Silence Is Golden

Canadian research indicates a mum crew and a quiet environment makes for less anxious animals at handling time.

Imagine you're eating breakfast one morning and feeling under the weather. Suddenly your spouse sneaks up and smashes a pair of saucepan lids together just behind your head. Welcome to the auditory world of a cow.

Just like humans, what a cow hears affects how she feels; and how she feels affects how she behaves and responds to people. To a large extent, that determines how safely and easily she'll handle.

Recent research suggests environmental sound has considerable influence on the behavior and physiological response of beef cattle. And that has important implications for handling and managing them.

Cattle are able to hear a much wider range of sound frequencies than humans. Most young adult humans can hear sound in the range of 20 to 20,000 Hertz (Hz). In middle age, the upper frequency we can hear normally declines to 12,000-15,000 Hz.

For comparison, the strings of a piano produce musical notes from 27.5 Hz to 4,186 Hz. A “silent” dog whistle produces sounds between 5,400 and 12,800 Hz; the upper value would be barely audible to many people. The frequency hearing range of a cow, however, is from around 16 to 40,000 Hz.

The environment is full of sounds inaudible to humans but clearly audible to cattle. Cattle conceivably should be able to hear both the low-frequency rumbles of African elephants and the ultrasonic screams of flying bats. In fact, some evidence suggests cattle may use very low frequencies in vocal communication.

Assessing cattle's response to different noises

Recently, University of Saskatchewan researchers conducted a pair of experiments to assess cattle's response to different noises during handling. The first study measured cattle response to the types of noise typically encountered while moving through a chute.

We began by making two sound recordings.

  • First, I walked through the chute with a steel bar, beating the metal side rails and head gate as someone followed with a microphone.

  • Next, a few of us crowded around the microphone and sounded off with the kinds of vocal effects often used to persuade cattle to move up in a chute.

In the university's recording studio, we remixed the sounds on a new tape. This enabled us to play back either clanging noises or voices alone, or both mixed together, and all at the same overall volume.

We tested the effects of sound on beef heifers by measuring their heart rates, using wireless telemetry as they stood on a scale platform connected to a device measuring their physical activity. We exposed 15 heifers to the mixture of mechanical and vocal noise played through loudspeakers. Meanwhile, another 14 heifers were exposed to a period of silence once/day for five consecutive days.

The noise-exposed heifers showed elevated heart rates and more movement compared with the silent control group. This fear response didn't surprise us, but we wanted to know which sound component was more responsible for the increased agitation.

In a second trial, we subjected half of 30 additional heifers to only the chute-banging sounds. The other half was exposed to only human voices. Both were played at the same intensity.

Animals exposed to voices seemed more unsettled — as indicated by higher heart rates and more movement — than those exposed to banging noises.

What is it about the human voice that triggered such a fear response? One possibility might be cattle's perception of the urgency conveyed by the handler's voice.

We tested this notion in a follow-up experiment. Again, our team visited the recording studio. This time, we recorded individual tracks on which we shouted and cursed at imaginary cattle, attempting to reproduce the tone of voice often used to cajole cattle into motion.

Next, we listened to those tracks and transcribed the vocal expressions into short scripts. We then recorded ourselves reading those same words in the most neutral, uninterested and uninflected voices possible. Again, the tracks were matched for intensity so both types of recording could be played at the same volume.

Both recordings were played back to the heifers. There was no difference, however, in heifer response to the words when spoken with the intent to move the cattle or when spoken in a neutral manner.

The results seem to imply the sound of the human voice is inherently upsetting to beef cattle. What you say and how you say it appears to be immaterial. Thus, heifers presumably wouldn't be particularly calmed by a deliberately gentle, reassuring tone of voice — a hypothesis yet to be tested.

As a member of the Western College of Veterinary Medicine's animal behavior research group for 12 years, I've been involved in many beef cattle behavior and handling studies. These studies have made us much more aware of sound's impact on animals.

In handling cattle, we do it as quietly as possible, and it helps. I'm convinced cattle behavior in chutes and head gates is more dependant on people behavior than genetics, previous experience, weather, time of day or any other factor.

Sound during handling is an important and usually overlooked variable. However, it should be relatively easy for most operators to improve in this regard.

Just turn off the radio and unnecessary machinery. Utilize as few people as needed in the handling area. Minimize any mechanical noise by using tape or rubber cushions to prevent clanging metal. But, most importantly, eliminate shouting, and even talking, as much as possible.

Jon M. Watts is an animal behavior research associate in the University of Saskatchewan's Western College of Veterinary Medicine, Saskatoon.

TAGS: Management