Page 248 - The Welfare of Cattle

WeLfare Issues In feedLot CattLe 225

and maintaining adequate forage levels in the diet (Marti et al., 2016). Vaccines may be useful
in controlling the infectious agents associated with feedlot lameness; however, at this time those
registered for use in North America have been marginally successful (i.e., in the case of foot rot;
Checkley et al., 2005). It should be noted that studies assessing the relationship between reduced
lameness and the majority of mitigation strategies indicated above are lacking in the scientific lit-
erature. Improved diagnosis and targeted treatment protocols as well as continued research focused
on the testing and identification of effective mitigation strategies (based on known risk factors) will
help to reduce the incidence, severity, and relapse rates of lameness in feedlot cattle, ultimately
improving welfare.

Buller Syndrome

The feedlot environment imposes artificial social groupings both in composition and size. Feedlot
pens typically hold between 100 and 300 head of cattle at a time. Under natural circumstances cattle
form stable groups of up to 50 animals which include a mixture cows, bulls, and heifer and bull
calves (Sowell et al., 1999). Consequently, it is not surprising that confinement rearing large groups
of cattle may exacerbate some social problems.
Although it is not desirable to mix cattle between pens, it is common practice to sort finishing
cattle into new groups (pens) based on weight (weight-breaks) and amount of fat cover, several
times prior to marketing, with the ultimate goal of selling more uniform groups of cattle for
slaughter. Several studies have shown that mixing unfamiliar cattle increases aggression and
related injuries and may also limit individual animal access to resources such as feed and water
(Tennessen et al., 1985; Mench et al., 1990).
The buller steer syndrome is a major welfare issue in some feedlots with an annual incidence
between 2% and 4% (Irwin et al., 1979). It is characterized by excessive and sustained mounting of
one particular steer (buller) by one or several other steers (riders) housed within the same feedlot
pen. If appropriate interventions are not put in place the buller steer can suffer fatigue, trauma to its
back and hind quarters, broken limbs and in some cases death (Blackshaw et al., 1997). One study
reported that morbidity and mortality were 2.5 and 3.2 times greater in bullers than other cattle
(Taylor et al., 1997). To the authors’ knowledge, there are no reports of this behavioral problem in
cattle housed on range.
The reported causes of buller syndrome are numerous indicating that its manifestation is
complex and may involve multiple risk factors. These factors include: animal weight, group size and
space per animal, mixing, social dominance, transportation, handling, weather, excessively muddy
or dusty pens, improper or late castration, feeding management (Blackshaw et al., 1997), and the use
of growth promoting implants and how they are managed (improper technique, extra dosing, and
re-implanting) (Voyles et al., 2004; Bryant et al., 2008).
Few studies have been published on this topic—likely because of its erratic nature and the
difficulty in inducing it for study purposes which has hindered the development of successful
mitigation strategies. One of the few studies conducted on the relationship between pen space the
incidence of bullers found that for every 9.3 m increase in pen size bulling was reduced by 0.05%
2
(Irwin et al., 1979). Some recommended management practices to reduce the occurrence of buller
syndrome include: limiting the number of steers within a pen to 200 or fewer, minimizing the
number of different groups of cattle used to form a pen, and implanting at the time of entry into
the feedlot rather than later in the feeding period (Blackshaw et al., 1997). Some producers have
successfully managed the problem by building “hides” which are overhead structures that prevent
mounting and allow the buller to escape from the riders. Another commonly used strategy is the
removal of the buller from its home pen to a smaller recovery pen for some days or weeks before
introducing it into a new pen. It should be noted that none of the strategies described above are
known to eliminate the problem.