjectively using a scale from 1 to 5, the easier the movement the lower the score (Lawrence et al., 1991). Response to sudden human approach (threat) was the second human pig interaction test and as with ease of movement it was scored on a scale of l-5 (Lawrence et al., 1991). 2.3. Change of environment Five days prior to the expected date of parturition, eight gilts from the enriched housing were moved into pens (3.6 X 2.2 m2) bedded with straw and five were moved into farrowing crates. A similar crossover was carried out on the gilts from barren housing: eight were moved to crates prior to fart-owing and eight to straw bedded pens. Gilts in the enriched farrowing pens were not restrained at any time during the farrowing or preweaning period. The behaviour of each gilt was recorded for 60 s every 3 min, during the first hour after movement. Vocalizations and eliminations made by the gilts were recorded and all other behaviour was assigned to one of the following mutually exclusive and comprehensive behavioural categories derived from previous observations of sows: active behaviourwalking around the pen with head raised, neck extended, pushing against the sides of the crate or door of the pen, usually accompanied by vocalizations; do nothing-standing or sitting motionless with head in a relaxed position; lie down-lying laterally or in the recumbent position with eyes open or closed; exploratory-behaviour directed towards any substrate or the ground. The time spent in each category of behaviour is expressed as a percentage of the time observed. The frequency of vocalizations is presented as a mean frequency per minute while the frequency of eliminations is a mean frequency over the period of observation. 2.4. Performance The number of piglets born alive, birth weight and the number lain on or savaged by the dam was recorded.
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61
2.5. Statistical analysis Frequency of visits to a square or combination of squares was recorded as number of visits in 1 min. Duration was recorded as the time spent in seconds in a square or combination of squares during the 7 min period of the test. For the two handling parameters the behavioural response was scored on a scale of l-5 (Lawrence et al.. 1991). A one-way analysis of variance (Genstat V, Lawes Agricultural Trust, 1989) was carried out to examine the effect of housing in either barren or enriched environments for each of the behavioural parameters of the handling and open field tests. Likewise for the six behavioural parameters used in measuring the reaction to the change of environment, a one-way analysis of variance (Genstat V, 1989) was performed across the four treatments: gilts from barren rearing accommodation to an enriched farrowing environment; gilts from barren rearing accommodation to a barren farrowing environment; gilts from enriched rearing accommodation to a barren farrowing environment; gilts from enriched rearing accommodation to an enriched farrowing environment. Student’s t-test was used to determine whether two particular treatment means with equal variance were significantly different. Pearson’s correlation was used to examine the relationship between the behaviour of the gilts in each of the three tests.
3. Results Only the significant effects of treatment given in the methods section. 3. I. Open$eld
are given below. The units for parameters
are
test
Seven parameters revealed differences between the behaviour of gilts housed in enriched and barren environments since birth. Gilts which were housed in barren environments visited more novel squares than their enriched counterparts (B 10.6, E 8.9, SEM 0.44, P < 0.05). These gilts from barren environments spent longer periods in (B 53.5, E 35.1, SEM 5.78, PCO.05) and visited Squares 4, 10 and 11 more frequently (B 4.7, E 3.2, SEM 0.51, P < 0.05) than those gilts which were housed in enriched environments. A similar pattern was observed for the time spent in and frequency of visits to Squares 6,7 and 8. Gilts from barren environments spent more time in these squares (B 10.3, E 4.6, SEM 1.93, P < 0.05) and visited them more frequently (B 1.8, E 0.7, SEM 0.26, P < 0.01). In addition gilts from barren housing visited Squares 5, 9 and 12 approximately twice as often as gilts from enriched housing (B 3.07, E 1.6, SEM 0.36, P < 0.01). Gilts from enriched housing tended to visit squares less frequently and thus spent more time in various combinations of squares. Gilts from enriched environments vocalized twice as often as their counterparts from barren housing (B 32.4, E 69.5, SEM 10.46, P
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3.3. Change of environment Four of the six behavioural categories revealed differences between treatments. Both the gilts that were moved from enriched housing to barren farrowing accommodation (EB) and those that experienced the opposite crossover (BE) spent longer in what was categorized as active behaviour than their counterparts that were moved into farrowing accommodation similar to the environments in which they had been reared (EE and BB) (BB 2%“, BE 28b, EB 27b, EE 7”, SEM 5.1,P
with
3.5. Correlation of the behavioural parameters after a change of environment The time spent in active behaviour was correlated positively with the frequency of vocalizations (r= 0.502, P < 0.01). A negative correlation was found between the time spent doing nothing and the time spent lying down (r = - 0.786, P < 0.01) . 3.6. Performance There were no significant treatment effects on any of the production parameters measured at any of the stages of development (number born alive per litter: BB 11.4, EB 10.8, EE 11.2, BE 10.8, SEM 1.98, NS; birth weight (kg): BB 1.59, EB 1.64, EE 1.76, BE 1.59, SEM 0.077, NS; 6 week weight (kg): BB 15.6, EB 15.0, EE 16.7, BE 15.7, SEM 0.71, NS) . There was a tendency for gilts which had experienced a change of environment from barren to enriched housing prior to farrowing to kill more of their piglets through crushing than dams which farrowed in an environment similar to the one they were in during gestation (BB 4%, EB O%, EE 4%, BE 1 l%, SEM 3.4, NS) . Gilts which experienced the opposite crossover from enriched housing to barren farrowing accommodation savaged more piglets than gilts in any other treatment (BB 4%, EB 14%, EE 0%, BE O%, SEM 2.6, P < 0.05).
V.E. Beattie et al. /Applied
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63
4. Discussion 4.1. Open$eld
test
The frequency of visits to squares is a measure of locomotory activity (Verga and Carenzi, 1983). Therefore gilts that had been housed in barren environments performed more locomotory behaviour. Previous work has shown that gilts which had been confined in stalls walked further in a test arena than gilts from group housing or from dirt lots (Taylor et al., 1984; Taylor and Friend, 1987). This greater amount of locomotory behaviour performed by gilts from confined barren environments may point to a motivation to perform locomotory behaviour which is thwarted in stalls (Taylor and Friend, 1987). Frequency of vocalization was greater by gilts from enriched environments than by gilts from barren housing. Vocalization by pigs has been associated with an aggressive resistant behavioural response (Hessing et al., 1993). This form of behavioural response reflects a more active coping style in comparison with a non-aggressive-non-resistantresponse which reflects a passive coping strategy. 4.2. Handling test Pigs from enriched environments were significantly harder to drive. This is contrary to work by Hunter et al. ( 1994) who found that pigs from straw based systems were easier to handle than those from fully slatted floored housing. Supporting this, Grandin (1993) claimed that there is an interaction among factors such as stimulation, flooring and genetic type which influences driveability of pigs. However it has been demonstrated that pigs which experience human contact and gentle handling show less fear of humans (Hemsworth et al., 1987) and are more difficult to drive (Grandin, 1987). The gilts from enriched housing in this study had non-aversive human contact every day during general maintenance. Through this these gilts may have learnt that their behaviour had consequences thus developing an active behavioural response to being driven. 4.3. Change of environment Gilts that experienced a change of environment prior to farrowing irrespective of the direction of that change, i.e. barren to enriched (BE) or enriched to barren (EB) performed more active behaviour and vocalized more frequently. In addition BE gilts eliminated more frequently. These behavioural parameters may well indicate that these gilts were stressed by the transitions they had undergone (Verga and Carenzi, 1983). Although gilts in both EE and BE treatments were in enriched farrowing accommodation, only EE gilts performed exploratory behaviour. As the pig is an exploratory animal (Van Putten, 1979; Wood-Gush et al.. 1983) gilts coming from barren environments to a new pen with fresh substrate would have been expected to explore. Instead BE gilts spent their time involved in active behaviour. This behaviour took the form of walking round the perimeter of the pen with head raised and was accompanied by vocalization. Such behaviour may indicate that the gilts were distressed.
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4.4 Correlation environment
of the parameters
Animal Behaviour Science 46 (1995) 57-65
of the openjeld
test with the parameters
of change of
The only behavioural characteristic which showed permanency was frequency of vocalization. Frequency of vocalization in the open field test correlated positively with frequency of vocalization after the change of environment. Characteristics which are stable over time are the fundamental basis of what psychologists label personality (Goldsmith, 1983). Varley and Stedman (1993) adopted this term when they proposed that female pigs express individual personalities. They went further, claiming that personality type in pigs was the result of the pig’s experiences early in life combined with the influence of the physical environment. In the present work gilts from enriched environments vocalized more than gilts from barren environments in the open field test. If frequency of vocalizing is a stable characteristic, hence part of the gilt’s personality, then this work supports the proposal of Varley and Stedman ( 1993) that physical environment during rearing does influence the development of personality. 4.5. Pelformance In agreement with Varley and Stedman (1993) gilts which experience a change of environment prior to farrowing, either from barren to enriched (BE) or from enriched to barren (EB) , killed more of their offspring through savaging or crushing than those which farrowed in an environment similar to the environment they were housed in during pregnancy (i.e. BB and EE) . The average birth weight of the piglets of gilts which experienced a transition and those which did not was similar; thus it cannot be argued that the piglets of BE and EB gilts were weaker and more likely to be savaged. Therefore it would appear that piglet mortality during the lactation period was due to differences in mothering behaviour. This difference in mothering behaviour may have been caused by stress due to the change of environment. However, an alternative explanation may be proposed. Early life experience has been shown to affect later behaviour of fattening pigs (Schouten, 1991; Beattie et al., 1993) and the behaviour of gilts at their first parturition (Olsson et al., 1991). Therefore the behaviour of gilts at farrowing and during lactation which experienced a crossover may have been influenced by their own early environmental experience and thus was inappropriate for their present housing environment. The proposal of Varley and Stedman ( 1993) that physical environment determines personality suggests that the current move towards loose housing gilts and sows in the gestation period may be creating dams with different personalities, the effects of this not being realized until farrowing.
5. Conclusions ( 1) Gilts’ past behavioural experiences affected their initial reaction to a novel situation. (2) Gilts reared in enriched environments were more difficult to handle than gilts reared in barren environments. This may be the result of the development of a more active coping strategy.
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(3) Changing the environment of the dam from loose housing to confinement can increase mortality of piglets through savaging.
65
at farrowing
Acknowledgement V.E. Beattie was sponsored by the Department
of Agriculture
for Northern Ireland.
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