Last summer, the milking herd at MSU’s Kellogg Biological Station Pasture Dairy Research and Education Center (PDREC) moved into a new freestall barn, equipped with two robotic milkers.
We collected data on the cows’ responses to being milked by the new system. The information allowed us to evaluate how well cows adjusted to being milked by robots.
In case you were wondering
Why is it important to understand how (or if) cows adapt to being milked by robots? As many of you know, stress during milking can inhibit milk letdown, which can reduce milk yield and could lead to health problems such as mastitis.
Animals can experience stress for a number of reasons, including being introduced to something new, even if this new thing is not particularly painful or frightening. And since being milked by a robot would be new and different, even for an experienced milking cow, it could cause her to experience stress and inhibit her milk letdown.
In theory, there are several reasons robotic milkers should provide a lower-stress milking environment compared with a conventional milking parlor.
First, a cow can choose when and how often she wants to be milked, setting her own milking schedule.
Second, a cow doesn’t have to spend time waiting in a crowded pen outside the parlor before each milking.
This should translate into less time away from feed, water, and stalls to lie in, and also into less bullying by other cows.
Robotic milkers also remove humans from the picture, which for more timid or fearful cows, could be a good thing.
And, last but certainly not least, the cow receives some concentrated feed while she is being milked by a robot. All of these elements translate into an environment with less stress, more reward and more control for the cow, which for all animals, including dairy cows and humans, are typically good things.
But as we mentioned previously, when a cow is first milked by a robot, it is a new and possibly stressful experience. A cow may need some time to adjust to being milked in a different environment, with different equipment, before she can learn to enjoy the theoretical advantages to robotic milking.
If she adapts quickly, the change from one system to another will probably not have a big effect on her productivity and health. If she does not adapt, or adapts slowly, the consequences could range from a drop in production, to a cow that becomes sick more easily, to a cow that may need to be culled from the herd.
What we did
Our study consisted of observing 75 lactating Holstein cows at PDREC as they made the transition from a double-six herringbone parlor to a Lely Astronaut A3 Milking System.
Prior to the transition, PRDEC cows were milked three times a day in the parlor and were managed in three groups (first-lactation cows, multiparous cows, and special-needs cows).
Following the move, the herd was divided into two groups, balanced for parity and stage of lactation; each group had access to a single robotic milking machine.
To go about measuring how well the cows adapted to being milked by the new robotic system, our study measured the number of times cows vocalized, defecated or urinated (elimination), stepped and kicked while in the robots.
We began our observations starting with each cow’s first milking (day 0) by the new robots. We continued to collect data for 32 days. We also measured milk yield over the same time period.
We predicted that the cows would adapt quickly to the robotic milkers, and that as they became more comfortable in their new milking environment, they would show fewer stress-related behaviors while being milked.
What we found
During their first robotic milking (day 0), the cows vocalized, eliminated, stepped and kicked frequently, suggesting that they did not initially like being in the robotic milking stall or being milked by the robot.
However, in less than 24 hours, stepping and kicking prior to teat attachment dropped and vocalizing and eliminating in the robot stalls nearly disappeared ( Figure 2 at left & Figure 3 below).
The rapid decline of these stress-related behaviors could be due to the cows becoming more comfortable with the milking stall and robotic milking equipment and process, including the movement of the robotic milking arm and teat cups.
The cows also could have become more focused on eating grain in the robot’s feeder and less focused on the actions of the robotic arm.
Curiously, steps and kicks after teat attachment to the milking cups (i.e., during the milking process) increased between day 0 and 32.
There are a number of possibilities as to why this may have happened, although it is impossible to accurately identify a single answer without additional research.
During the first month, the new barn’s manure scrapers were not working well, leading to a large amount of manure in the barn and consequently a large number of flies. We were unable to discriminate between steps and kicks related to fly avoidance versus steps and kicks linked to discomfort with the milking process.
Another possible reason the cows kicked more with the robots is the difference in pulsation ratio between the old conventional parlor and the robotic system.
The parlor milking system used had a pulsation ratio of 60:40, while the Lely robot milks at a pulsation ratio of 65:35. The difference in milking and resting ratio could have led to some discomfort during milking as the teats adjusted to the change.
However, we did not inspect teats at the time, so it is impossible to know if the discomfort was a result of declining teat end condition.
Lastly, the discomfort during milking could be due to cows’ being uncomfortable with being milked on a per-quarter basis. In the previous milking system, all four udder quarters were milked for the same duration of time.
Although unlikely, it is possible that the cows took longer than 32 days to adapt to this change.
The number of incidents of elimination and vocalization were great during the first 24 hours of use of the robot system ( Figure 3 ).
However, subsequently these events were low to nil.
Importantly, milk yield, which had dropped to an average of 35 lbs/cow in their first 24 hours in the new barn, rebounded to nearly 70 lbs/cow/day within four days ( Figure 4 ).
Reduced milk yield in that first day was most likely because the cows were not fully letting down, particularly during their first milking by the robots.
During the first milking, the robot uses lasers to scan the udder and teats to learn the cow’s conformation.
This process can take several minutes, which caused the first robotic milking to be longer than all later milkings; a fact which may have contributed to the cow’s discomfort during her first milking by the robot.
Another indication that cows adapted quickly to the robotic milkers was the number of cows that milked themselves voluntarily versus the number that needed to be fetched by the stockperson to be milked.
Within a week of introducing the cows to the robotic milkers, over 80 percent of the herd was milking voluntarily.
After two weeks, over 90 percent of the herd was milking voluntarily and after two months over 97 percent of the herd was milking voluntarily.
Only two to three cows needed to be fetched every 12 hours to be milked while the remainder of the herd went through the robotic milkers voluntarily over 2.5 times per day.
In summary, according to most of our measures, the cows seem to have adapted quickly to being milked by the robotic milkers. One puzzling piece was the increase in the number of steps and kicks following teat attachment.
Unfortunately, this result seems to have left us with more questions than answers, and it may be worthwhile to further investigate the rate of adoption between these two systems.
Extending the data collection period beyond 32 days also may be necessary during future investigations, as it may take longer for cows to adjust to milking with a new machine than previously thought.
The PDREC farm staff worked closely with Lely representatives to design a transition protocol based on the manufacturer’s previous experience and our particular herd and facility.
If you are considering a transition to robotic milkers, we recommend taking advantage of the manufacturer’s advice. You also should invest some time talking to other producers who have made the transition to learn about possible problems and solutions. PD
—Excerpts from Michigan Dairy Review, Vol. 15, No. 4, pages 8-11.
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