FROM THE FARM REPORT: ENHANCING ROTARY PARLOR EFFICIENCY

As many dairy herds continue to increase the number of cows that are milked and housed in existing facilities, parlor efficiency becomes crucial.

Common metrics include:

• cows milked per hour,

• cows milked per operator per hour,

• and pounds or liters of milk harvested per hour.

For a rotary parlor, efficiency is influenced mainly by parlor size (i.e. stalls), rotation time, and milking duration. To shed some light on other factors influencing rotary parlor efficiency, Cornell researchers conducted a case control study focused on stall unoccupancy and published their findings recently in the Journal of Dairy Science. The study was conducted on a 5,000-Holstein cow dairy where cows were milked 3 times per day in a 100-stall rotary parlor. The parlor rotated at a speed of 4.8 seconds per stall, with milking done by 4 milking technicians at specific stalls: 3 (clean teats), 5 (strip and disinfect teats), 11 (wipe teats), and 15 (attach milking unit). Teat spray robots were located at stalls 92 to 95.

Understanding Stall Unoccupancy

Stall unoccupancy occurs when a stall in the parlor remains unoccupied during a rotation. This can result with disrupted cow flow and reduces the efficiency of the milking process. A stall unoccupancy event was defined as a cow being preceded by an empty stall during milking. A case of recurrent stall unoccupancy (RSU) was defined as a cow experiencing 11 or more stall unoccupancy events during 30 milkings over a 10-day period. The researchers suggested that this metric that might be beneficial for other herds to monitor but indicated that the threshold of 11 or more stalls unoccupied during 30 milking (≥36.7% of milkings) was arbitrary and the biological and economical relevance of that threshold need to be evaluated further.

Key Findings – Risk for RSU

There were 10% of stalls empty per rotation which may have resulted from the higher rotational speed of the platform. A total of 124 cows out of 4,486 cows experienced RSU.

Cow Characteristics: Cows in their 1st and 2nd lactations were less likely to experience RSU compared to those in their 3rd or greater lactations with an odds ratio of 0.06, 0.35, and 1, respectively. This is likely due to the social hierarchy, where older cows tend to be more dominant and create larger “personal space” or clearance zones that may disrupt flow into the parlor. Early-lactation (<100 days in milk; DIM) cows has lower odds (0.56) of RSU than late-lactation cows (≥200 DIM). Mid-lactation cows also had lower odds (0.84) although not as pronounced. Cows that are earlier DIM are generally more motivated to be milked due to higher milk yields.

Health-Related Factors: Cows with a higher somatic cell count (SCC) in milk had an increased odds of RSU; a one-unit increase in log-transformed SCC resulted in a 1.37 odds ratio for RSU. Higher SCC is indicative of mastitis, which can cause inflammation in the udder and discomfort during milking which may cause cows to delay entry into the parlor. Also, cows diagnosed with lameness 1 week before, during, or 1 week after the 10-day period had a higher odds (1.81) of RSU. Lameness can cause discomfort and a reluctance to move at normal pace thereby disrupting the flow into the parlor.

Practical Implications

These findings highlight the importance of monitoring cows’ characteristics and health events to improve parlor efficiency. Here are a few actionable steps:

• Use the RSU definition or modify it to your situation to identify cows that frequently cause stall unoccupancy. Those cows may need assisted entry into the parlor or a career change.

• Find the sweet spot. Optimize parlor rotation speed to minimize stall unoccupancy while maintaining overall parlor efficiency.

• Implement effective treatment and prevent strategies for lameness as well as mastitis to enhance cow traffic into and out of the parlor to promote parlor efficiency.

— Heather Dann

dann@whminer.com