Rise of the rotary – but is it a runner?

There has been a steady increase in the number of new rotary milking parlours being built in Ireland over the last few years. While the proportion of rotaries being built relative to herringbones is still low, the trend is definitely towards more rotary parlours, particularly on large farms.

So what are the deciding factors? Obviously, herd size is important. Rotary parlours are more efficient but are also more expensive to build, so there is a critical herd size needed to justify the extra expenditure.

Small rotary parlours of 20 to 30 bails were common in the past, but are no longer seen as efficient. When we talk about efficiency in milking parlours, the best measure is the number of clusters attached per man per hour.

The problem with smaller rotaries is that because it takes between six and 10 minutes for a cow to milk out, the platform needs to be moving slowly to have 80% to 90% of the cows fully milked before it does a full turn. This means that the milker has increased idle time between putting on clusters.

The general consensus in the industry is that 40 is the minimum number of bails for a rotary parlour to be efficient.

Advantages

The big advantage of a rotary over a herringbone is undoubtedly labour efficiency and improved comfort for the milker, leading to a better milking environment. In terms of output, the expectation is that medium-sized rotary parlours of 40 to 50 bails should allow for one man to milk between 250 and 350 cows per hour.

Of course, this level of efficiency is dependent on cow flow and automation. For a one-man rotary parlour, automatic cluster removers are a necessity. The alternative is to have someone taking off the clusters before the cows come off the platform, which is non-runner for most farmers.

Another piece of technology that many farmers install on rotaries are automatic retention bars. These prevent cows that are not fully milked from coming off the platform, thereby keeping them on for another turn. If the clusters are still attached when a slow milking cow reaches the exit point, the retention bar automatically drops down and keeps the cow in place.

The alternative to automatic retention is to identify the slow milkers and to tie a chain on to the back of the bail to keep her from exiting after the first turn. The milker then removes the chain as she passes for the second time. Automatic retention costs in the region of €1,100 plus VAT per milking unit, so some farmers will decide to install these at a later date and will use chains for the first few years to reduce capital expenditure.

Automatic teat spraying is another piece of kit common on rotary parlours. Because in a one-man rotary the milker is not present when the clusters come off, some form of automatic teat-spraying is necessary, if post-milking teat-spraying is to be practised. Cows can either be sprayed when on the platform as the clusters are removed or externally as they walk through a drafting gate.

Cow flow

While good cow flow is essential for efficient throughput in any type of milking parlour, it is even more necessary in a rotary as the milker cannot leave their spot without stopping the platform. For this reason, many rotary milking parlours have backing gates installed and have the yard designed in such a way so that the cows will return to the field immediately after milking. That way, there is no backlog of cows at the platform exit.

Costs

The difference in cost between a herringbone and a rotary parlour is not easy to quantify. Like with everything, you need to be comparing like with like when looking at prices and this is not easy when it comes to milking parlours. It all depends on the level of technology employed on each parlour and the size. Broadly speaking, rotary parlours are more expensive to construct, but the differential in price is much less than many people presume.

The following is an example of the type of costs I have seen for milking parlours for large herds built on greenfield sites in Ireland over the past 12 months. These are total costs net of VAT, so include concrete, builder, steelwork, wiring, plumbing, collecting yard, automatic drafting, backing gate, in-parlour feeding, auto-washing, ACRs, bulk tank and the actual milking machine itself.

Of course, there can be a huge variation in the spec used in building a parlour but in these examples each parlour was a basic New Zealand style without any extra frills, i.e. the collecting yards were uncovered and the sides of the herringbone parlours were left open. That said, some farmers are much better skilled at project management than others and can get projects built for a fraction of the money some people spend. The costs outlined do not include soiled water storage.

It should also be said that there are more options available to dramatically cut costs when building a herringbone, eg secondhand but other than not roofing it, it is much harder to do this with a rotary.

Labour availability is a key consideration when choosing a rotary over a herringbone. With a rotary, one person can milk over 400 cows on their own whereas in a herringbone of more than 30 units, it is nearly always a two-man job.

This means that over most of the year, two full-time people can run a farm with a rotary parlour (including holidays/weekends), while three full-time people would be required to run a farm with a 30-unit plus herringbone parlour to provide the same level of cover. In many cases, the extra capital cost of the rotary will be paid back by having less labour on the farm.

The other big issue is land availability around the parlour. Farmers who rely heavily on rented land, which is not tied down in a long-term lease, may be reluctant to spend the extra money on a rotary when their land base is not secure. One of the downsides of rotary parlours is the fact that they are impossible to expand unlike a herringbone parlour, which can be extended either to the front or back. This means that the rotary needs to be appropriately sized from day one, taking into account future expansion of the herd.

Edmond, Jim and John Power are milking 360 cows near Callan in Co Kilkenny. A new 50-bail Dairymaster rotary was installed in August 2014. Edmond explains why they went for a rotary: “We were milking in a 14-unit parlour but, as the herd started to grow, it was taking too long to milk. We are milking 360 cows this year with plans to grow the herd more over the next few years because we have the land available to us.

“The rotary is a pleasure to milk in. There’s usually two of us around the parlour, because it works smoother with two, but on Sunday evenings usually only one of us does the milking – we just slow down the platform a bit.”

The Powers’ rotary has cluster removers, a dump-line and automatic teat spraying. They opted against automatic retention, but this is something they are considering installing in the future.

“Depending on the time of year, there are usually one or two cows out of 50 that need to go around a second time. It’s not a big deal but if I was on my own more, then I’d probably have auto retention,” Edmond says.

The total cost of the parlour, including bulk tank, building works, shed and backing gate was around €10,000 per unit.