Normal and pathological mounting (bulling behaviour) in feedlot steers
J.L. Clavelle and J.M. Stookey
Large Animal Clinical Sciences
Western College of Veterinary Medicine
University of Saskatchewan, Saskatoon, SK
3. Peak mounts received by bullers ranged from 18 mounts/10 min to 34
mounts/10 min and each buller showed dramatic variation in mounts/10 min
during subsequent observations (Fig 3a-g).
3b
30
10
10
5
5
0
0
M
M
M
Time of day (2400 hrs)
20
15
15
10
10
0
18:00
M
M
35
30
10
10
5
5
0
0
10:00
3f
14:00
15
13:30
15
13:00
20
12:30
20
9:30
25
9:00
25
8:30
b)
3e
9:30
30
35
9:00
Buller Steer
5
M
17:30
Riders
17:00
0
M
11:30
20
11:00
25
10:30
25
3d
10:00
30
9:30
30
35
3c
9:00
35
5
35
30
3g
25
Fig. 1 a) A buller steer being mounted and surrounded by several steers and
20
15
b) Buller with characteristic mud pattern over tailhead, rump and flank with
hair loss over the tailhead.
10
5
15:00
14:00
13:00
12:00
11:00
M
10:00
0
9:00
a)
18:00
15
17:30
15
17:00
20
18:00
20
17:30
25
17:00
25
10:00
30
35
3a
9:30
35
16:30
The Buller steer syndrome is characterized by the repeated mounting of a
steer (referred to as the buller) by a group of steers (known as the riders) that
persistently follow and perform the mounting behaviour. Because bullers may
suffer loss of hair, trauma to the rump and tail head, exhaustion, broken
bones, or may even die from injuries, treatment (removal from the pen) is
necessary. The annual incidence of buller steers is reported to be between 2
and 5% of all feedlot steers, however the incidence per pen is variable,
ranging from 0.0 to 11.2% on a per pen basis (Taylor et al., 1997).
Joseph M. Stookey
16:00
Introduction
Number of mounts
Jean L. Clavelle
Fig. 3a-g Number of mounts received by the buller steer during each 10
minute observation period are shown (individual graphs represent individual
bullers). ‘M’ represents missed observation. Yellow bars indicate 10-min
Objective
To describe buller mounting behaviour and normal
mounting behaviour (not associated with bullers) in
a large group of feedlot steers
observations when bullers met “True Buller’ criteria.
4. Peak mounting occurred at a different time of day for different buller steers
(Fig 4).
10
9
Materials and Methods
8
7
Animals: A total of 14 pens of beef steers (average pen size of 206 animals
per pen) from a large commercial feedlot in central Saskatchewan were used.
Methods: In the absence of bullers, 12 pens were observed in a predetermined order for a 4-min period each daylight hour. The total number of
mounts was recorded to determine the frequency of mounting in the absence
of a buller.
6
5
4
3
2
1
0
730
830
930
1030
1130
1230
1330
1430
1530
1630
1730
Time of day (2400 hrs)
‘True Buller’ steers, as determined by our definition, received a minimum of 7
mounts and 10 chin rests and were followed by at least 7 riders during 4
minutes.
Upon finding a ‘True Buller’, 4-min observations of each pen were suspended
in order to observe the buller steer. Continuous observation was used to
record buller mounts and continued until sunset, the buller was removed from
the pen, or until the buller received no mounts for 20 minutes.
Fig. 4 Each line represents the period of time individual bullers met ‘True
Buller’ criteria (bold line) and when buller received mounts although did not
meet ‘True Buller’ criteria (thin line).
5. The identification and removal of bullers may be dependent on the time of
arrival of pencheckers. Seven out of 10 buller steers were not removed since
mounting had either ended or not yet started by the time feedlot personnel
entered the pen that day. This has serous implications for the welfare of
unidentified bullers and presents a problem for treating this condition.
Results
1. Two peaks in mounting were observed in pens without bullers; one during
mid-morning and one during late afternoon, prior to sunset (Fig 2).
Mounting behaviour in the absence of a buller shows a pattern similar to
the eating pattern and general activity of cattle.
Mounting frequency is episodic, so the identification and removal of bullers
is dependent on the time pencheckers enter the pen relative to peaks in
buller mounting.
5.0
4.5
4.0
Num ber of m ounts
Conclusions
3.5
3.0
2.5
2.0
1.5
References
1.0
0.5
0.0
700755
800855
900955
10001055
11001155
12001255
13001355
14001455
15001555
16001655
17001755
18001855
Time of day (2400 hrs)
Fig. 1 Mean (+ SEM) frequency of mounts within a pen of feedlot steers, while no
buller steer was present.
2. A total of 10 buller steers were identified during the study that met the
‘True Buller’ criteria (Fig 3a-g shows 7 of the 10 bullers).
Taylor, L.F., Booker, C.W., Jim, G.K. and Guichon, P.T., 1997. Aust. Vet. J. 75,
45-51.
Acknowledgements
This research received financial support from the Agricultural Development
Fund. We would like to thank the management and staff of Goldenhill Cattle
Co. for making their animals and facilities available for this project.