We see two schools of thought when it comes to grouping cows. This industry-wide debate centers on social interactions. While the effects of moving are well quantified in dry cow groups, the body of research on moving lactating animals is much smaller.
Some dairies seem to manage multiple groups successfully, while others believe moving cows will cause a loss in production that can never be recaptured. Most literature confounds the effects of a diet change with the social change. The portion that doesn’t still uses animals in group sizes unlikely to be seen in today’s commercial operation.
This past fall, I set up a trial with Dr. Randy Shaver at the University of Wisconsin – Madison to quantify the effects of regrouping mid-lactation cows on a commercial operation. We ran the study in two herds, enrolling more than 300 animals in each. Both herds had stocking densities under 120 percent.
One herd was a Jersey and Holstein x Jersey crossbred herd with pen sizes of 420. Two pens were enrolled for the study. We randomly selected cows between 70 and 200 days in milk, enrolling 10 percent of each pen to the move treatment and 10 percent to a control (no move) treatment.
The other herd was a Holstein herd with group sizes of 70 and five pens were enrolled. The same criteria were used, but we enrolled 10 cows to each treatment rather than 10 percent. After monitoring production for 10 days, the cows assigned to move were swapped between two pens.
Production was monitored for another 10 days after the move. This process was repeated at multiple time points in both herds. Table 1 shares an abbreviated version of the results. We saw no significant, lasting impact on milk production.
So why did this study show negligible effects of regrouping when the effects are so apparent in pre-fresh cows?
It boils down to one word – stress. Regrouping animals in any situation can create stress, and the degree of stress varies tremendously. We need to recognize and take advantage of strategies to reduce this stress.
First, taking an animal already in a high-stress state, such as pre-calving, and increasing her stress load, likely will not have favorable returns.
In lactating groups of increasing size, we have many ways to minimize the social stress of regrouping and potentially capture positive economic returns. Producers commonly move cows to account for breeding status, milking time, somatic cell count, etc., and any of these strategies can be very beneficial. Reducing the stress of a move as much as possible is essential to reaping the benefits desired.
Minimizing the stress of a move is very similar to minimizing the stress of other daily chores on a dairy. First and foremost, cattle handlers should always act in a calm manner. Even when not moving animals, someone running through pens or yelling will have detrimental effects on the animals’ stress levels.
Second, do the job as quickly as possible. If using headlocks, don’t leave animals locked for extended periods of time. If using a sort gate, make sure animals aren’t left in a catch pen without food and water for lengthy amounts of time.
Another management factor to consider is the stocking density of pens. In pens short for bunk or stall space, animals will naturally be more aggressive and the effects of introducing new animals (who quickly find themselves on the low end of the pecking order) may be more profound.
If cows are moving from a low-density pen to one with a high stocking density, the perceived need to fight for their spots will increase their stress. Finally, moving cows in groups rather than individually should help mitigate stress, as they can recognize someone around them and are less likely to be singled out by any boss cows in the new environment.
It is possible to move lactating cows without creating undue stress. That said, I do not recommend moving cows 10 times throughout lactation or feeding a low group. Here are a few common challenges we see when grouping cows.
We can easily have too many moves throughout lactation and increase our labor demands during moving enough to offset efficiencies captured elsewhere. While research is continually coming forward, we still don’t know all of the answers when it comes to physiological demands for milk production and control of intake.
Further, it is very difficult to manage more ingredients and more rations on-farm without having greater losses in feeder efficiencies and ingredient shrink.
The risk of managing by averages is also huge. No different than any other practice, dealing with averages on the dairy creates a lot of room for missed opportunity. For example, your dairy may calve heifers at an average of 24 months old, but if the range is from 19 to 28, you are missing opportunity on both ends – lost production in young animals and feed savings in older animals.
Similarly, we may be moving cows producing 85 pounds of milk and expecting them to continue producing that on a diet balanced for the average 70 pounds of milk within that group. That’s not a very realistic expectation and you may quickly see any feed savings offset by milk losses.
Grouping cows according to different parameters can be good or bad. You may save cost in your diet by feeding more byproduct to low producers, but be careful. You must not lose production, as it will mitigate any savings in diet cost.
You also may be able to take advantage of labor savings by grouping cows with similar characteristics. It all comes down to what works with your management factors, labor and unique farm characteristics. But if done in a stress-free environment, you should not have any lasting, detrimental effects from the social changes. PD