Another Reason To Give Cows Pasture Access

While in certain countries such as Finland, Norway, and Sweden, full-time indoor housing of cows is banned, keeping cows indoors around the clock is a common practice in many other countries. For example, in Denmark, Greece, and Poland, less than 25% of dairy cows had access to pasture in 2019. Access to pasture has many advantages for cows such as longer opportunities to lie down, more space, and access to a softer surface. Cows also tend to choose pasture access when given the choice.

In addition to physical health benefits, pasture access promotes cows’ natural behavior. However, its effect on their emotional well-being is not very clear. Just like humans, animals’ emotions influence their judgment, and positive emotions result in a more optimistic judgment about ambiguous situations. This is called a “judgment bias.” Researchers measure judgment bias to assess animals’ psychological state.

To assess the effect of pasture access on dairy cows’ emotional state, researchers recruited 29 Holstein-Friesian cows in Northern Ireland who were housed indoors for eight weeks before the start of the experiment. The cows were divided into two herds. Researchers gave overnight pasture access to one group and full-time indoor housing to another group. Then, they repeated the experiment for another 18 days, this time swapping the groups. Swapping the groups permitted researchers to test the effect of both housing statuses during the same period and test each cow’s psychological state in both situations.

Researchers used a spatial judgment task to assess how cows behave in each situation. They placed a rewarded bucket containing food in one location and an unrewarded empty bucket in another location. Cows learned to approach the bucket with food and avoid the empty one. Next, the researchers placed three other empty buckets, which they referred to as probes, between the rewarded and unrewarded buckets. Both groups of cows were tested to see how long it took them to approach the probe buckets, and how often they did it. 

Before the experiment, the researchers assumed that cows who feel better emotionally will be more optimistic to find food in probe buckets and will approach them quicker and more frequently compared to cows who feel emotionally worse. However, contrary to what they expected, cows who had pasture access and those who didn’t acted the same toward the probe buckets regardless of their housing status.

In addition, to their surprise, the cows with pasture access reached out for the rewarded bucket slower (7.12 seconds) and less frequently (47.8% of the time) compared to cows who were kept indoors full-time (6.42 seconds; 53.2% of the time). The researchers argued that cows with pasture access possibly showed less interest in the rewarded bucket because their environment was already rewarding and induced a positive psychological state, thus making them less interested in the reward.

It is important to note that other factors may also explain these findings. For example, cows who have access to pasture may be less food-motivated because they have access to food for a longer period compared to indoor cows who need to wait for grass silage to be delivered. Pasture access may also improve cows’ emotional state while they spend time in the pasture and not after they go inside. Lastly, it is possible that the designed judgment task did not successfully measure the emotional states of dairy cows.

Despite these possibilities, dairy cows prefer to spend time in pasture when given a choice and are more comfortable in pasture compared to indoor cubicles. Therefore, it is plausible that cows with pasture access show less interest in the rewarded bucket because they live a happier and more rewarding life compared to cows housed indoors. In summary, it appears that pasture access improves the emotional state of dairy cattle compared to full-time indoor housing.