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- How do I manage my pasture when automatic milking?
To achieve a >70% utilisation rate with approximately 80-90 cows per milking station, without extended cow waiting times, requires good control of cow traffic. This is achieved using drafting units or selection gates, positioned either in the dairy or along the raceways remote from the dairy, which automatically allow targeted cows to enter a new grazing area, be returned to older pasture or sent to the dairy for milking. Typically two or three new areas of pasture are available to the herd daily, with one of these occurring near midnight to ensure the milking stations are kept busy during the early morning hours.
- Do I need to change my grazing system?
The simple answer is no!
Profitable operation of pastoral dairy systems is based on the correct feed allowance per cow that will result in optimal/profitable feed conversion efficiency per cow and hectare. Research indicates this is in the vicinity of 80 – 90kg LWT/t DM.
Grazing systems have been developed to utilise pasture efficiently and allocate feed to the herd in a manner that balances cow production and profit. There are grazing ‘tools’ in use that enhance this (e.g. pre-graze mowing, returning cows to a grazed area until the desired residual is achieved), and pastoral AMS utilises many of the same ‘tools’ but with a few extras.
- But you will need to change the grazing method.
Within a batch milked system control over access to grazing (duration, area, mass, herd size), and milking frequency (herd scale twice a day, once a day (or combinations within the herd) are directly imposed in the day-to-day operation of the farm.
By contrast automatic milking relies on voluntary cow movement from the grazing area to the AMS. Control of the operational running of the farm is then a shared function between farm staff and the cows themselves. It is important that rotational grazing is balanced to induce cow movement. To achieve this at least two and preferably three allocations of fresh pasture (or other feed) are offered each day.
- How does it work for all pasture systems?
Many people believe that all grass dairy systems cannot work with voluntary milking. DairyNZ research has shown that with appropriate cow traffic systems in place 24h milking can be achieved with just 2.5% of the diet concentrate fed through the AMS and over 13 T/ha DM can be harvested from the farm.
Feed availability is a prime motivator of cow movement, in particular pasture residual mass is a critical factor that motivates the cows to move. Voluntary cow movement is necessary to obtain a desired milking frequency, which affects milk yield. The effect is a cyclic pattern of linked events that will determine productivity of the system. (Figure 1 below.)
Figure 1. Cyclic pattern of pasture harvested, milking frequency, and milk yield within an AMS.
As pasture residual levels increase the cows will reduce voluntary movement and therefore milk less frequently with the flow on affect in reduced yield. This creates a reduced feed demand, which in turn will result in higher residual mass level. The direction of this cycle is critical for pastoral AMS.
- What if the feed balance changes?
A flexible approach to manual cow movement has a positive affect especially during periods when pasture supply exceeds demand. Typically, cows remaining in a grazed area would be manually moved from that break twice daily. Adopting a flexible approach to the timing of these manual moves can allow for greater control over post-grazing residuals and therefore intakes. There are other flow-on benefits in terms of increasing milking frequency and AMS utilisation. The timing of manual moves is determined by cow traffic patterns, paddock location, time of day and grazing residual.
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