Automatic milking systems (AMS) use has increased in the dairy industry in the last few years. Seven percent of all Canadian dairy farms were using some type of AMS in 2015 according to Statistics Canada. But like all new systems, there are benefits and challenges.
A research project investigating lameness in AMS farms (funded by the Dairy Research Cluster 2) led by PhD student Meagan King under the supervision of Dr. Trevor DeVries at the University of Guelph, the team found that one of the challenges of AMS herds was the identification of mildly lame cows. Lameness has an impact on the entire herd, and not just at the cow level. In fact, an increased lameness prevalence of the whole herd reduces overall production.
In the study, 41 robotic herds were surveyed and data about management, barn design, and lameness prevalence was collected. Researchers then looked at risk factors for lameness at the herd and cow-level, as well as factors related to productivity, efficiency, and cow behaviour.
They collected data by visiting 26 farms in Ontario and 15 farms in Alberta. Producers in each farm were asked about feeding, manure, and bedding management. Researchers recorded details regarding barn design and stocking density of cows relative to feed bunk space, lying stall availability, and the number of robots on each farm. They also scored a representative sample of cows at each farm for lameness (gait) to get an accurate estimate of their lameness prevalence, on a scale of 1 to 5 (1 being sound to 5 being extremely lame).
Increased prevalence of severe lameness is related to reduced milk production per cow and per robot. The researchers found that on average, less than 2% of the cows gait-scored were classified as severely lame (gait score of ≥4 out of 5). However, they found on average 26% of the cows gait-scored were moderately to severely lame (gait score of ≥3 out of 5). The majority of the lame cows they observed had a gait score of 3 out of 5.
In the AMS environments studied, cows with a slight, but noticeable limp, are fetched 2.2 times more, milked 0.3 times less per day, and produce 1.6 kg/day less milk than sound cows. The research also suggests that producers are doing a good job of identifying and treating severe lameness cases in their herd. But, the team found that producers have a harder time identifying the mild to moderate cases of lameness (which are labelled to ‘monitor’ under the proAction animal care assessment program).
Manure management had a significant impact on lameness prevalence on farms: herds that scraped manure from walking alleys more frequently had a lower prevalence of moderate lameness and lower rates of fetching cows. Cleaner floors improve the mobility of cows, which is important when those cows walk to a robot to be milked then back to their stalls or feeding area.
Stocking density affected production and lameness on farms: greater stocking density in lying stalls was related to higher severe lameness prevalence, and led to producers having to fetch more cows. Although a higher stocking density at the robot was associated with increased production per robot, it also reduced milking frequency per cow.
Cows with low body condition and cows of higher parity were more likely to be lame. This is consistent with other research: thin cows also have a thin digital cushion in their hooves, predisposing them to mechanical causes of lameness (i.e. sole ulcers).
These findings suggest that producers should manage, monitor and treat lameness early to improve animal care and prevent loss of production in AMS environments, similarly to other barn and stall types. Some ways to achieve this is to get trained to gait score cows and identify those mild cases of lameness and take corrective action. Producers should also be aware of cows’ body condition as thinner cows may have more underlying problems that should be investigated.
Producers with AMS should aim to keep floors clean to give cows an appropriate surface to walk on to and from the robot, as well as giving cows enough clean, comfortable, well-bedded resting space to maximize animal comfort, production potential and prevent lameness.
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Meagan King is a PhD candidate in the Department of Animal Biosciences at the University of Guelph. Emilie Belage is an MSc graduate from the Department of Population Medicine at the University of Guelph and veterinary medicine student at Michigan State University.