The Effect of an Irregular Feeding Schedule on Equine Behavior

Abstract

We used eight horses 1 to 12 years old to investigate the influence of irregular feeding times on the behavior. The animals were housed in individual boxes, fed with hay ad libitum and barley-oat mixture at three set times; 05:00 (earlier feeding) on Thursdays, 07:00 (delayed feeding) on Saturdays and 06:00 (regular feeding) on other weekdays. Direct observations took place in 10 continuous weeks; they started 1 h prior to feeding and lasted for 2 h. Long-term behaviors (i.e. hay and concentrate consumption, resting) were recorded every 5 min, short-term behaviors (i.e. kicking, pawing the ground, comfort behavior, taking a look toward the door) were recorded continuously. Compared to the regular feeding time, horses spent less time consuming hay, more time resting and less often took a look toward the door during the earlier feeding, whereas during the delayed feeding horses more often performed pawing the ground, kicking, comfort behavior, and took a look toward the door (p < .05). Our results indicate that deviations from the regular feeding schedule affected the behavior of horses and compromised their temporal predictability.

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Journal of Applied Animal Welfare Science
ISSN: 1088-8705 (Print) 1532-7604 (Online) Journal homepage: https://www.tandfonline.com/loi/haaw20
The Effect of an Irregular Feeding Schedule on
Equine Behavior
Manja Zupan, Ivan Štuhec & Dušanka Jordan
To cite this article: Manja Zupan, Ivan Štuhec & Dušanka Jordan (2020) The Effect of an Irregular
Feeding Schedule on Equine Behavior, Journal of Applied Animal Welfare Science, 23:2, 156-163,
DOI: 10.1080/10888705.2019.1663734
To link to this article: https://doi.org/10.1080/10888705.2019.1663734
Published online: 07 Sep 2019.
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COMPANION ANIMAL
The Effect of an Irregular Feeding Schedule on Equine Behavior
Manja Zupan
a
, Ivan Štuhec
a
, and Dušanka Jordan
a
a
Biotechnical Faculty, Department of Animal Science, University of Ljubljana, Domžale, Slovenia
ABSTRACT
We used eight horses 1 to 12 years old to investigate the influence of
irregular feeding times on the behavior. The animals were housed in
individual boxes, fed with hay ad libitum and barley-oat mixture at three
set times; 05:00 (earlier feeding) on Thursdays, 07:00 (delayed feeding) on
Saturdays and 06:00 (regular feeding) on other weekdays. Direct observa-
tions took place in 10 continuous weeks; they started 1 h prior to feeding
and lasted for 2 h. Long-term behaviors (i.e. hay and concentrate consump-
tion, resting) were recorded every 5 min, short-term behaviors (i.e. kicking,
pawing the ground, comfort behavior, taking a look toward the door) were
recorded continuously. Compared to the regular feeding time, horses spent
less time consuming hay, more time resting and less often took a look
toward the door during the earlier feeding, whereas during the delayed
feeding horses more often performed pawing the ground, kicking, comfort
behavior, and took a look toward the door (p< .05). Our results indicate
that deviations from the regular feeding schedule affected the behavior of
horses and compromised their temporal predictability.
KEYWORDS
Horse; behavior;
anticipation; predictability;
feeding
Introduction
A temporal predictability of management routines, such as feeding, has been found to enable
animals to better cope with their environment (Johannesson & Ladewig, 2000) while unpredictable
and/or uncontrollable situations are often perceived as stressors by animals (Koolhaas et al., 2011). If
an animal is not able to foresee or control negative as well as positive events, it may perceive such
a situation as stressful. This leads to behavioral and physiological stress response indicating that
animal welfare is compromised (Wiepkema & Koolhaas, 1993). However, the results of studies,
which focus on the effect of an unpredictable feeding time on animal behavior and welfare, are
rather inconsistent or even contradictory; some of the studies suggested unpredictable feeding time
to reduce abnormal behaviors (Bloomsmith & Lambeth, 1995) and prevent stress (Waitt &
Buchanan-Smith, 2001), while the others emphasized the importance of predictable feeding time
to reduce aggression (Carlstead, 1986; Jones, Noble, Damsgard, & Pearce, 2012) and stress (Gottlieb,
Coleman, & McCowan, 2013; Ulyan et al., 2006). Furthermore, the majority of studies has been done
in captive wild animals, e. g. chimpanzees (Bloomsmith & Lambeth, 1995), stump-tailed (Waitt &
Buchanan-Smith, 2001) and rhesus macaques (Gottlieb et al., 2013), fish (Jones et al., 2012) and only
seldom in farm animals (Carlstead, 1986; Johannesson & Ladewig, 2000), including horses.
In horses, it is highly recommended to avoid sudden or large changes in their daily routine,
especially in feeding, turning out and exercise, which are the most positive events in horses’daily
routine (Mills & Clarke, 2007). Regarding feeding practice, it is well-known that rapid and major
changes in diet (volume or composition) and feeding occasions are related to digestive disorders
(Davidson & Harris, 2007; Tinker et al., 1997) as well as stereotypies’incidence (Cooper &
CONTACT Manja Zupan manja.zupan@bf.uni-lj.si Biotechnical Faculty, Department of Animal Science, University of
Ljubljana, Groblje 3, Domžale SI-1230, Slovenia
© 2019 Informa UK Limited, trading as Taylor & Francis Group
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE
2020, VOL. 23, NO. 2, 156–163
https://doi.org/10.1080/10888705.2019.1663734

McGreevy, 2007). However, almost nothing is known about sudden changes in feeding time,
especially about their influence on horses’behavior and welfare, although in leisure horses or horses
used for sport and work, it is often difficult to keep management routines regular due to different
factors that influence owner’s spare time, work or competitions. Ninomiya, Kusunose, Sato, Terada,
and Sugawara (2004) provided some evidence about the delayed feeding time suggesting that it may
increase the duration of hay-eating and bedding investigation, the latter interpreted as frustration
due to suppressed consummatory behavior. Cooper and McGreevy (2007) suggested that predictable
feeding schedules, when horses are being fed approximately at the same time for years, may lead to
stereotypies. Bezdekova, Jahn, and Vyskocil (2008), on the contrary, found no association between
feeding regularity and horse’s gastric health.
A scarcity of studies, which researched the effect of unpredictable feeding times on the behavior of
horses and welfare and inconsistency of their results, justifies further investigation. Additionally, to our
knowledge, there has been no study looking at the effect of earlier feeding time on the behavior of horses
and welfare. Therefore, we conducted a study with eight horses housed in single stalls, a predominant
form of housing in different countries (Korries, 2003; Søndergaard & Christensen, 2002;Starc,2016), to
investigate whether earlier or delayed feeding time influences the behavior of horses.
Material and methods
Animals, housing and management
The experiment was carried out in a private horse center in Slovenia. The subjects were eight horses in
the range of 1 to 12 years of age. Four of them were trotter horses (Slovenian trotter) and the other four
were riding horses (three of Slovenian warm-blood horse, one of Arabian thoroughbred horse). The
horses were either born and raised on the mentioned horse center or purchased from other horse
centers in Slovenia. The group consisted of five mares and three geldings. The horses were housed in
a stable with individual straw-bedded boxes (3.5 m × 4.0 m). The bottom part of the partitions dividing
boxes was made of solid wooden panels, while the top part was made of vertical lattice bars. Each day,
trotter horses had an individual training for 1 h, while riding horses were periodically used for field
riding. Horses were fed indoors once a day, usually at 06:00, when they received their morning meal,
which represented the major component of their diet. Horses were always fed by the same caretaker and
in the same turn. They were turned out to the pasture after feeding at around 08:00.
At feeding, which took a few minutes, horses received barley-oat mixture and soon after also fresh
hay. Hay was offered ad libitum, while the amount and the composition of the concentrate were
adjusted to the horse’s weight, size and daily workload. During the study, the horses received on average
1.6 kg of concentrate per individual in a feed trough (dimension of a hole above it 47 cm × 41 cm ×
16 cm) placed in the left front corner of the box at the height of 55 cm. Hay was placed on the ground in
the corner under the feed trough. Available roughage thus consisted of both, straw and hay, and enabled
animals to forage and explore. Water was available ad libitum from an automatic water supplier in the
back right corner. Each animal had access to a mineral lick. Dirty litter was removed when necessary in
order to keep the box as clean as possible and fresh straw was added. For the purpose of the study,
animals were fed at three different times, each feeding time representing a treatment: as usual at 06:00, 1
h earlier (at 05:00) and 1 h later (at 07:00). The usual feeding time was considered as a regular treatment,
feeding at 05:00 as earlier and feeding at 07:00 as delayed treatment (Figure 1). Feeding times at 05:00
and 07:00 were considered as irregular feeding times. The horses were fed at 05:00 on Thursdays, at
07:00 on Saturdays and at 06:00 on other days within the week.
Behavioral observations
The behavior of horses was recorded directly during summer months by one observer for 10 weeks,
3days a week, Tuesdays, Thursdays and Saturdays. On each of the observation days, the recordings
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE 157

lasted two continuous hours, starting 1 h before feeding and ending 1 h after feed delivery (Figure 1).
In order to prevent the observer’s influence on horse behavior, the observer watched the animals
through a window from the outside the stable. This position of the observer enabled simultaneous
recording of behavior of all eight horses. The ethogram used for observations is presented in Table 1.
The long-term behaviors were recorded every 5 min, which accounted to 24 intervals per 2 h of
observation period. In the results section, these behaviors are presented as a percentage of observa-
tions spent for a particular behavior per observation period and animal. The short-term behaviors
were recorded continuously and are presented as a frequency per observation period and animal.
Statistical analysis
The statistical data analysis was conducted using GLIMMIX procedure in the SAS/STAT statistical
program package (SAS/STAT, 2011). For the purpose of the analysis, some of the behaviors were
aggregated: comfort behavior included stretching and auto-grooming, kicking included kicking with
04:00 05:00 06:00 07:00 08:00 Hour
Treatment (feeding time):
Earlier (05:00)
Regular (06:00)
Delayed (07:00)
Tur nin
g
out to
p
asture
Figure 1. Observation period and treatments regarding the feeding time.
Table 1. Behaviors recorded during observations and their definitions.
Behavior Definition
Concentrate consumption
L
Head positioned inside the feed trough and taking barley-oat mixture diet into mouth.
Hay consumption
L
Taking hay into mouth with a lowered head and neck and making mouth movements under or in
front of a feed trough.
Standing
L
Standing with a) normal head position without target directed head movements and without one
hind leg resting (normal standing) or b) with a head positioned high, usually with a target directed
head movements, ears pointing in the direction in which the horse is looking with its eyelids fully
opened (standing alert) or c) with lowered head, one hind leg in a rest position and eyelids half
open or closed (standing at rest).
Lying
L
Lying slightly on the side of its chest with one foreleg and one hind leg underneath the body.
Manipulation with
a drinking bowl
L
Oral activities with a drinking bowl but without drinking or drinking little.
Manipulation with a feed
trough
L
Oral activities with an empty feed trough.
Drinking
S
Mouth positioned inside the drinking bowl with head still and taking water into mouth and
swallowing it.
Neighing
S
Vocalization with the long, high-pitched sound.
Kicking with a fore leg
S
To strike with a front leg at the ground or forwards.
Kicking with a hind leg
S
To strike with a hind leg at the ground or backwards.
Circling
S
Circular box walking.
Scraping the teeth on the
surface
S
To pull back its lips and rub a wooden surface of the stall partition forcefully with the teeth.
Pawing the ground
S
To drag with a front leg along the ground.
Stretching
S
Flexion at the throat, arching of the neck, straightening of the back, elevation and movement of
the tail and full extension of the hind limbs.
Auto-grooming
S
Different forms of body care such as scratching, rubbing, shaking and licking.
Taking a look toward the
door
S
A look at the stall door with attention, with the head heightened and turned toward the door.
L–Long-term activity, S –short-term activity
158 M. ZUPAN ET AL.

foreleg or hind leg, resting included standing and lying. The following statistical models were chosen:
a) Poisson regression model for the analysis of the following short-term behaviors: comfort behavior,
taking a look toward the door, kicking and pawing the ground, and b) Negative Binomial regression
model for the analysis of the following long-term behaviors: concentrate consumption, hay con-
sumption and resting. All the models included the factor of treatment (n = 3; earlier, regular and
delayed) and animal nested within the treatment (n = 8) as random factor. Horses performed also
drinking, neighing, circling and scraping the teeth on the surface, but at a very low frequency that
accounted for around 90% of zeros per individual behavior in the observation period. The analysis of
these observed behaviors could not be performed due to insufficient data variability. The manipula-
tion with a drinking bowl and a feed trough accounted to 0.78% and 1.23% of the total observed
time, respectively, and thus we considered them not to be used for the analysis due to a low
frequency. The models for the majority of behaviors did not converge when the effect week was
included; hence the models only included treatment as a fixed effect.
Results
Irregular feeding of horses affected both the long-term and short-term behaviors. It had a significant
influence on the time the horses spent consuming hay (F = 7.93; p< .01) and resting (F = 9.26; p<.01),
but it did not influence the time horses spent consuming concentrate (F = 0.32; p> .10; Figure 2).
When fed earlier, horses spent less time consuming hay and rested longer compared to when fed at the
regular time or 1 h later. The feeding time also significantly influenced the frequency of comfort
behavior (F = 7.65; p< .01; Figure 3), taking a look toward the door (F = 129.21; p< .0001), kicking (F
=3.91;p< .05) and pawing the ground (F = 5.99; p< .01). When fed earlier, horses took a look toward
the door significantly less often than when fed at the regular time. When fed later, horses significantly
more often performed comfort behavior, took a look toward the door, pawed the ground and kicked
compared to when fed at the regular or earlier feeding time.
Discussion
The main finding of our study is that the earlier and the delayed feeding times generated
different expressions of observed behaviors in stabled horses, indicating that horses knew at
what time they got feed. Feeding is one of the most positive event in captive animals’daily
routine (Bassett & Buchanan-Smith, 2007; Carlstead, 1986) and if performed at a regular time
0
10
20
30
40
50
60
70
Concentrate
consumption
Hay consumption Resting
Means and SE
Lon
g
-term behavior
Earlier
Regular
Delayed
Treatment:
a b b a b b
Figure 2. The influence of feeding time on the proportion of time (%) of long-term behaviors presented as means and standard
errors (SE) of the 2 h of observations per treatment. Significant differences within individual behavior are indicated by different
letters (a, b).
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE 159

each day animals learn to predict the time of feeding due to their endogenous clock (Mistlberger,
1994). It is also known that signals, which always precede feeding, e.g. random sounds connected
with preparation and distribution of feed, act as conditioned stimuli and function as cues to the
oncoming feeding, enabling animals to predict the feed arrival even more precisely (Nicol, 2005;
Peters, Bleijenberg, van Dierendonck, van der Harst, & Spruijt, 2012).Similarashorsesinour
study, farm animals like pigs (Carlstead, 1986) and calves (Johannesson & Ladewig, 2000)or
captive wild animals like chimpanzees (Bloomsmith & Lambeth, 1995), rhesus macaques (Gottlieb
et al., 2013) and coyotes (Gilbert-Norton, Leaver, & Shivik, 2009), customized to predictable
feeding time, react to deviations from their regular feeding schedule or reliable feeding signals
with changes in their behavior.
Earlier feeding
When horses were fed earlier, they spent significantly less time-consuming hay compared to when
they were fed at the regular time. Since horses are trickle feeders (Davidson & Harris, 2007), we
would expect them to take advantage of the earlier feeding and spend ingesting hay at least for as
long as when fed at the regular time. However, when animals are regularly fed at the same time, they
adapt their physiology and behavior to match their daily meal (Feillet, 2010), which enable them to
prepare for feed ingestion. Therefore, our results suggest that within 2 h before regular feeding, the
physiology and behavior of a horse were not yet directed to hay consumption. This is further
supported with the significantly longer time they spent resting, when their feeding time was earlier
than usual. The horses did not expect to be fed yet and consequently did not start preparing for
feeding by waking up and being as active as they would usually do in the hours prior to the expected
feeding (Feillet, 2010). Their unpreparedness for feeding was confirmed also by a very small
frequency of taking a look toward the door which was significantly lower compared to the regular
feeding time. Our interpretation could further be strengthen if that was before the concentrate
feeding versus afterward, but unfortunately, we did not record the behaviors on hourly bases only for
the full 2-h period. Although the duration of hay consumption and resting when fed earlier indicated
that the horses were not motivated for eating prior to the regular time, the time of feeding did not
significantly influence the consumption of the barley-oats mixture. This is not surprising since the
palatable cereal-based concentrate was offered to the horses only once per day in a limited quantity
0
1
2
3
4
5
6
7
Comfort behavior Taking a look
toward the door
Pawing the
ground
Kicking
Means and SE
Short-term behavior
Earlier
Regular
Delayed
Treatment
:
a a b a b c a a b a a b
Figure 3. The influence of feeding time on the frequency of short-term behaviors presented as means and standard errors (SE) of
the 2 h of observations per treatment. Significant differences within individual behavior are indicated by different letters (a, b, c).
160 M. ZUPAN ET AL.

and it is known that the feed palatability strongly influences motivation for ingestion (Julliand,
Philippeau, Goachet, & Ralston, 2008).
Delayed feeding
The delayed feeding time did not affect any of the observed long-term behaviors compared to regular
feeding time. This contradicts the findings of Ninomiya et al. (2004) where a tendency in the
increase of hay consumption was found in the delayed feeding. A similar duration of resting at
the regular or the delayed feeding most likely indicates that our horses expected feeding at the
regular time. This argumentation is supported by Feillet (2010), who stated that animals fed
every day at the same time wake up and start to be active prior to the hour of the expected feeding.
The delayed feeding, however, significantly increased the frequency of all observed short-term
behaviors compared to the regular feeding time. An increased performance of these behaviors was
most likely an expression of the horses’pre-feeding anticipatory behavior. Also in other studies,
where animals were fed at a regular time for a longer period of time (e.g. Bassett & Buchanan-Smith,
2007; Johannesson & Ladewig, 2000; Ulyan et al., 2006), it was reported that delayed feeding resulted
in display of anticipatory behavior. Anticipatory behavior is defined as behavioral activity significant
for the period between a signal indicating the arrival of a rewarding event and the actual arrival of
the reward (Boissy et al., 2007). Receiving feed, especially concentrates, it represents one of the most
rewarding events in horses’daily routine (Mills & Clarke, 2007). In our study, horses more often
took a look toward the door, most probably because they heard familiar sounds outside the barn
announcing feeding time. They also more frequently pawed the ground and kicked, which are
features often referred to as behavioral patterns of anticipatory behavior in horses (Cooper &
McGreevy, 2007; Peters et al., 2012). It is known that as the interval between cues to the oncoming
feeding and feed arrival progresses, the average level of anticipatory behavior increases (Balsam,
Sanchez-Castillo, Taylor, Van Volkinburg, & Ward, 2009). Our horses’response may be even more
distinct since they were awaiting the concentrate, their preferred feed (Goodwin, Davidson, & Harris,
2005), which may therefore have affected them as a supernormal stimulus (unusually potent or
intense stimulus; Mendl, 1997). Additionally, they might have also anticipated to be turned out to
the pasture, a management routine that the horses were used to. Especially by kicking the door or the
wall, horses seek for an attention (Broom & Fraser, 2015; Cooper & McGreevy, 2007) for they must
have previously learned that such a behavior results in receiving a reward, e.g. being fed earlier
(Cooper & McGreevy, 2007).
Our horses more often demonstrated comfort behavior when feeding was delayed, which may
be interpreted as a sign of anticipation or frustration. Increased comfort behavior associated with
an anticipation of positive event was reported in rats (van der Harst, Baars, & Spruijt, 2003), laying
hens(Zimmerman,Buijs,Bolhuis,&Keeling,2011) and calves (Johannesson & Ladewig, 2000).
However, numerous studies reported increased grooming in situations causing anxiety (Castles &
Whiten, 1998; Molesti & Majolo, 2013) or frustration (Waitt & Buchanan-Smith, 2001).
Frustration is a motivational state that occurs when animal is thwarted or blocked in its attempts
to achieve a goal (Hurnik, Webster, & Siegel, 1995;Millsetal.,2010) and is a sign of poor animal
welfare (Broom & Johnson, 1993;Nicol,2011). Additionally, pawing the ground has been reported
to occur when horses are frustrated, mainly in relation to obtaining feed (Broom & Fraser, 2015;
Fraser, 1992;Houpt,1986;Hurniketal.,1995). There seems to be two possible explanations for
the increase in the performance of short-term behaviors because of 1-h delay in feeding: it was
either a performance of pre-feeding anticipatory behavior or a demonstration of signs of a certain
degree of frustration because the horses’expectations to be fed at the regular feeding time were not
fulfilled.
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE 161

Conclusions
The horses were used to regular feeding schedule, therefore, they reacted to deviations from it
by changes in their behavior. If they were fed earlier than expected, the horses spent less time
consuming hay and more time resting which indicate they were not ready to consume hay yet.
When they were fed later than expected, the horses showed an increase in taking a look toward
the door, kicking, pawing the ground and comfort behavior which may be an indication of
a certain degree of pre-feeding anticipation or frustration. Our results suggest that inclusion of
irregular feeding times in the feeding management cause horses to lose their temporal predict-
ability. We propose horse caretakers to maintain daily management routine as stable as
possible.
Acknowledgments
We are thankful to Tanja Zorec for the observation of horses and to Roman Vučajnk for improving the English.
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