The response of beef cattle to noise during handling

Applied Animal Behaviour Science 62 Ž1999. 27–42

The response of beef cattle to noise during handling D.F. Waynert, J.M. Stookey ) , K.S. Schwartzkopf-Genswein, J.M. Watts, C.S. Waltz Department of Herd Medicine and Theriogenology, Western College of Veterinary Medicine, 52 Campus DriÕe, UniÕersity of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4 Accepted 27 August 1998

Abstract Noise is often overlooked as a potential source of fear for cattle during handling. Fifty-nine yearling beef heifers Ž362 " 26 kg. were used in a study to evaluate their behavioural and physiological response to noises during a 1-min exposure. In Trial 1, 29 heifers that were naive to the treatments were assigned to either prerecorded handling noise ŽNoise, n s 14. composed of humans shouting and metal clanging or no prerecorded noise ŽSilence, n s 15. and tested daily for 5 consecutive days. In Trial 2, the remaining 30 naive heifers were assigned to one of the two components of the Noise treatment, either the prerecorded voices of people shouting ŽVoice, n s 15. or recorded noise of metal-on-metal clanging ŽClanging, n s 15. and again tested for 5 consecutive days. Heifers were tested individually while they were constrained on an electronic scale within a chute complex. Remote telemetry was used to record heart rate ŽHR.. The behavioural response was quantified by an electronic movement-measuring device ŽMMD.. The MMD monitors changes in voltage from the load cells of the electronic scale and records a peak when a trend in voltage is reversed. Heifers exposed to Noise had higher HR Ž P - 0.01. and recorded more movement peaks Ž P - 0.05. during the testing period than heifers exposed to Silence. When the Noise treatment was separated into the two components and played back in Trial 2, the sounds of humans shouting ŽVoice. appeared to be more alarming, based on HR and movement, than the sounds of metal striking metal ŽClanging.. Both the HR and the number of MMD peaks were greater for the Voice heifers Ž P - 0.05 and P - 0.01.. Sounds were played back at equal volumes, therefore some intrinsic differences in the origin or significance of the sounds to the heifers must account for the differences in response. Heifers did show signs of habituation to the noises over the 5-day trials, but it is unknown if cattle would habituate to similar noises encountered during infrequent handling, as is typical with normal management procedures.

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Corresponding author. Tel.: q1-306-966-7154; fax: q1-306-966-7159.

0168-1591r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 1 5 9 1 Ž 9 8 . 0 0 2 1 1 - 1

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By eliminating or reducing the sounds of metal clanging and particularly the sounds of humans shouting should help reduce the level of fear cattle experience during handling. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Beef; Cattle; Noise; Fear; Handling

1. Introduction Fear causes both behavioural and physiological changes in cattle. A stimulus that is of high intensity, is novel, or presented suddenly, may be considered frightening ŽWood-Gush, 1983.. Certain types of noise during the routine handling of cattle may fit this description. Cattle producers are undoubtedly aware of the noise associated with handling or processing cattle. It is likely that many handlers accept the noise as part of the job, though they may admit the noises of people shouting and of the chute and gates clanging and banging are a source of irritation for themselves. Indeed, noise has been demonstrated as a source of fatigue and irritability for people in the workplace ŽMelamed and Bruhis, 1996; van Raaij and Oortgiesen, 1996.. Noise as a cause of fear in cattle is often overlooked, though some noise may be more irritating to cattle than people, since cattle can hear sounds of much higher frequencies than humans ŽKilgour and Dalton, 1984.. Cattle may associate some sounds with previous negative experiences. In addition, the noises during handling may be novel to the cattle and as a result the sounds may be more frightening. It has been shown that noise contributes to transport stress in calves ŽFrancesco et al., 1990.. Observations at slaughter plants indicate that animals held overnight in noisy yards were more agitated, and following slaughter were found to have more bruising, than animals kept in a quieter environment ŽEldridge, 1988.. Noise, such as the sound of a truck horn, was shown to increase the heart rates ŽHR. of free-ranging cattle ŽArave et al., 1991., while cattle habituated to the sounds and sights of cars and trucks will readily graze along highways and seldom react ŽGrandin, 1997.. This seems to indicate that it is the suddenness, novelty and the unexpected nature of sounds that elicit the fear response. Heart rate is frequently seen to rise in association with sudden unpleasant experiences, for example, branding ŽLay et al., 1992., electric shock ŽLefcourt et al., 1986., a sudden and unexpected stimulation ŽBroom and Johnson, 1993., isolation ŽHopster and Blokhuis, 1994., or exposure to a novel environment ŽVeissier and le Neindre, 1992.. These situations, whether physical or psychological assaults, are often considered stressful. Each of these conditions have received some investigation due to the negative impact they may have on livestock. To date, no scientific studies have been reported which consider what effect noise during handling may have on cattle, although it has been suggested that noise does generally contribute to difficulty in moving cattle at slaughter plants ŽGrandin, 1996.. Our objectives were to investigate the response of cattle to typical handling noises and to determine whether cattle show varying fear responses to human Žshouting. and nonhuman Žmetal-on-metal clanging. handling noise.

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2. Animals, materials, and methods Fifty-nine yearling crossbred beef heifers, with an average weight of 362 " 26 kg were divided into groups for use in two trials. In Trial 1, 29 naive heifers were randomly assigned to either prerecorded handling noise ŽNoise. Ž n s 14. or no prerecorded noise ŽSilence. Ž n s 15. and tested on 5 consecutive days. In Trial 2, the remaining 30 naive heifers were randomly assigned to either the prerecorded voices of people shouting ŽVoice. Ž n s 15. or recorded noise of metal-on-metal clanging within the chute ŽClanging. Ž n s 15. and again tested daily for 5 consecutive days. In both trials, heart rate was measured as an indicator of the physiological response to noise, and movement was measured while the animal was exposed to the treatment as an objective measure of an overt behavioural response. 2.1. Noise stimuli The noise stimuli used during the trials were prerecorded. Sounds typically heard during cattle handling were recorded using a Sony TCM5000 cassette recorder and attached microphone. One of the recordings contained the sounds of two men shouting to encourage cattle movement. The other recording consisted of sounds originating from a cattle chute: metal gates closing, metal-on-metal clanging and the simulated sounds of cattle moving within the chute. These two recordings were digitally sampled at 44.1 kHz and then edited to a uniform length of 1 min each. The two 1-min recordings were then equalized for peak volume levels, combined, and dubbed onto a single audio tape for use in Trial 1. The recordings were used separately in Trial 2. The average noise level of the voice recording as measured during playback was 86 dBŽc. with a peak value at 95 dBŽc. and an accuracy of "1 dB ŽGeneral Radio Sound-Level Meter type 1565-B: Concord, MS, USA.. The average noise level of the clanging sounds were 85 dBŽc. with a peak level of 94 dBŽc.. The dBŽc. unit of measurement refers to a sound level value as measured using a weighting network with essentially flat frequency response characteristics between 140 Hz and 4 kHz. Padding was added to the chute complex in areas where metal could strike metal as a method of reducing extraneous noises that were not treatment related. 2.2. Heart rate measurement Remote telemetry ŽParagon 420 Cardiac Monitoring System and TM8 Patient Transmitters: Quinton Instrument, Seattle, WA, USA. was used to record heart rate during both trials. Heart rates were calculated using the ECG printout which moved at a known speed Ž s . of 1500 mmrmin. The distance in mm Ž d . spanned by several Žusually 10. interbeat intervals Ž n. was measured from the peak of the oth to the peak of the nth QRS complex. Heart rate was calculated by the formula: HR s nrd = s. Several days before the trials, heifers were restrained in a squeeze chute Žseparate facilities from the test area. to apply two surgical skin staples Ž5.7 mm = 3.8 mm

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APPOSE) ULC Disposable Skin Staples, American Cyanamnid, Wayne, NJ, USA.. The electrode leads from the transmitters were fitted with alligator clamps to allow attachment to the skin staples. The staples were applied to a small shaved area approximately 25 cm2 . The staple on the left side was positioned approximately 7 cm caudal and 5 cm dorsal to the elbow, and the other staple approximately 5 cm caudal and 10 cm ventral to the dorsal tip of the right shoulder blade. An 8 cm strip of Velcro was glued along the heifer’s back between the shoulder blades ŽKamar Adhesive, Kamar, Steamboat Springs, CO, USA.. The Velcro strip served as an anchor for the heart rate transmitter, which was also fitted with Velcro for easy attachment and removal. The Velcro strip and staples remained on the heifers for the duration of the 5-day trials and were removed after measurements on the last day of each trial. Both the staples and the Velcro strip caused little or no response by the animals at the time of application or removal, leading us to believe the procedures were relatively painless and insignificant to the heifers. 2.3. Measurement of moÕement Movement was measured using an electronic movement-measuring device ŽMMD. ŽStookey et al., 1994.. The MMD has an independent power source and is connected to the load cells attached to a single animal electronic weigh scale. Analogue changes in voltage that occur as the animal moves on the scale are digitally sampled at a rate of 122 timesrs for a period of 1 min. The MMD records a peak when a trend of increasing or decreasing voltage Ždefined by a minimum of ten consecutive digital samples showing changes in the same direction. is reversed. It then reports the number of peaks on an LCD display. Simply stated, the number of peaks was indicative of the amount of movement made by the heifer during the 1-min test. The number of peaks increased the more the animal moved or conversely, the lower the number of peaks, the ‘stiller’ the animal stood during the test. The number of peaks has been found to be highly correlated to the amount of movement which can be detected by video analysis ŽStookey et al., 1994.. Earlier studies ŽStookey et al., 1994. demonstrated that cattle show elevated MMD scores when visually isolated from conspecifics. To minimize isolation stress in these trials the subject was always tested while a familiar companion animal Žnot used in the experiment. was standing directly ahead, within visual contact of the subject. On day 5 of Trial 2, movement data were not available due to electrical problems with the MMD. 2.4. Testing procedure Heifers were moved daily from their home pen to a sorting area where treatment groups were separated. The second group to be tested was moved to a pen approximately 20 m from the testing barn to ensure heifers did not hear the other treatment while they waited to be tested. The order in which the treatment groups were tested was alternated each day. The group to be tested was moved in single file through a curved

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chute which led into the testing barn. Prior to entering the barn, electrode leads were attached to the skin staples and the transmitter was fastened to the Velcro on the heifer’s back. Several transmitters were used in rotation so that while one animal was being tested the next animal was fitted with the transmitter. This allowed a minimum of 5 min to elapse after transmitter attachment without further human contact. Each animal entered the testing barn individually and was confined on the electronic scale directly behind the companion animal. No people were in view of the subject animal during the entire testing period. Measurements were taken during three distinct time periods: Ž1. pretreatment, Ž2. treatment exposure and Ž3. posttreatment. The pretreatment period consisted of a 1-min period in which heart rate and movement measurements were taken to serve as reference or baseline measurements. No treatments were applied during the collecting of baseline measurements. Following this first minute, there was a pause of about 30 s during which the MMD made its calculations. The 1-min treatment period followed, during which the heifers were exposed to their respective treatments. A Sanyo cassette player with two detachable speakers Žplaced approximately 1 m above and centrally located 0.5 m on both sides of the scale. was used to play back the appropriate stimulus for the 1-min test. Following the 1-min stimulus, another pause of 30 s was needed for MMD calculation. Lastly, the 1-min posttreatment period was maintained for each heifer during which time heart rate and movement measurements were taken again in the absence of treatment stimuli. The posttreatment period was added to determine whether heart rate and movement measurements would return to baseline levels following the treatments. At the end of the posttreatment period the test animal was allowed to return to its home pen. 2.5. Statistical analyses Data from Trials 1 and 2 were analyzed separately. However, in both trials heart rate and movement data were analyzed using a repeated measures ANOVA from the general linear models procedure in SAS Institute Ž1990.. Treatment served as the independent variable in the univariate analyses and heart rate Žbpm. and movement measurements ŽMMD peaks. as the dependent variables. The repeated measures analysis for HR in Trial 1 included 21 observations and omitted eight animals from the analysis because of missing HR values within the 5 days; 28 observations were used in the analysis for MMD peaks. The repeated measures analysis for Trial 2 used 28 and 29 animals in the analysis for HR and MMD peak data, respectively. A two sample t-test ŽStatistix w for Windows, 1996. was conducted to detect treatment effects within each day, after an overall treatment and time effect was found to be significant using the repeated measures ANOVA. Three separate paired t-tests ŽStatistix w for Windows, 1996. were used to detect differences within treatments for each day for the measurements collected during the three time periods Žpretreatment vs. during treatment; during treatment vs. posttreatment; pretreatment vs. posttreatment.. The changes in heart rates and movements, as defined by measurements collected during treatment exposure minus pretreatment values, were also tested using a repeated measures ANOVA for both trials.

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3. Results 3.1. Trial 1: effects of noise Heifers exposed to the Noise treatment had an overall higher heart rate during the 1-min test period compared to heifers in the Silence group Ž P - 0.01. ŽTable 1.. However, on days 1 and 3, the Noise group already had higher heart rates before the treatment began and there was an overall treatment effect detected before the exposure to the noise Ž P - 0.05.. Even so, the HR of the heifers exposed to the Noise treatment was numerically Žthough not statistically. higher during exposure to noise, while the Silence group’s heart rate either decreased, as on day 1, or remained the same during the exposure to the treatment. The recordings of the noise appeared to increase the HR in the Noise group on the first 4 days of the experiment. In contrast, as the experiment advanced the Silence treatment group had elevated heart rates prior to leaving the testing area in comparison to their HR upon entering. The difference in the change in HR between the pretest period and the test was greatest between the treatment groups on day 1 Ž P - 0.01. ŽFig. 1.. While the HR during the pretest and test periods was not significantly different for the Noise group on day 1 Žas shown in Table 1., the direction and magnitude of change in HR between the pretest and test periods was statistically different between the two treatments as shown in Fig. 1. The HR of the Noise group increased during the test on day 1, while the HR for the Silence group decreased. The Noise group continued to exhibit an elevated HR during exposure to the sound recording for the first 4 days of the experiment. The HR for the Silence group was basically unchanged between the pretest and test periods after day 1. Like the HR measurements, the amount of movement was measured during three distinct time periods each day. Heifers exposed to noise, overall, had a higher number of MMD peaks Žmore movement. before and during the test compared to the Silence group Ž P - 0.05. ŽTable 1.. On days 1, 2 and 5 of the test, the Noise group had higher MMD values during the test period compared to the pretest period, but this was also true for the Silence group on days 3 and 4. The amount of movement decreased numerically after the Noise test period was complete on all days except day 3, but the decrease was only significant on day 1. This pattern was not observed for the Silence group. Instead, the Silence group had more movement after the test period than during the pretest period on 3 out of 5 days, while this was only true for the Noise group on day 5 ŽTable 1.. The Noise group consistently displayed more movement during the test period compared to the pretest measurement. The Noise group also had greater changes in movement between the pretreatment and the treatment periods ŽFig. 2.. 3.2. Trial 2: metal clanging Õs. shouting Overall, the Voice treatment had higher HR Ž P - 0.05. and more MMD peaks Ž P - 0.01. during the test period compared to heifers exposed to the Clanging treatment ŽTable 2.. However, on 3 out of 5 days of the trial, the HR was already different between the two groups during the pretest period. There were also preexiting MMD

Day of trial a

Treatment

Heart rate 1 min before treatment appliedb

Heart rate during treatment c

Heart rate 1 min after treatment

No. of peaks 1 min before treatment appliedd

No. of peaks during treatment e

No. of peaks 1 min after treatment

Day 1

Noise Silence Noise Silence Noise Silence Noise Silence Noise Silence

100.9"3.15 x,y 89.8"2.32 x 93.6"3.16 92.5"1.96 99.1"3.49 87.0"1.62 y 93.8"3.71 93.0"3.62 86.2"2.47 80.4"1.44 y

106.1"3.27 x 79.7"1.50 y 97.1"2.44 91.3"1.99 104.0"4.24 87.7"2.07 x,y 102.3"3.95 93.7"2.90 85.7"2.31 82.8"1.24 x,y

97.7"3.72 y 80.2"1.55 y 92.3"2.79 95.8"2.03 104.5"4.13 91.9"1.99 x 96.3"3.36 93.8"3.08 89.5"2.27 83.8"1.43 x

33.8"10.7 y 11.6"5.73 43.5"8.95 y 20.8"9.41 y 68.7"13.3 34.4"12.7 y 63.4"17.1 14.3"11.4 y 31.1"14.3 y 35.4"12.1

71.8"11.7 x 13.4"4.71 74.3"11.8 x 24.0"9.45 x,y 84.5"11.6 64.6"12.8 x 94.7"14.1 42.0"10.8 x 79.5"16.1x 44.4"8.53

37.1"10.9 y 18.1"6.25 52.5"10.2 x,y 46.1"11.3 x 89.4"12.7 67.1"12.5 x 86.1"14.1 31.7"7.17 x 77.4"18.2 x 56.9"13.0

Day 2 Day 3 Day 4 Day 5 a

Day of trial had significant effect on HR and tended to influence the number of peaks Ž P - 0.0001 and P s 0.059, respectively.. HR measured before test differed overall between treatments Ž P - 0.05.. c HR measured during test differed overall between treatments Ž P - 0.01.. d No. of peaks recorded by the MMD before the 1-min test differed overall between treatments Ž P - 0.05.. e No. of peaks recorded by the MMD during the 1-min test differed overall between treatments Ž P - 0.05.. x,y Within each type of measurement ŽHR or no. of MMD peaks. values within a row with different superscripts differ Ž P - 0.05.. Bolded values within columns differ between treatments within that day Ž P - 0.05.. b

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Table 1 The average heart rate response Ž"SE. and the amount of movement quantified in beef heifers before, during, and after a 1-min exposure to silence or noise treatments

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Fig. 1. Differences in heart rates between test and pretest periods for heifers exposed for 1 min to prerecordings of Noise or Silence each day for 5 consecutive days. Ž)) P - 0.01..

differences between the two groups on 2 of the 4 days where data were available. It is likely that heifers waiting outside prior to being tested could hear the recordings being played back and may have been influenced by the treatment before entering the testing area.

Fig. 2. Differences in movement between test and pretest periods for heifers exposed for 1 min to prerecordings of Noise or Silence each day for 5 consecutive days Ž) P - 0.05; )) P - 0.01.. Movement is represented in MMD peaks. The MMD Žmovement-measuring device. monitors changes in voltage from the load cells of the electronic scale and records a peak when a trend in voltage is reversed.

Day of trial a

Treatment

Heart rate 1 min before treatment appliedb

Heart rate during treatment c

Heart rate 1 min after treatment

No. of peaks 1 min before treatment applied

No. of peaks during treatment d

No. of peaks 1 min after treatment

Day 1

Voice Clanging Voice Clanging Voice Clanging Voice Clanging Voice Clanging

107.3"3.44 x 88.3"2.66 x 94.7"3.02 86.7"3.28 88.6"3.24 80.0"2.65 86.7"2.38 74.9"2.29 y 81.7"3.85 69.8"3.30

100.5"3.44 x,y 82.2"2.02 y 92.2"3.33 86.7"2.96 90.0"3.50 76.9"2.17 84.0"2.29 76.0"2.55 x,y 86.2"3.69 74.4"3.72

94.3"3.25 y 79.6"2.46 y 88.9"3.80 84.0"3.56 89.2"3.24 74.7"2.71 85.7"2.56 79.8"2.33 x 81.2"3.10 69.7"2.69

29.3"9.17 y 13.5"5.86 57.6"10.8 21.7"4.45 y 39.8"12.0 9.5"6.62 y 15.8"7.07 y 9.1"4.55 y nra nra

60.5"11.1x 12.8"6.42 70.2"10.1 31.0"4.63 x 46.5"10.8 22.3"5.99 x 37.3"5.33 x 11.8"6.30 x,y nra nra

32.7"9.82 y 18.0"5.95 52.2"9.75 29.5"5.26 x,y 42.3"12.2 30.9"6.73 x 41.3"6.45 x 22.3"7.00 x nra nra

Day 2 Day 3 Day 4 Day 5 a

Day of trial had significant effect on HR and the number of peaks Ž P - 0.001.. HR measured before test differed overall between treatments Ž P - 0.05.. c HR measured during test differed overall between treatments Ž P - 0.05.. d No. of peaks recorded by the MMD during the 1-min test differed overall between treatments Ž P - 0.01.. x,y Within each type of measurement ŽHR or no. of MMD peaks. values within a row with different superscripts differ Ž P - 0.05.. Bolded values within columns differ between treatments within the day Ž P - 0.05.. b

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Table 2 The average heart rate response Ž"SE. and the amount of movement quantified in beef heifers before, during and after a 1-min exposure to recorded voices of humans shouting or clanging metal sounds

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Fig. 3. Differences in heart rates between test and pretest periods for heifers exposed for 1 min to prerecordings of humans shouting ŽVoice. or the sounds of metal striking metal ŽClanging. each day for 5 consecutive days.

Unlike Trial 1, the Voice and Clanging treatments used in Trial 2 did not result in any significant differences in the changes in HR between the test and the pretreatment period ŽFig. 3.. In other words, whatever changes in HR occurred between the pretest and treatment period for one treatment group occurred in a similar fashion for the other

Fig. 4. Differences in movement between test and pretest periods for heifers exposed for 1 min to prerecordings of humans shouting ŽVoice. or the sounds of metal striking metal ŽClanging. each day for 5 consecutive days Ž) P - 0.05.. Movement is represented in MMD peaks. The MMD Žmovement-measuring device. monitors changes in voltage from the load cells of the electronic scale and records a peak when a trend in voltage is reversed.

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treatment group. In contrast to the HR data, there were treatment differences in the amount of movement displayed between the test and pretest periods. The Voice group had greater MMD differences on days 1 and 4 than heifers exposed to Clanging ŽFig. 4.. 4. Discussion There are several factors which may contribute to an individual’s response to a fear-evoking stimulus. Breed Žle Neindre, 1989. and temperament ŽBoissy and Bouissou, 1995. play a role in determining the level of fearful behaviour an animal will show in a given situation. Heifers that were averse to a particular stimulus tend also to be more reactive in general ŽBoissy and Bouissou, 1995.. Previous handling also plays an important part in determining their response. Boivin et al. Ž1994. reported that positive early handling made calves easier to work with and more accepting of restraint. Calves treated unpleasantly were more likely to develop fear towards humans Žde Passille´ et al., 1996. and were, therefore, likely to be more difficult to handle. Cows which were restrained in a chute by electroimmobilization showed more aversion and had elevated heart rates when approaching the same chute even 6 months later ŽPascoe, 1986.. To date, there have been no specific studies reported on the influence and adverse nature of noise during handling in cattle. 4.1. Response to noise Heifers exposed to the playback recordings of the combined sounds of humans shouting and metal clanging ŽNoise. had higher heart rates and moved more during the testing period than their counterparts who were exposed to no recorded sounds ŽSilence. ŽTable 1.. We believe the elevated heart rates and the increased movement are indicative of an increased level of fear experienced by the Noise heifers. Increased HR and escape movements are the normal components of the fear response in cattle and most other ruminants, though Kilgour Ž1975. reported that one cow among 50 became immobile in response to a fearful situation during an open field test. In our two trials, the HR and the number of peaks were significantly correlated Ž rs s 0.48 and rs s 0.47, Spearman’s rank order correlations, Trials 1 and 2, respectively., suggesting that both measures may be indicative of the level of fear. Alternatively, more movement may cause HR to rise due to a physiological response and not in response to fear. However, if HR increased simply due to a physiological response brought about through increased movement, then some aspect of the Noise treatment must have initially caused the Noise group to move more than the Silence group. We believe fear was a likely cause of the increased movement and therefore fear, either directly or indirectly, led to an increase in HR. The baseline HR prior to treatment exposure was already higher in the Noise group than in heifers assigned to the Silence treatment on days 1 and 3. Also the baseline movement levels recorded prior to treatment were already higher in the Noise group than in the Silence group on days 1 and 4. A preexisting difference among the groups would theoretically bias the results and negate treatment effects. However, the preexisting difference was likely treatment-related, since the heifers waiting immediately outside the facility were probably able to hear their respective treatment sounds coming from the

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testing area. The decision to separate the treatment groups during testing insured that heifers from one group were not exposed to the other treatment prior to entering the test. Unfortunately, there was no reasonable means of preventing heifers from hearing their own treatment while they waited outside prior to testing. While the arrangement may not have been ideal, the baseline levels measured prior to testing Žassuming HR and movement were responses to preexposure. are in agreement with the measurements during treatment exposure. Both pretreatment and treatment measurements indicate that the Noise treatment was more alarming than the Silence treatment. In addition, the change in levels from the pretreatment period compared to the treatment period was also greater for the Noise than the Silence group ŽFigs. 1 and 2., again suggesting the Noise treatment was more alarming. It is possible that the heifers were also responding to alarm substances from urine or faeces which were left in the testing area by previously tested heifers. There is some evidence that alarm substances do exist in urine of cattle ŽBoissy and Terlouw, 1997.. Though it could be argued that grouping heifers by treatment and testing one entire treatment group prior to the other would have contributed to an alarm substance response, conversely a random testing order may have negated any real treatment effects, due to sound, if animals were simply responding to pheromones left by the previous animal. In the present design, any effect of alarm odors upon the response would itself have been a consequence of the treatment. The general pattern of changes in measured values ŽHR and movement. between the two treatment groups was quite different during Trial 1 ŽTable 1.. While the Noise group generally had increased HR and movement during the test period and decreased levels after treatment, the Silence group generally had increased HR and movement as the time advanced through the pretreatment, treatment and posttreatment periods. It is possible that during the posttreatment period, the Noise treatment heifers relaxed. The Silence group may have become progressively more agitated as time elapsed and as they remained constrained on the scale. As heifers became familiar with the treatment protocol over subsequent days, heifers from both treatment groups may have been anticipating release from the scale near the end of the testing period. The Noise group may have had cues Ži.e., the end of the noise treatment. which allowed them to better judge the duration of time until they would be released, whereas the Silence group had fewer cues. There were no interruptions between the three time periods Žpretreatment, treatment, and posttreatment. for the Silence group. For this reason, the Silence heifers may have begun anticipating release prematurely. This anticipation may have caused the increase in heart rate and movement that was observed during the treatment and posttreatment periods even though the treatment period for the Silence group was no different than their pretreatment period. Anticipation can contribute to anxiety in animals by causing them to be constantly prepared to react to a situation ŽBroom and Johnson, 1993.. 4.2. Response to metal clanging Õs. shouting When the Noise treatment was separated into the two components and played back in Trial 2, the sounds of humans shouting ŽVoice. appeared to be more alarming than the sounds of metal striking metal ŽClanging. based on the HR and movement measure-

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ments Žsee Table 2.. Both the HR and the number of MMD peaks were greater for the Voice heifers Ž P - 0.05 and P - 0.01, respectively.. As in Trial 1, there were preexisting differences between the two treatment groups as detected in their baseline values. Again, these pretreatment differences were likely caused by the heifers being able to hear their respective treatment sounds while they waited outside the facility. While the pretreatment difference would normally be problematic and suggest a biased allotment, observing this difference in two independent trials strengthens the argument that the treatments themselves were contributing to the pretreatment differences. Since the two sounds were equalized for volume levels, the treatment differences must have been caused by inherent differences in the significance of the sounds to the heifers. The pretreatment differences that were evident in both trials also indicate that sound is not easily limited to a specific region within a handling facility. Noise has the potential to reach beyond the point of origin Žor in this experiment the treatment area. and influence the physiology and behaviour of cattle waiting to enter the work area. One major difference between the two sounds was the nature of the origin. The Voice recording was from a biological source, whereas the Clanging recording was a mechanical sound. It is possible that biological sounds originating from another species would be innately more significant to a prey species, like cattle, than a mechanical sound. This would be particularly true if the heifers were not familiar with the sounds of human voices. In addition, the voice recordings consisted of vocal inflections and tones specifically intended to facilitate movement of cattle. It is uncertain if recordings of human voices in general are capable of causing the same response in cattle as we observed. Another possibility is that Voice was more novel than the Clanging treatment. Mechanical sounds may have been a more common and positive part of the daily environment in which the heifers were kept Že.g., noise of tractors delivering feed.. Also the sounds of humans shouting may have been a sound previously encountered during negative experiences Ži.e., loading prior to transport, handling during vaccinations, branding, etc... The heifers used in this study were beef animals which were not accustomed to handling by humans. The average HR values recorded throughout the experiment were higher than average HR values of lactating dairy cows ŽDeRoth, 1980; Arave et al., 1991. which are generally more acclimated to human voices. On the first day of Trial 2 the average HR for Voice and Clanging were 107.3 " 3.44 and 88.3 " 2.66 bpm, respectively. It is difficult to speculate on the biological significance of a 15–20 bpm difference in HR between the two treatments on day 1. However, to hypothesize that the Voice treatment experienced a greater fear response than the Clanging group seems valid. It is the magnitude of the fear response Žeither mild or severe. which remains uncertain. The HR we recorded were lower on average than the HR recorded for dairy cows held in isolation ŽHopster and Blokhuis, 1994.. Our heifers were not tested in isolation, suggesting the sounds tested in our study were not as alarming as isolation. 4.3. Habituation to treatments The time for cattle to habituate to handling through a chute complex has been shown to occur after three or four experiences ŽAlam and Dobson, 1986; Stookey et al., 1996;

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Schwartzkopf-Genswein et al., 1997a,b.. Habituation to the treatment protocol should lead to a gradual decrease in response over time. The observations seen in this experiment are similar to those in a study done with pigs ŽTalling et al., 1996. in which the pigs became habituated to noise when no danger or threat was apparent to them. The effects of habituation were evident for both treatment groups in each trial ŽTables 1 and 2. based on the pretreatment HR recorded on consecutive days of the trials. The average pretreatment HR for heifers on the first day of Trials 1 and 2 were 95.1 and 97.8 bpm, respectively, while baseline HR on day 5 of Trials 1 and 2 were 83.2 and 75.7 bpm, respectively. Based upon HR data alone, it would appear that the heifers were not as alarmed on the final day of the trials as they were at the start of the experiment. Over the course of the two trials there was no evidence that habituation had occurred based on the amount of movement displayed by the heifers. In Trial 1, while HR showed a gradual decline over the 5-day trial, the amount of movement measured remained unchanged. One explanation for this discrepancy could be that habituation to a previously fearful stimulus may decrease HR, but may not necessarily cause a decrease in movement. For example, immobility may reflect placidness or lack of concern in some individual animals, while it may indicate an intense level of fear in others ŽRomeyer and Bouissou, 1992.. Similarly, movement may be motivated by fear and interpreted as escape behaviour, or it may be motivated by the search for conspecifics and interpreted as social behaviour ŽRomeyer and Bouissou, 1992; Boissy and Bouissou, 1995.. The balance of factors which may have motivated the heifers to move may have shifted from fear on day 1 towards frustrationranticipation on day 5, while the amount of movement overall remained unchanged. The validity of our interpretation that animals initially moved due to fear and later were motivated to move by some other factor is supported by the HR data. Under normal management conditions, beef cattle are not handled as frequently as they were during this experiment and it is unlikely that habituation would occur with infrequent handling. Therefore, exposure to noises during handling may remain novel for beef cattle under typical management conditions. One simple and economic way to reduce noise during handling would be to add rubber padding to areas where metal and metal can strike against each other. Perhaps even more useful would be to avoid shouting when handling cattle.

5. Conclusion It is evident that noise Žsounds of humans shouting and metal clanging. evokes responses indicative of fear in beef cattle based on elevated HR and increased movement. Of the two sounds, the sound of humans shouting appeared to be more alarming than the sound of metal clanging. Habituation to the noises did occur over the 5-day trials, but may not occur with infrequent handling as is typical under normal management procedures. However, steps to reduce noise Žshouting or metal clanging. during handling should help reduce the level of fear experienced by beef cattle.

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Acknowledgements We are grateful to Keri Hudson for her help in collecting the data and Gerry Flannigan for his helpful suggestions during the writing of this paper. We extend special thanks to Brent Burlingham for sound editing and Frank Harrington and the University of Saskatchewan Division of Audio Visual Services for technical advice and equipment loan. Funding for this project was provided by the Western College of Veterinary Medicine through the Interprovincial Undergraduate Student Summer Research Award and the Saskatchewan Agricultural Development Fund.

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