People expect cows to graze. Pastoral scenes of cows at pasture are used by many marketing groups to sell milk products. Yet the reality of our dairy industry in North America and many other parts of the globe is very different, with a shift toward larger herds, housing and more intensive management.
Proponents of grazing argue that the cow is managed in a more natural state and is free to carry on all normal behaviors – which obviously include grazing. They will point to significant literature that identifies the obvious problem of housing, which limits natural behavior and is associated with increased production-related diseases such as mastitis and lameness.
However, the realities of grazing are also clear to those that work with such herds when you expose cattle to the elements. Such elements include rainfall in the winter, early spring and late fall; muddy tracks and frozen teats; heat stress and lack of shade in the summer; water-delivery challenges; and fly problems. There are also environmental concerns related to managing runoff that preclude grazing in certain areas.
We believe housing is essential for the management of the dairy cow in most climates. Even most grazing herds only graze during the summer months and house during the winter.
Correctly designed and built facilities, when coupled with excellent herd management, result in very high standards of well-being and deliver much increased productivity, creating a sustainable solution to the global food supply shortage. However, we would be remiss not to consider the possibility that some access to the outdoors may be good for the cow.
One study has shown that given 24-hour access to pasture, locomotion score appears to improve by one point over a short four-week period, and this improvement occurred despite reduced lying time per day at pasture compared to freestall housing.
When given the choice between life at pasture and life in a freestall barn, cows choose both. Several studies have now shown that when given free choice, cows prefer to be at pasture during the night and indoors during the day. Rainfall and production level favor the choice to move inside the barn.
Interestingly, cows appear to maintain this preference even under conditions of overstocking inside the freestall, suggesting that there are actually some benefits to housing perceived by the cow.
So can we provide pasture access and maintain production and health in our housing systems?
A recent study demonstrated that for heifers and cows given overnight access to pasture from four weeks before to eight weeks after calving, compared to freestall housing continuously, production was maintained at around 84 pounds of milk per cow overall with no differences between the groups.
Unfortunately, this study also demonstrated no lameness benefit of overnight pasture access – so while overnight pasture access was managed to reduce the impact on production, there was little benefit health-wise. However, two recent studies, including one of our own here in Wisconsin, have shown that pasture access is a significant factor influencing lameness prevalence.
In Northeast dairy herds, lameness decreased with deep bedding and pasture access during the dry period, and in a group of high-producing Wisconsin freestall herds, 9 percent allowed the high group of mature cows pasture access, and this practice was associated with a beneficial effect on lameness.
Life in an optimally designed deep, loose-bedded freestall facility with free access to TMR can meet the vast majority of the needs of the cow and maintain high levels of production and well-being. Not every farm needs to allow their cows to have pasture access. However, it is clear that cows enjoy some access to the outside, and in some situations, there may be a health benefit.
We are working on barn designs where there is outside access built in for lactating cows and dry cows – to be used when appropriate as weather conditions are favorable. For barns with comfort issues such as uncomfortable mat or mattress stalls, allowing strategic periods outside the barn may have a positive impact on lameness prevention and recovery.
At this time, we are cautious to recommend pasture-lot access for early lactation groups since this may increase the risk for ketosis and potentially limit production. PD
Nigel Cook is currently chair of the Department of Medical Sciences at the University of Wisconsin – Madison School of Veterinary Medicine and manages the Dairyland Initiative.
