Page 246 - The Welfare of Cattle

WeLfare Issues In feedLot CattLe 223

both (Mitlöhner et al., 2002; Kendall et al., 2007; Sullivan et al., 2011). In order for producers to bet-
ter manage cattle during hot weather, it would be beneficial to provide them with a clear definition
when (at what temperature and humidity levels) cattle may be at risk of heat stress. Unfortunately,
the determination of such a threshold is difficult if not impossible due to large variations in factors
such as animal acclimation and individual differences in heat sensitivity as well as the measure of
heat load used (ambient temperature, temperature–humidity index, heat-load index) leading to the
conclusion that animal responses such as high respiration and open mouth panting would be more
useful than a single value of heat load (Brown-Brandl et al., 2003; Gaughan et al., 2010). There is
currently a lack of information regarding the amount of shade required per animal relative to pen
density, the frequency, and duration of cattle handling as well as the type and conformation of shade
used, the type of sprinkling and availability of water through space (Tucker et al., 2015).
Muddy conditions are known to increase infectious (footrot, digital dermatitis) and injury-related
(due to slippery condition) lameness (Stokka et al., 2001) reduce weight gain (Morrison et al., 1970) and
locomotion (Degen and Young, 1993) and increase energy demands (Dijkman and Lawrence, 1997)
as mud acts as a medium for heat loss. Cattle housed in outdoor lots were found to have more dry
mud and manure adhering to their hair coats (tag) than those housed indoors (Honeyman et al., 2010)
which could potentially reduce the isolative value of the hair and increase the chance of cold stress.
Some studies have reported increased indicators of stress such as reduced body temperature and
increased white blood cell counts and elevated cortisol and thyroxine levels in cattle exposed to mud
compared to those that were not (Tucker et al., 2007, Webster et al., 2008), while other studies have
found no differences in measures of immune competence or stress levels (cortisol response) in cattle
housed in dry versus muddy pens (Wilson et al., 2017).
Strategies recommended to reduce the negative effects of mud include regular pen cleaning,
provision of bedding during wet periods, adequate feedlot drainage, and dirt or straw mounds
within each pen that provide a dry area where cattle can lie down (NFACC, 2013). Currently little
information is available regarding the appropriate amount of dry lying space needed for each animal.
Adequate lying space is likely a challenge for cattle housed in pens containing 200 animals or more.

Lameness

Although it is unlikely that the incidence of lameness in feedlot cattle has increased over the
past 30 years, its acknowledgment as a major health and welfare issue in feedlot cattle has only
recently been recognized (Schwartzkopf-Genswein et al., 2012a; Tucker et al., 2015; Marti et al.,
2016). Lameness is characterized by a change in normal gait resulting from pain or discomfort
associated with hoof and leg injuries, or disease (Greenough, 1997). The main and obvious reason
that lameness is a significant welfare concern is its association with pain. Another welfare concern
is the reduction or complete curtailing of an animal’s ability to access feed and water, seek shelter,
or escape from predators or dangerous situations resulting from reduced or loss of lost mobility
(nonambulatory).
Information regarding the prevalence of lameness in feedlot cattle as well as the identification
of the most common types of lameness is minimal. An older survey assessing lameness in feedlots
in the mid-western United States found that 16% of all feedlot health issues were attributed to lame-
ness and lameness accounted for 70% of all non-fit sales cattle (Griffin et al., 1993). The 2001 USA
Beef Quality Audit reported that 31.4% of the cattle observed during lairage (prior to slaughter)
were lame (Roeber et al., 2001). A pilot study conducted in the pens of a small number of Alberta
feedlots found lameness prevalence to be between 32.8% and 52.8% (Tessitore et al., 2011). A recent
unpublished Canadian study on the prevalence and characterization of lameness in feedlot cattle
confirmed that lameness is an important disease in Canadian feedlots accounting for 30% of all
health problems: only second to respiratory disease (40% of all health problems) in terms of its wel-
fare impact (Marti et al., 2016). This same study reported that a high percentage (15.25%) of those