|
|
|
Ju
ne, 1999ROTARY PARLORS
An Update
In the August, 1998, issue of this newsletter, I discussed the shortcomings of rotary milking parlors. Specific concerns centered on cows entering and exiting the platform, available machine-on time and the pre-milking udder preparation routine. Each of these concerns relates to the rotation rate of the platform.
A full pre-milking hygiene routine is generally preferred because of its potential benefits to udder health, milk quality and milk flow rate. But a full pre-milking udder preparation routine will suffer in a rotary parlor because of the natural tendency of the operator to attach the milking machine to the cow soon after she enters. In fact, since current rates of rotation are often less than 15 seconds per stall, a single operator cannot both prepare the udder and attach the milking machine. This adds extra people.
Rotary parlor throughputs are often based on the rotation rate per stall; e.g., 15 seconds per stall yields a theoretical throughput of 240 cows per hour. Unfortunately, platform rotation is often interrupted because of balking cows at the entrance, milking not being completed as cows arrive at the exit, operators falling behind in their work routine due to machines dropping off or other malfunctions, etc. Rotating the platform at a faster rate (which reduces the time per stall) gives greater theoretical throughput but accentuates all of the above problems. Plus, rotating the platform at a faster rate requires that more stalls be on the platform in providing the same available milking time.
Data presented recently by John Smith (KS), Dennis Armstrong (AZ) and others have confirmed all of these shortcomings. From time studies on 14 rotary parlors on commercial dairies, they found that actual throughput averaged about 80% of the calculated theoretical throughput. Average labor efficiency was 112 cows per person-hr. However, the pre-milking udder preparation routine in the majority of parlors was minimal (including only strip and/or wipe) or no udder preparation (machine attachment only). Furthermore, milk production averaged only 64 lbs milk per cow per day. Thus, rotary parlors, costing more than conventional parlors, offer no particular advantage with respect to labor use.
High-producing cows and a full pre-milking udder preparation routine both increase the number of stalls on the platform. Smith, et al., recommend that the parlor be large enough to allow at least nine minutes of available machine on time. Thus, a platform with 56-60 stalls would be required to provide this, assuming 5 stalls for entry and exit, 3 stalls for pre-milking hygiene and 2 stalls to detach machines.