Page 355 - The Welfare of Cattle

332 the WeLfare of CattLe

experience heat stress in extreme conditions. Currently, management is the most important element
in reducing the downstream effects of heat stress. Various engineering solutions have been utilized
to mitigate the negative impact of heat stress on modern dairy farms. Shade structures, sprinklers/
misters, fans, and/or combinations of all three are the most common methods of heat abatement
(Ortiz et al., 2010; Calegari et al., 2012; Anderson et al., 2013). A study by Kendall et al. (2007)
demonstrated exposing cows to just 90 minutes of shade and sprinklers in the holding pen prior to
milking reduced their respiratory rate by 67%. Such drastic improvements certainly merit greater
attention by researchers.
In extensive production systems, cattle spend much of their time outside of controlled barn envi-
ronments, which may place them at greater risk for heat stress. Shade structures, whether artificial
or natural, offer an opportunity for heat-stress mitigation in these more extensive circumstances.
Shade use increases with the heat load index and cattle that seek and utilize shade exhibit decreases
in respiratory rate, panting score, and lower rectal temperatures (Veissier et al., 2018). Even in
temperate climates, cattle with access to shade tend to have increased milk production levels (Van
Laer et al., 2015), yet it is still unclear whether this difference is due to changes in feeding behavior,
shifting metabolic demands, or some combination.
Confinement systems have the advantage of constant shade, but shade alone may not be suffi-
cient to eliminate all the negative impacts of heat stress (Ortiz et al., 2010). Less common practices,
such as air conditioning and conductive stall cooling, offer additional effective means of heat abate-
ment (Collier et al., 2006; Ortiz et al., 2015), but are not yet economically feasible for most farms.
Extensive systems can also benefit from engineering solutions. Providing very brief access to shade
and sprinklers can result in lower body temperatures lasting up to 4 hours (Kendal et al., 2007).
Regardless of production system, producers and their cattle stand to benefit greatly from improved
heat abatement strategies.
Although the effects of extreme temperatures on cattle behavior are mostly due to heat stress,
cold stress can and does occur as well. These conditions are especially problematic for extensively
reared cattle, but also impact cattle housed indoors in insulated barns located in colder climates.
One study found that at −19°C, cattle in free stall barns had increased feed intakes, but decreased
milk production, likely in response to increased metabolic demand for temperature maintenance
(Broucek et al., 1991). Even under relatively mild temperatures, prolonged exposure to wind and
rain substantially impacts cattle behavior. In these conditions, cows may spend as little as 4 hours
lying down (Tucker et al., 2007). Not unlike heat stress, cattle do possess some innate ability to
respond to cold stress. In extremely cold conditions, they will deposit larger amounts of subcutane-
ous and intramuscular fat compared to cattle housed indoors (Mader et al., 1997). Clearly, there is
a great need for additional research exploring the effect thermal conditions have on cattle welfare.

CONCLUSIONS

In this chapter, we have discussed how various features of dairy housing systems impact the wel-
fare of lactating dairy cattle. Perhaps unsurprisingly, housing systems that provide cows with soft,
clean, dry, cool environments, and the ability to move freely and interact with others, tend to lead
to better animal welfare. However, these factors are not the exclusive property of either extensive
or intensive systems. Well-managed intensive systems are capable of achieving welfare outcomes
comparable to those found in more extensive systems whereas extensive, pasture-based systems are
subject to a number of unique welfare challenges (e.g., weather extremes, parasites, nutritional defi-
ciencies, etc.). It is our hope that future research will move beyond system-level comparisons, which
necessarily obscure important details, and instead focus on the impact specific features of different
housing systems have on animal welfare. If for no other reason, this would lead to more nuanced
and informative discussion about the specific strengths and weaknesses of all systems.