Page 107 - The Welfare of Cattle

84 the WeLfare of CattLe

speculation that auditory abilities have been negatively impacted by evolutionary adaption but an
analysis of sound localization of species divided into groups based on domestication status indi-
cated that domesticated animals are not less accurate localizers than wild animals (R. S. Heffner &
Heffner, 1992b). Less-accurate sound localizers tend to be prey animals as opposed to predatory
species. Animals that are poor sound localizers also tend to have their most acute vision in a hori-
zontal streak providing them with a wide range of vision. It is speculated that cattle don’t need to
be good sound localizers because by the time they hear a predator approaching on the horizon, they
have already seen the approach (Phillips, 2002).

Do Cattle hear What their human Caretakers hear?

The ability to hear high-frequency sounds is characteristic of the mammalian auditory system
(Heffner & Heffner, 2008); high-frequency meaning above 10 kHz as that is the upper limit of other
animal families. Researchers had observed that generally smaller mammals were more adept at
hearing high frequencies. To use the binaural spectral difference discussed above to locate sounds,
it is necessary to have a head large enough to attenuate the sound and change its intensity level at
each ear. Heffner and Heffner (2008) have shown a significant negative relationship (r = −0.79,
p < 0.0001) between head size and high-frequency hearing for over 60 species. Although cattle have
a bigger head size than humans, they can hear higher frequency sounds than humans can but do not
hear particularly high frequencies as compared to other species such as cats and mice (Heffner &
Heffner, 2008).
Heffner and Heffner (1983) determined that cattle have a well-defined “best frequency” for
hearing at 8 Hz, with a range from 23 to 35 kHz. Generally, it has been demonstrated that ungulates
are not sensitive to high-frequency sounds as compared with other mammals. The audiogram devel-
oped for cattle indicates that cattle are sensitive to low-frequency noises, more sensitive than humans
and horses (Heffner & Heffner, 1983). Cattle vocalizations average between 50 and 1,250 Hz (Kiley,
1972). Studies have been conducted on cattle exploring vocalizations in response to various manage-
ment procedures such as painful procedures, weaning, and isolation (Boissy & Le Neindre, 1997;
Schwartzkopf-Genswein, Stookey, & Welford, 1997; Watts & Stookey, 1999). There is opportunity
for further research relating the frequency of cattle vocalizations in response to certain stimuli in
relation to the cattle auditory system.

hearing and the human–Cattle Interaction

Understanding the auditory sensitivity of cattle is helpful because it provides handlers and man-
agers with some insight as to what types of sound may be aversive to the cattle they are working
with. Typically, animals do not like loud sounds—this has been documented both in research stud-
ies and publications on how to handle animals humanely. Grandin (1980) discussed the impacts
that noise can have on cattle handling, particularly noise associated with equipment (e.g., motors
from hydraulic chute) and handlers, and recommends that for optimum handling, noise should be
minimized. It is important for animal handlers to recognize that their voices alone can provoke fear
or stress responses in cattle when they are moving them. Some studies have indicated altered heart
rate and behavior in cattle indicative of a fear response when exposed to recordings of animal han-
dlers’ voices (Waynert, Stookey, Schwartzkopf-Genswein, Watts, & Waltz, 1999). The mobility of
animals’ pinnae varies from no mobility in humans to 180° pinnae movement in horses, with cattle
on the same end of the spectrum. It is difficult for humans to comprehend the benefit and/or result
of pinnae movement to localize sound because human pinnae are not motile (Heffner & Heffner,
1992a). Cattle, however, do move their ears and this is noticeable when working with cattle. Reading
cattle’s ears is one way to understand what they may be listening to or distracted by. It is important
to note though that although an animal may have motile ears, it does not necessarily mean they are