Blog post written by Elise Shepley.
I started my PhD thinking ‘I’m going to investigate the effect of exercise in dairy cows’. In fact, that might have been exactly what I said during my first advisory committee meeting. I presented my detailed plans on how I was going to look at different housing systems that I thought offered different levels of exercise and see which offered the most benefits to the cows, to which the reply from my committee was ‘are you really measuring exercise?’. Thus, an overarching objective of my doctoral career became clear: re-examine the way in which we define the provision of exercise in dairy cows through an exploration of the quantitative and qualitative ways in which it is presented in existing literature.
Controlled Exercise Studies and Cow Fitness
To start, when I think ‘exercise’, I think movement, a lot of sweat (…maybe some tears…), and, eventually, improved fitness. Some of the early studies of exercises in dairy cattle also saw the improvement of fitness as a potential outcome of increasing the level of movement and physical exertion of the cow, walking the cows at fixed speeds and distances to understand the effect that this increase in exercise has on the cow and how much was needed to yield such results.
This offered a good deal of insight on the connection between physiological effects of exercise and the level of exercise itself on the cow. Walking cows led to lower increases in red blood cells, respiration, and heart rate by the end of the study for exercised cows as a result of the increased fitness of the animal. Benefits even extended to improvements in reproductive capabilities, including a decrease in days open, fewer insemination attempts, and reduced instances of post-calving diseases reported.
The issue, however, is the extrapolation of this application of exercise to real-life. Asking a producer to take his herd for daily walks isn’t exactly a practical method for producers to use to exercise their cows. What we can ascertain from these studies is the key factor associated with the ‘bodily exertion’ that led to the improved fitness in these early studies: the level of locomotor activity exhibited by the cow.
Measuring Locomotor Activity Quantitatively Through Technology
The development of new technologies for the dairy industry has provided researchers with the opportunity to determine the amount of locomotor activity that the cow expresses in different housing environments.
For example, step data from pedometers show us that tie-stalls, the system associated with the greatest level of restriction of cow movement, yields a lower level of step activity than other indoor systems (see table below). The addition of outdoor access and or pasturing of cows, however, yields even greater step activity. Moreover, global positioning data (GPS, top left) shows us that, not only are the cows exhibiting higher numbers of steps on pasture, but that they are also walking considerable distances to do so, largely due to the expression of grazing behaviors in these environments (~ 66% of total distance traveled).
Housing Characteristics: Qualitative Aspects and Locomotor Activity
Within these different housing systems, characteristics in the cow’s environment can have a large impact on the cow’s locomotor activity. Aspects like the quality of the walking/lying surface, whether the housing uses stalls or is more open, and the amount of space a cow is provided will all impact her locomotor activity as well related health and behavioral outcomes.
Flooring is a very important factor, influencing the way the cow walks and her willingness/confidence to walk. Cows are evolutionarily designed for pasture, which offers a soft, compressible surface with good traction for the animal when walking, but changes to indoor housing can yield similar results. For instance, rubber mats have been found to simulate pasture flooring, with locomotor activity and stride length found to be much greater compared to concrete. There is a caveat, though, as this flooring’s efficacy lies in its management, with wet and or manure covered floors leading to reduced ease of movement, joint stiffness, and a higher risk of slips and falls.
While not improving on the level of locomotor activity recorded, deep-bedded packs may offer an even more comparable flooring to pasture, with greater compressibility and similar traction as rubber mats reported, but with less risk of slipping. Not only can these systems improve gait and confidence when walking, but they also have the added benefit of a more comfortable lying surface to improve lying time, comfort, and ability to transition between standing and lying, all of which may translate to better leg health.
Did you know you can also create deep-bedded packs in existing stalls using bedding keepers? Click HERE to learn more from this study!
Space and Stall Hardware
Tiestall and freestall housing systems are notable for their use of stalls as a standing/lying area for the cow, delineated by stall hardware including a manger wall/brisket board and tie-rail at the front, dividers on the side, and often a depressed gutter area to the cow’s rear. For tie-stall cows, in particular, this minimizes movement opportunities in all directions. While the cows in freestalls have other areas in which they can move, the stall still inhibits ease of movement during the rising and lying-down actions of the cow, leading to higher collisions with the dividers when lying down and the tie-stall when rising in both systems. Releasing cows into a stall-free alternative reduces these collisions and also may also increase locomotion related to non-maintenance behaviors like exploration and socialization
Space also contributes to the exhibition of these behaviors, as well as overall step activity. In fact, space, more than stocking density, was previously reported to have a greater impact on how much the cows moved within their housing system. The same idea extends to pasture, with larger paddocks encouraging cows to walk further while grazing and engaging in other activities than smaller paddocks.
This increase in space has the added bonus of improving on the cow’s ability to lie comfortably as well, with cows in wider tiestalls (see the study HERE) and in loose pens (see the study HERE) exhibiting greater diversity in their lying postures than in their counterparts housed in single-width tiestalls. This has the potential to increase joint health and, thus, improve overall gait and locomotor abilities!
Outdoor Access and Locomotor Activity: An Effective Addition to the Cow’s Housing?
A number of studies equate outdoor access, be it through exercise yards or pasture, to exercise. Outdoor access can, indeed, increase locomotor activity when compared to just indoor housing alone, but there are a number of factors that must be considered when utilizing this method to increase locomotor activity in dairy cows. Firstly, how long (duration of time/d) and how often (frequency, no. of times/wk) can impact the resulting health and welfare outcomes. For instance, 1 h/d in an exercise yard was suggested to be sufficient for expression of behavioral and locomotor needs in tiestall-housed dairy cows whereas 2-3 h/d may be needed to improve leg health, decrease hock injuries, and improve issues around calving. In fact, outdoor access frequencies of less than 3 d/wk increased risk factors related to poor welfare, included risk of lameness, injury, and restricted resting. Likewise, the frequency of access is important, with shorter durations and more frequent access to the outdoors proving more advantageous for not only cow health, but also in reducing frustration behaviors that can result from long periods of restriction between periods of outdoor access.
Perhaps the biggest barrier to the efficacy of outdoor access as a means to elicit increased locomotor activity in the cow is the fact that it is largely dependent on the individual cow to engage in activities related to movement when provided this addition to her housing environment. Cows that display higher levels of locomotor activity are likely to do so in any environment in which they are placed, and visa versa for low activity level cows. Moreover, when providing free access to the outdoors, it is necessary to consider the cow’s preference go outdoors versus her preference to stay inside. This can be based on the nutritional needs of the animal, her physiological condition, and her general health (e.g. lame or not). Additionally, cows with more experience outdoors are more likely to utilize this space when provided. Taking individual cow needs into consideration will improve the efficacy out providing outdoor access to cows and help target cows that may require methods for increasing locomotor activity to attain the resulting benefits to the cow.
Movement Opportunity: Redefining ‘Exercise’ in Dairy Cattle
If we break it down, exercise, as described in the literature, includes 1) the level of physical exertion a cow experiences when engaging in controlled locomotor activities, 2) the level of locomotor activity performed by a cow in her given environment, and 3) the provision of a housing system and characteristics within each system that facilitates ease of movement of expression of locomotor activity. Locomotor activity that defines ‘exercise’ is either hindered or promoted by the housing system in which the cow resides and the characteristics of said housing system. In reality, the cow’s housing provides cows with the opportunity to move – movement opportunity that is provided by the producer through the cow’s housing and or management, but that is ultimately dependent on the individual cow to utilize as she needs or prefers.
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