Directory UMM :Data Elmu:jurnal:A:Applied Animal Behaviour Science:Vol70.Issue2.2000:
Applied Animal Behaviour Science 70 (2000) 115±126
Do pigs ®nd a familiar odourant attractive
in novel surroundings?
J.B. Jonesa, C.M. Wathesa,*, R.P. Whitea, R.B. Jonesb
a
Silsoe Research Institute, Wrest Park, Silsoe, Bedfordshire MK45 4HS, UK
b
Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK
Accepted 16 May 2000
Abstract
Sixty-four DurocLandrace pigs (Sus scrofa) of both sexes were reared from birth to 6 weeks of
age in either fresh air or an atmosphere containing an arti®cial odourant (Ambi-Pur). Their
behavioural responses to a novel environment (a modi®ed open ®eld) were then observed over 1 h
when the test arena contained either the familiar Ambi-Pur odourant or ammonia gas at 45 ppm.
Although members of other mammalian and avian species are attracted to familiar odours in
otherwise novel surroundings, the presence of Ambi-Pur had no effect on the pigs' readiness to
enter the novel arena from a sheltered area or on other fear-related behaviours following entry
(p>0.05). Pigs kept in fresh air from weaning until test were generally less active and spent less time
at the centre of the open ®eld if the test was carried out in an ammoniated atmosphere rather than
fresh air; this suggests that they found ammonia aversive. On the other hand, the presence of
ammonia at test accelerated approach to the centre of the open ®eld and increased the number of
entries into that area and the percentage of time spent there as well as overall activity in pigs that
had also been exposed chronically to this gas at 43 ppm from weaning until testing at 6 weeks
(p0.05, Table 2) and these data are
therefore not presented.
In general, the behaviour of the pigs that had received previous exposure to the arti®cial
odourant in the farrowing ark and holding room was not affected by its presence or absence
in the novel test room (Table 2, p>0.05 for all relevant factors). There was, however, one
exception. Pigs which had been exposed to the arti®cial odourant in Phases 1 and 2 were
generally more active (as indicated by the number of moves across a 55 grid) than
unexposed controls (Table 2, Phase 1 and 2 odourant, p0.014). This probably re¯ected a
Type 1 error because the other behavioural responses of these pigs showed no consistent
trend. Contrary to ®ndings that laboratory rodents and chickens were attracted to, and
reassured by, familiar odours presented in otherwise unfamiliar surroundings (Devor and
Schneider, 1974; Carr et al., 1979; Galef, 1981; Jones and Gentle, 1985; Burne and Rogers,
1995; Porter and Picard, 1998; Jones and Carmichael, 1999), the responses of the pigs used
here were unaffected by the presence or absence in the novel environment of an arti®cial
odourant (Ambi-Pur) with which they had been reared from birth. There are at least three
possible explanation for this ®nding. Firstly, the animals may have developed a transient
hyposmia for the components of this odourant and thereby ceased to sense it. Secondly,
although no disgust or avoidance responses to Ambi-Pur were seen in the home environment, it is conceivable that either some of its components or its overall olfactory gestalt had
aversive properties that counterbalanced the development of attraction through familiarisation. Thirdly, and perhaps more likely, the pigs may not have formed a suf®ciently strong
association between this olfactory cue and the familiar home environment, possibly
because the compounds did not occur naturally and have biological relevance.
In contrast, chronic exposure to ammonia in Phase 2 affected the behaviour of the pigs in
Phase 3 according to the presence or absence of ammonia in the open ®eld (Table 2, two
factor interaction between Phases 2 and 3 ammonia). The effects were consistent for four
behaviours, i.e. the latency to approach the centre of the open ®eld (F(1,44)4.16,
P0.047), the number of visits to the centre (F(1,44)7.81, P0.008), the time spent
there (F(1,44)4.29, P0.044), and their general activity (F(1,44)8.05, P0.007). The
results given in Table 4 indicate a general trend that if the pigs had been exposed to 43 ppm
ammonia during Phase 2, then its presence in the open ®eld at a similar concentration
(45 ppm) reduced the latency to approach the centre of the open ®eld, increased the number
of times the centre was entered and the time spent there, and increased general activity.
These ®ndings suggest that this concentration of ammonia may have represented a familiar
cue and thereby attracted and reassured these pigs. It is considered unlikely that the
increased activity observed in this situation re¯ected irritation because the pigs would not
then have been expected to approach the odour source so frequently or to spend as long near
it. Conversely, pigs that had been reared in fresh air were less active, made fewer visits to
and spent less time in the centre of the open ®eld when it contained ammonia. In other
words, they appeared to be averse to the ammoniated atmosphere. Similarly, when given a
Phases 1 and 2
(experience)
Odourant
No odourant
Odourant
No odourant
Standard error of difference
between means
Phase 3 (open field
environment)
Snout
Body
Latency to approach
centre of open
field (s)
Ammonia
No ammonia1
Ammonia1
No ammonia1
1.28
1.12
1.21
1.49
1.55
1.39
1.46
1.63
2.29
2.22
2.17
2.16
1.31
1.45
1.34
1.14
0.11
0.36
0.19
0.03
Odourant2
No odourant2
Odourant2
No odourant2
1.16
1.24
1.40
1.31
1.46
1.49
1.57
1.51
2.23
2.28
2.14
2.19
1.41
1.36
1.24
1.24
0.28
0.19
0.09
0.12
2.91
2.85
2.80
2.70
0.181
0.161
0.148
0.092
0.109
0.053
1
Emergence latency (s)
Number of times
centre of open
field entered
% Time spent at
centre of open
field
Moves across
55 grid
2.87
2.90
2.78
2.72
b
a
ab
b
f
Mean (log10) open field behaviour of pigs exposed/not exposed to an artificial odourant before test, listed according to the different environmental conditions in the
open field (absence/presence of odourant and/or 45 ppm ammonia). Letters `a' and `b' indicate differences significant at P
Do pigs ®nd a familiar odourant attractive
in novel surroundings?
J.B. Jonesa, C.M. Wathesa,*, R.P. Whitea, R.B. Jonesb
a
Silsoe Research Institute, Wrest Park, Silsoe, Bedfordshire MK45 4HS, UK
b
Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK
Accepted 16 May 2000
Abstract
Sixty-four DurocLandrace pigs (Sus scrofa) of both sexes were reared from birth to 6 weeks of
age in either fresh air or an atmosphere containing an arti®cial odourant (Ambi-Pur). Their
behavioural responses to a novel environment (a modi®ed open ®eld) were then observed over 1 h
when the test arena contained either the familiar Ambi-Pur odourant or ammonia gas at 45 ppm.
Although members of other mammalian and avian species are attracted to familiar odours in
otherwise novel surroundings, the presence of Ambi-Pur had no effect on the pigs' readiness to
enter the novel arena from a sheltered area or on other fear-related behaviours following entry
(p>0.05). Pigs kept in fresh air from weaning until test were generally less active and spent less time
at the centre of the open ®eld if the test was carried out in an ammoniated atmosphere rather than
fresh air; this suggests that they found ammonia aversive. On the other hand, the presence of
ammonia at test accelerated approach to the centre of the open ®eld and increased the number of
entries into that area and the percentage of time spent there as well as overall activity in pigs that
had also been exposed chronically to this gas at 43 ppm from weaning until testing at 6 weeks
(p0.05, Table 2) and these data are
therefore not presented.
In general, the behaviour of the pigs that had received previous exposure to the arti®cial
odourant in the farrowing ark and holding room was not affected by its presence or absence
in the novel test room (Table 2, p>0.05 for all relevant factors). There was, however, one
exception. Pigs which had been exposed to the arti®cial odourant in Phases 1 and 2 were
generally more active (as indicated by the number of moves across a 55 grid) than
unexposed controls (Table 2, Phase 1 and 2 odourant, p0.014). This probably re¯ected a
Type 1 error because the other behavioural responses of these pigs showed no consistent
trend. Contrary to ®ndings that laboratory rodents and chickens were attracted to, and
reassured by, familiar odours presented in otherwise unfamiliar surroundings (Devor and
Schneider, 1974; Carr et al., 1979; Galef, 1981; Jones and Gentle, 1985; Burne and Rogers,
1995; Porter and Picard, 1998; Jones and Carmichael, 1999), the responses of the pigs used
here were unaffected by the presence or absence in the novel environment of an arti®cial
odourant (Ambi-Pur) with which they had been reared from birth. There are at least three
possible explanation for this ®nding. Firstly, the animals may have developed a transient
hyposmia for the components of this odourant and thereby ceased to sense it. Secondly,
although no disgust or avoidance responses to Ambi-Pur were seen in the home environment, it is conceivable that either some of its components or its overall olfactory gestalt had
aversive properties that counterbalanced the development of attraction through familiarisation. Thirdly, and perhaps more likely, the pigs may not have formed a suf®ciently strong
association between this olfactory cue and the familiar home environment, possibly
because the compounds did not occur naturally and have biological relevance.
In contrast, chronic exposure to ammonia in Phase 2 affected the behaviour of the pigs in
Phase 3 according to the presence or absence of ammonia in the open ®eld (Table 2, two
factor interaction between Phases 2 and 3 ammonia). The effects were consistent for four
behaviours, i.e. the latency to approach the centre of the open ®eld (F(1,44)4.16,
P0.047), the number of visits to the centre (F(1,44)7.81, P0.008), the time spent
there (F(1,44)4.29, P0.044), and their general activity (F(1,44)8.05, P0.007). The
results given in Table 4 indicate a general trend that if the pigs had been exposed to 43 ppm
ammonia during Phase 2, then its presence in the open ®eld at a similar concentration
(45 ppm) reduced the latency to approach the centre of the open ®eld, increased the number
of times the centre was entered and the time spent there, and increased general activity.
These ®ndings suggest that this concentration of ammonia may have represented a familiar
cue and thereby attracted and reassured these pigs. It is considered unlikely that the
increased activity observed in this situation re¯ected irritation because the pigs would not
then have been expected to approach the odour source so frequently or to spend as long near
it. Conversely, pigs that had been reared in fresh air were less active, made fewer visits to
and spent less time in the centre of the open ®eld when it contained ammonia. In other
words, they appeared to be averse to the ammoniated atmosphere. Similarly, when given a
Phases 1 and 2
(experience)
Odourant
No odourant
Odourant
No odourant
Standard error of difference
between means
Phase 3 (open field
environment)
Snout
Body
Latency to approach
centre of open
field (s)
Ammonia
No ammonia1
Ammonia1
No ammonia1
1.28
1.12
1.21
1.49
1.55
1.39
1.46
1.63
2.29
2.22
2.17
2.16
1.31
1.45
1.34
1.14
0.11
0.36
0.19
0.03
Odourant2
No odourant2
Odourant2
No odourant2
1.16
1.24
1.40
1.31
1.46
1.49
1.57
1.51
2.23
2.28
2.14
2.19
1.41
1.36
1.24
1.24
0.28
0.19
0.09
0.12
2.91
2.85
2.80
2.70
0.181
0.161
0.148
0.092
0.109
0.053
1
Emergence latency (s)
Number of times
centre of open
field entered
% Time spent at
centre of open
field
Moves across
55 grid
2.87
2.90
2.78
2.72
b
a
ab
b
f
Mean (log10) open field behaviour of pigs exposed/not exposed to an artificial odourant before test, listed according to the different environmental conditions in the
open field (absence/presence of odourant and/or 45 ppm ammonia). Letters `a' and `b' indicate differences significant at P