In some cases the decision to go for a rotary platform is made easier on grounds of scale, but in others it can be a decision influenced by the considerable difference in capital cost between herringbone and rotary. It can also come down to more than just money when deciding which option is best.
Don Chapman of Morrinsville has spent decades building farm dairies, and said farmers planning to upgrade or purchase a farm milking between 350 and 600 cows faced the toughest choice on what sort of dairy they should build.
“More than 500, you will probably head to a rotary, and less than 300 to a herringbone. For some, which way to go will come down to payout in that particular year, with the rotary option the choice on a good year.”
He lamented that building a key piece of capital should be determined by payout, and also urged farmers to think further ahead about their investment decision.
“We have found the time involved in getting consents and permits is taking longer than ever. You really need to allow two months after signing a contract just to get the required paperwork through.”
He estimated 70% of the work run through his now-franchised operation would be on rotary dairies.
However the lure of opting for a herringbone on price grounds alone could appear strong, even on larger operations.
Waikato Milking Systems North Island sales manager Paul McGill said a typical cost comparison for a farm milking 600 cows would be about $850,000 for a 40-bail herringbone, against $1.2-$1.5 million for a 60-bail rotary platform.
“You are saving yourself a lot of money on the capital outlay, but you do have to look at milking efficiencies too.”
Milking 600 cows through the 60-bail rotary would take 1.5 hours based on 10 eight-minute rotations, compared with 15 rows through the herringbone taking 2-2.5 hours a milking.
There was also the ability to highly automate the rotary platform, requiring only one operator against needing two in the herringbone.
Typically the labour economics of a herringbone also get thinned once the dairy goes to more than 40 bails, where a third pair of hands is inevitably required.
‘You are saving yourself a lot of money on the capital outlay, but you do have to look at milking efficiencies too.’
Chapman said having fewer staff had wider implications. It could reduce the need for staff housing, meaning an additional $300,000 wasn’t needed. But a technologically advanced rotary also bought the need for a more highly skilled, capable operator.
GEA Farm Technologies national capital sales manager Adam Franklin said the “batch” milking of cows in a herringbone also became more problematic at a milk quality level as numbers crept up.
“With a rotary you have a more constant milk flow, with cups constantly coming off and going on. The higher surge of milk with a herringbone puts more pressure on plate heat exchangers , and will become more so with increased milk cooling standards.”
But he said whatever option was chosen, the simplest question was the one that needed to be asked first.
“That is to ask yourself, ‘is this the most cows this farm will ever milk?’”
Future-proofing the operation started with scale and might involve building a dairy that was “comfortable” for a few years.
For example, building an overspec’ed 60-bail rotary for 400 cows was better until the neighbour’s farm was purchased a couple of years on when 600 cows would be milked, rather than trying to expand shed capacity later.
Franklin had seen some recent quotes for “double pit 20” herringbone designs with a low-line plant installation and a rapid exit system.
“But you are starting to get in costs similar to rotaries with those.”
Next to future farm size, technology should also be considered before choosing design.
All dairy and plant manufacturers agree technology is easier to install and upgrad in rotary platforms.
Installing systems like feed-to-yield in herringbones can be difficult and more expensive, with every individual feed head needing individual inputs and sensors, and still fraught with accuracy issues if cows pushed ahead while rowing up.
Franklin said as the industry tried to maximise per-cow production and reduce its nutrient footprint, the technology for individual performance monitoring was going to become more critical, and also help with attracting staff.
