www.elsevier.comrlocaterapplanim
Aversion learning techniques to evaluate dairy
cattle handling practices
E.A. Pajor
), J. Rushen, A.M.B. de Passille
´
Dairy and Swine Research and DeÕelopment Centre, Agriculture and Agri-Food Canada, LennoxÕille,
Quebec, Canada J1M 1Z3
Accepted 15 March 2000
Abstract
Fear of humans is a source of stress for Holstein dairy cattle and can result when animals are handled aversively. We used aversion learning techniques to determine which handling practices cattle find most aversive. In an aversion race, the cows are repeatedly walked down a race and treatments applied when they reached the end; the time and force required for cows to walk down the race are measured. The animal learns to associate walking down the race with the treatment received; if the treatment is aversive, the animal will take more time and require more force to reach the end of the race than if the treatment is positive. In experiment 1, 54 cows were assigned
Ž .
to four treatments hitrshout, brushing, control, and food . Treatments of 2-min duration were applied three times a day for 4 days. Cows on the hitrshout treatment took more time and required more force to walk through the race than cows on other treatments, while brushed cows took longer to move through the race than cows given food. In experiment 2, 60 cows were
Ž .
assigned to five treatments electric prod, shouting, hitting, tail twist, and control . Treatments of 1-min duration were applied three times a day for 3 days. Cows on the shout and electric prod treatments took more time and required more force to walk down the race than cows on the control treatment. In experiment 3, thirty-six 1–1.5-year-old heifers were assigned to three
Ž .
treatments hand feeding, gentling, or control applied as in experiment 2. Treatments did not affect the time or force required to walk down the race. The aversion race successfully discriminated between handling treatments that differ greatly in aversiveness but lacked sensitivity to distinguish between treatments that were similar. Although many procedural factors must be
)Corresponding author. Present address: Department of Animal Sciences, Purdue University, 1026 Poultry Science Building, West Lafayette, IN 47907-1026, USA.
0168-1591r00r$ - see front matterq2000 Elsevier Science B.V. All rights reserved.
Ž .
considered, aversion learning techniques are an effective method to determine which handling practices cattle find aversive or rewarding.q2000 Elsevier Science B.V. All rights reserved.
Keywords: Dairy cattle; Handling; Aversion; Learning; Mazes; Fear
1. Introduction
Cows find certain forms of handling to be aversive and, consequently, can develop a fear of people which can reduce welfare and milk production and increase the risk of
Ž .
injury to both animals and handlers Hemsworth and Coleman, 1998 . Dairy cows and calves learn to avoid a particular handler as a result of aversive treatment by that handler
Žde Passille et al., 1996; Munksgaard et al., 1997; Rushen et al., 1999 . However, we do
´
.not yet know which handling treatments cattle find aversive. One approach is to use aversive learning techniques, which are based on the principle that animals learn to
Ž .
avoid treatments that they find aversive for a review, see Rushen, 1996 . These
Ž .
techniques have been used with poultry Rutter and Duncan, 1991, 1992 , cattle
ŽSchwartzkopf-Genswein et al., 1997 , sheep Grandin et al., 1986; Rushen 1986 and. Ž .
Ž .
deer Grigor et al., 1998 . One promising procedure involves the repeated application of a treatment at the end of a race and measuring the time and force necessary to return the
Ž .
animal through the race to the place where the treatment was done Karsh, 1962 . The more aversive the treatment, the more the animal will resist returning to that place and the more time and force will be required to move the animal through the race. Aversion raceways based on this principle have been used to assess the aversiveness of simulated
Ž .
shearing to sheep Hargreaves and Hutson, 1990 , the aversiveness of
electroimmobilisa-Ž . Ž .
tion to both sheep Rushen, 1986 and beef cattle Pascoe and McDonell, 1986 and the
Ž .
relative aversiveness of various management practices to red deer Grigor et al., 1998 . This technique has not been used previously to evaluate the aversiveness of various handling procedures for dairy cattle.
This paper describes the results of three experiments aimed at determining the aversiveness of dairy cattle handling practices using the aversion race. In the first experiment, we tested the empirical validity of the aversion race by determining how well it differentiates between treatments known to differ in aversiveness. In the second experiment, we used the aversion race to determine the relative aversiveness of various techniques used to move cows. In the final experiment, we examined if the aversion race can differentiate between treatments thought to be rewarding, rather than aversive, to young heifers.
2. General methods
2.1. Animals and housing
Experiment 1 used lactating multiparous Holstein cows, which were brought in from pasture each morning for milking, then moved from the milking parlour to the test barn. After tests were completed, animals were returned to pasture and milked in the evening. In experiments 2 and 3, non-lactating multiparous Holstein cows and 1–1.5-year-old
Ž .
a room in the same barn as, and adjacent to, the room where experimental procedures were done. Animals were fed at 13:00 h, after experimental procedures were completed.
2.2. Procedures
Experimental procedures were approved by the institutional animal care committee at the Lennoxville Research Centre, itself monitored by the Canadian Council for Animal
Ž .
Care. Animals were placed in a pre-test holding pen 5.3=9.3 m either immediately
Ž .
before experiment 1 or at least 24 h before experimental procedures were initiated
Žexperiments 2 and 3 . All experimental procedures were performed between 08:00 and.
12:00 h.
One animal at a time was moved from the holding pen down an alley to the beginning of the race. The race was 10 m long=1 m wide with 2 m high walls made
Ž .
from solid wood Fig. 1 . Animals could see the person who applied the treatments
Ždressed in red standing sideways not looking at the animal at the end of the race. The. Ž .
race was divided into four equal sections. The animals were placed at the beginning of the first section and allowed 30 s to move through each section. If the animal had not moved through the section once this time had elapsed, the person moving the animals approached the animal from behind and applied increasing levels of force until it entered the next section. The force required to move the animal into the next section was scored
Ž .
using a standardised method derived from Schwartzkopf-Genswein et al. 1997 : 0s
nothing, animal moves through section within 30 s on its own; 1sapproach and speak
Ž .
in a gentle voice; 2spoke side with fingers five times ; 3shit rump with open hand
Žfive times ; 4. shit rump with two open hands five times ; 5Ž . spencil poke on back
Žthree times ; 6. spush and force animal to advance. Near the end of the race, the animals walked up a small ramp into a 2-m long cage where they received assigned treatments.
Ž .
The latency to enter the race after leaving pre-test holding area , the time required to
Ž
move through the race from start of race until the animal entered the individual
.
treatment pen , and the amount of force required to move the animal down the race
Žsummed over the four sections of the race were recorded..
2.3. Statistical analysis
For all three experiments, the total amount of time and the summed force taken to move through the race as well as the latency to enter the race were analysed by analyses
Ž .
of variance using the general linear model procedure of SAS 1990 . The model consisted of two factors: the treatments applied to the animal, which varied between
Ž .
experiments experiment 1, dfs3; experiment 2, dfs4; experiment 3, dfs2 and the
Ž
trial number, which was treated as a repeated measures factor experiment 1, dfs1,10;
.
experiments 2 and 3, dfs3,6 . To correct for initial differences between cows in moving down the race before treatments were applied, we included the measure on the
Ž .
first trial as a covariate dfs1 . We tested for interactions between trial number and the treatment. Contrast statements were used to compare treatments within each experiment
Žeach contrast dfs1 . Due to large variation, data were log transformed before.
analyses, but untransformed values are presented for clarity. In all experiments, prelimi-nary analyses demonstrated no effect of week, group or any interactions between these factors and treatment, and these factors were removed from the final analysis.
3. Experiment 1: Validity of the aversion race
The purpose of this experiment was to test the empirical validity of the aversion race by determining how well it differentiates between treatments known to differ in aversiveness. Previous studies have demonstrated that providing food decreases the distance cows keep from people, while hitting animals increases the distance cows keep from the people, clearly demonstrating that dairy cattle find food to be positive and
Ž .
hitting to be negative Munksgaard et al., 1997; Rushen et al., 1999 . Non-aggressive forms of tactile contact such as brushing or petting are also reported to decrease fear and
Ž .
make animals easier to handle Boissy and Bouissou, 1988; Boivin et al., 1992 .
3.1. Methods
Fifty-four lactating multiparous cows were randomly allocated to one of four treatments.
Ž .
a. Control ns14 . The person stood still, facing the cow with hands in pockets and did not talk or handle the animal.
Ž .
b. Brushing ns14 . The cows were brushed on the neck with a dairy cattle grooming brush while the person spoke softly to them.
Ž .
c. Food ns13 . The cow was simultaneously offered a handful of hay and molasses flavoured feed.
Ž .
d. Hitrshout ns13 . The person hit the animal forcefully four times on the head or neck with an open hand and shouted at the cow for the total duration of the treatment.
Ž
All treatment periods were 2 min in duration. Two groups of four animals one
.
animal per treatment were tested each week. Cows passed through the race three times
Ž
.
treatment . Three different handlers were used. Each cow was always treated by one person only and each person did all four treatments for an equal number of cows. Order of treatments during the day was balanced across groups.
3.2. Results
Overall, the latency for cows to enter the race decreased over the course of the
Ž .
experiment P-0.05, Fig. 2a . There was no significant treatment effect on average
Ž . Ž . Ž .
Fig. 2. Behaviour of cows mean"SE during experiment 1. a Latency to enter the race, b time to move
Ž .
latency and no trial by treatment interaction, although there was a non-significant tendency for cows on the hitrshout treatment to take longer to enter the race than cows
Ž .
on other treatments P-0.10. . On trial 6, cows on the hitrshout treatment took
Ž .
significantly longer to enter the race than control cows P-0.05 and cows on the food
Ž .
treatment P-0.01 . On trial 8, cows on the hitrshout treatment took longer to enter
Ž .
the race than cows on each of the other three treatments P-0.05 .
There was a large decrease from trial 1 to trial 2 in the amount of time to move down
Ž .
the race Fig. 2b for cows on all treatments. Overall, the time to walk through the race
Ž .
differed significantly between treatments P-0.001 . Cows on the hitrshout treatment
Ž .
took longer to walk through the race than cows on the other three treatments P-0.01 . Cows given food took less time to walk through the race than control cows on trial 4
ŽP-0.05 . Brushed cows took longer to walk through the race than cows given food on.
Ž . Ž .
trials 4 and 5 P-0.05 and from control cows on trial 4 P-0.05 .
The amount of force required to move the cow through the race reflected the amount of time required to walk through the race; there was a significant treatment effect
ŽP-0.001 but no trial by treatment interaction Fig. 2c . On average, cows on the. Ž .
hitrshout treatment required more force to move through the race than cows on the
Ž .
other three treatments P-0.01 , while cows given food required less force to move
Ž .
through the maze than cows on the brush treatment P-0.05 . Control cows required
Ž
more force to move through the maze than cows given food on trials 11 and 12 both
.
comparison P-0.05 .
4. Experiment 2: Methods for moving cows
In this experiment we used the race to determine the relative aversiveness of various techniques used to move adult dairy cows.
4.1. Methods
Sixty non-lactating, multiparous cows were randomly allotted to five treatment groups.
a. Tail twist. The tail was grasped near the base and carefully twisted in a clockwise
Ž
manner until slight resistance was felt. The tail was held in this position for 3 s four
.
times per minute .
b. Hit. The cow was hit on the rump with an open hand once every 15 s.
Ž .
c. Electric prod. An electric cattle prod Stockmaster, 30 V made contact with the animal’s rump four times per minute but current was applied only the first time. d. Shout. Experimenter moved to side of animal and shouted loudly at the cow for 5 s, four times during the minute.
The treatments were applied at the end of the race in the treatment pen. All treatment periods were 1 min in duration. In order to facilitate application, treatments were applied from the side of the animal. To ensure that the cows associated the treatment with the person, the person remained in view of the animals while performing the treatment, and returned and stood in front of the animal every time after applying each treatment.
Unlike experiment 1, the cows were familiarised with the race the day before the experiment. During this day, cows were taken to the race and allowed 2 min to walk through each section of the race before force was applied. No treatments were applied when the cow reached the end of the race during this training run.
Two groups of five cows, one per treatment, were tested each week. Cows passed through the race three times a day over 3 days, for a total of nine trials. Treatment order was balanced across groups and one person treated all the animals.
4.2. Results
Over the course of the experiment the average latency to enter the race did not show
Ž .
any consistent change over trials Fig. 3a and there was no treatment effect or trial by
Ž .
treatment interaction. There was a trial by treatment interaction P-0.05 for the
Ž .
average time to walk through the race Fig. 3 . Cows on the electric prod treatment took more time to walk through the race than cows on the control treatment on trials 5, 7, 8
ŽP-0.05 , and 9. ŽP-0.01 . Cows on the shout treatment took more time to walk.
Ž .
through the race than control cows on trial 5 P-0.05 . Cows on the control, hit, and tail twist treatment did not differ from each other in the amount of time to walk through the race.
The amount of force required to move the cows through the race also showed a trial
Ž .
by treatment interaction Fig. 3c . Cows on the electric prod treatment required more
Ž
force to move down the race than control cows after trial 3 trial 4, P-0.05; trial 5,
.
P-0.01; trial 6, P-0.05; trials 7 and 8, P-0.01; and trial 9, P-0.001 , while cows
Ž
on the shout treatment also differed from control cows after trial 3 trial 4, P-0.05;
.
trial 5, P-0.01, trials 6–9, P-0.05 . Cows on the tail-twist and hit treatments did not differ with control or each other.
5. Experiment 3: Rewarding treatments for heifers
The purpose of this experiment was to determine if the aversion race could be used to differentiate between treatments thought to be rewarding rather than aversive to heifers.
5.1. Methods
Thirty-nine heifers, aged 1–1.5 years old, were randomly allotted to three treatments.
a. Control. The experimenter turned and faced the animals then remained still with hands in pocket.
Ž . Ž . Ž .
Fig. 3. Behaviour of cows mean"SE during experiment 2. a Latency to enter the race, b time to move
Ž .
through the race, and c force required to move through the race.
c. Hand feeding. The experimenter, in a crouched position, offered hay from one hand and a molasses-flavoured feed from the other. One person treated all the animals.
All treatment periods were 1 min in duration. As in experiment 2, animals were walked through the race, once, the day before the experiment. In the first week of the
Ž .
experiment, we used one group of three heifers one per treatment . After the first week
Ž .
5.2. Results
Over the course of the experiment the average latency to enter the race decreased
ŽP-0.01, Fig. 4 . The average amount of time, and force required to pass through the.
Ž .
race also decreased over successive trials P-0.05 . However, there was no treatment effect or trial by treatment interaction. Contrast comparisons found no differences between any treatments in the overall mean latency to enter the race, the time to walk
Ž . Ž . Ž .
Fig. 4. Behaviour of calves mean"SE during experiment 2. a Latency to enter the race, b time to move
Ž .
through the race, or the mean force required to move the animal through the race. Nor did these variables differ at any one specific trial. Of the 13 heifers on the food trial,
Ž .
only 8 started to eat consistently defined as eating on two consecutive trials by the fourth trial. Since this may have effected the results, the data were re-analysed using only these 8 animals. However, the results of the analysis were the same as when the entire data set was used.
6. Discussion
The results demonstrate the effectiveness and limitations of the aversion race to evaluate handling practices for dairy cattle. Experiment 1 demonstrated the empirical validity of the aversion race by comparing treatments known to differ in aversiveness. Adult cows clearly demonstrated which treatments were aversive and which were rewarding; cows that were hit and shouted at took longer to enter the race took more time and required more force to move down the race than cows that were given food. These results are in agreement with other studies showing that cows avoid handlers that
Ž .
hit them Breuer et al., 1997; Munksgaard et al., 1997; Rushen et al., 1999 and
Ž .
approach handlers that feed them Jago et al., 1999, Rushen et al., 1999 . The use of the aversion race to clearly differentiate between a known positive and a known negative handling treatment allows us to conclude that it is a valid method of evaluating the aversiveness of various handling practices.
Experiment 1 also examined human–animal contact that did not involve feeding
Žbrushing and petting . Non-aggressive forms of tactile contact between humans and.
Ž .
animals gentling, petting, brushing have often been reported to decrease fear of
Ž
humans and make handling easier in cattle Boissy and Bouissou, 1988; Boivin et al.,
.
1992; de Passille et al., 1996; Munksgaard et al., 1997 . However, these studies combine
´
contact with providing food. The few studies that have looked only at gentle contact
Ž .
report conflicting results Boissy and Bouissou, 1988; Hemsworth et al., 1996 . Our results suggest that for dairy cows, brushing was more aversive than being given food or receiving no treatment at all, at least during initial treatments. These results support the
Ž .
conclusion of Jago et al. 1999 who found that gentling was less effective than giving food in the development of human–animal interactions. However, the differences between cows on the brushing and feeding treatments decreased with time suggesting
Ž .
that cows may habituate to the brushing. Similarly, Boivin et al. 1998 reported that acceptance of contact appears to be more the result of a habituation process than one of positive reinforcement.
In the second experiment, we compared techniques commonly used to move cattle. Cows treated with an electric prod took more time and required more force to walk down the race than control cows, and this was the most aversive treatment on the final trials. Both cattle and swine have been found to avoid their handlers that use electric
Ž .
prods Gonyou et al., 1986; de Passille et al., 1996 . Cows that were shouted at in our
´
Ž . Ž
Waynert et al. 1999 who found that beef cattle responded more higher heart rates and
.
more movements when played the sounds of a shouting human voice than metal
Ž .
clanging. In contrast, Hemsworth et al. 1986 found no differences in the approach behaviours of young pigs to humans using a loud voice or a soft quiet voice.
The race did not find that the other handling treatments, tail twist and hitting, to be significantly more aversive than the control. Twisting the tail of the cow results in the
Ž .
animal moving forward and is thought to be aversive Grandin, 1994 . Although our results suggest that tail twisting is only slightly aversive, it must be done with great care as tail breakage may result. Hitting the cow on the rump with an open hand was not found to be significantly more aversive than control. Hitting has been shown to increase
Ž
flight distance in both cows Breuer et al., 1997; Munksgaard et al., 1997; Rushen et al.,
. Ž .
1999 and pigs Gonyou et al., 1986; Hemsworth and Barnett 1991 and cows being hit
Ž .
are reported to defecate and urinate more Munksgaard et al., 1997 . However, hitting
Ž .
the rump of the animal as done in experiment 2 may be relatively less aversive to the cow then hitting the muzzle of the animal. Finally, the inability of the aversion race to discriminate significantly between hitting and control indicates the limits on the sensitiv-ity of the test. There are numerous procedural and animal factors that may explain the failure to clearly distinguish between some handling treatments. The inability to detect differences between handling treatments in experiment 2 is largely due to the large variation among individual cows. This was substantially less in experiment 1 than in experiment 2, which may be due to differing experience that the animals had with human contact. The non-lactating cows on experiment 2 had little daily contact with people, while the lactating cows on the first experiment were handled at least twice a day.
Heifers are generally more difficult to handle then adult cows; the refusal of dairy heifers to enter the milking parlour is a well-known problem in the dairy industry
ŽAlbright and Arave, 1997; Bremner, 1997 . Hutson 1985 suggested that providing a. Ž .
positive reward immediately after handling may make animals easier to move in the future. Since providing animals with food was found to be a positive treatment in
Ž
experiment 1 and gentling is thought to be positive for calves Boissy and Bouissou,
.
1988 , we hypothesised that heifers would move through a race more easily if these treatments were provided at the end of the race. This was not the case, as heifers that received these treatments did not differ in the amount of time or force required to walk down the race in comparison with heifers that did not receive any treatment. Heifers that had little experience with people were offered food from a person’s hand. Consequently, they may have found both gentling and taking food from the hand of a relatively unfamiliar person aversive.
Ž . Ž .
with pigs Talling et al., 1996 and beef cattle Waynert et al. 1999 . Repeated exposure is also important to minimise other sources of fear associated with using the race. The novelty of the procedure and the handling involved with moving the animal to and from
Ž
the race are potential sources of fear Boissy, 1995; Schwartzkopf-Genswein et al.,
. Ž .
1997 which repeated exposure should minimise Grandin, 1980 . In all of our experi-ments, the amount of time taken by animals on the control treatment decreased over the course of the experiment.
Of the measures taken, we conclude that the latency taken to move the animal into the race is least useful. Although our measure of latency to enter the race differed
Ž
between treatments on experiment 1, it was generally a less sensitive measure more
.
variable than the amount of time and force required to move through the race. This may have been because it was the most difficult measure to standardise. Although animals were moved to the race entrance in a standardised manner, occasionally animals would balk at the entrance to the race, turn and run back toward the pre-test holding pen. As a result the overall latency to enter the pen could be a reflection of the skills of the handler, the distance the animal ran back towards the holding pen, the size of the animal or other factors not associated with the treatment. The force to move through the race is difficult to standardise, and this also affects the total time taken to move through the race. Although the handler always used the same pattern of force application, the intensity could have varied. Furthermore, if the animal required a great deal of force to move through the race then animals latency to enter and time to move through the race may be associated with the application of force rather than the treatment received at the end. Automating the moving of the animal down the race, in a manner where constant pressure is applied to the cow and resistance to this pressure is quantified would improve the quality of the measures taken in the race.
7. Conclusion
Measuring the extent to which animals avoid aversive situations and using these
Ž
measure to rank different procedures is a well-established methodology Russell and
.
Burch, 1959 . The aversion race successfully discriminated between handling treatments that differ greatly in aversiveness but lacked a sensitivity to distinguish between treatments that were similar. This lack of sensitivity may be explained by numerous procedural and animal factors that require further investigation. Despite the issues raised, the aversion raceway is a method that can be performed fairly quickly with a minimal amount of training, unlike other procedures such as operant conditioning. Thus aversion learning techniques continue to be a promising approach to evaluate various handling practices.
Acknowledgements
for their technical assistance in running the experiments. We also thank the staff of the dairy barn for their co-operation. This research was supported by a grant from Novalait.
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