When deciding on dairy type it is important to start by defining what you require from your farm dairy, and then select the dairy which best suits your needs. In 2013 72% of dairies in New Zealand were herringbone and 27% rotary. The size of the dairy should be considered at the same time as selecting a dairy type.

• Sizing the dairy

  As the life of a dairy is at least 25 years, when building a new dairy it is important to give a lot of consideration to the size, particularly with rotaries as they do not lend themselves to expansion.

  When considering the optimum number of clusters the following should be taken into account:

  • labour efficiency
  • cow numbers
  • capital cost
  • other factors such as personal preference and the potential for increasing herd size in the future.

  Planning is important to ensure that you get a dairy which suits the needs of your business and the people in it.

• Considerations

  The optimum cluster number in a dairy is dependent on cluster throughput in relation to milker throughput. It needs to be recognised that at the upper limits people are working to a high level of efficiency which they may not be able to maintain. Also that whatever limit is suggested there will be farmers gearing up to exceed it!

• Using labour efficiently

  Although other critical factors include availability of capital, perception on practical milking times and personal preference, a key driver for dairy size should be efficiency of labour utilisation.

  It was once thought that people could only milk about 10 rows of cows in a herringbone without getting tired and also needed to leave enough ‘free’ time to do the rest of the farm work. Now there are dedicated milkers doing little other farm work.

  In this situation it is best that milkers are rostered in shifts so that although the milking time may be extended – thereby making more efficient use of capital - individual milkers are not working for prolonged periods of time. Note that it is still possible and desirable to provide work of varying responsibility and variety to relieve monotony; to help create interest and challenge.

  When considering labour in relation to dairy size, think about the following points not only with present staffing in mind but for the future:

  • How many people will normally milk?
  • Will a number of different people milk during the week?
  • What type of labour is available long-term? Skilled or unskilled? Fulltime or casual?
  • How long should the milking take? Is it important for the milking to be restricted to less than two hours? Can the dairy operate for much longer at each milking shift?

• Automation

  The use of automation can have a large impact on labour efficiency and the sizing of the dairy.

  Automatic cluster removal and automatic teat spraying on a rotary can remove the need for a person at the clusters-off position for much of the lactation period. In herringbones, it removes the risk of over-milking and makes it possible to extend herringbones to about 30 clusters and still be managed by one milker. Automatic teat spraying in herringbones also makes milking easier.

  Automatic drafting is becoming the norm in all large dairies, herringbone or rotary, due to labour savings and stress-reducing attributes.

  Dairy Type	Maximum cluster numbers*
  Herringbone	Without automation	With automation
  1 person	18-22 clusters	up to 30
  2 people	26-44 clusters	up to 50
  Rotary	Without automation	With automation
  1 person	-	50-60
  2 people	50-60	up to 80

• Building in flexibility

  • change in farm size and / or changes in herd numbers;
  • increases in average production/cow;
  • changes in milking frequency, e.g. to once-a-day or 16 hour interval milking
  • availability of skilled labour;
  • changes over time in average size of cows in the herd;
  • changes in the rate of milking, at different stages of the lactation, in seasonally-calving herds;
  • changes to feeding systems in the bail due to automation or increase in quantities;
  • distance to the dairy from the furthest paddocks i.e. walking time for the herd. Two smaller dairies rather than one large could be more effective e.g. on a narrow farm milking 1500 cows, it may be better to consider building 2 one milker, 50 bail rotaries rather than 1 two milker, 80 bail unit where cows need to walk a long way.

  For a more detailed examination of techniques to use when sizing a new farm dairy see the document below “Sizing a dairy to maximise milking efficiency”.

Summary

• Try to be open-minded about dairy type - start with your requirements then choose the dairy to meet these.
• When deciding on a new dairy give yourself time to gather information and advice. Good planning will ensure that you get a dairy which fits all your requirements.
• Seek expert advice. With the range of skills needed in developing a new dairy, advice is needed from several different sources. These include: dairy builders, the local authority, milking machine companies etc. In particular, consider the benefit of specialists in milk harvesting who may have a better understanding of the details of design and their impact on cow flow. Allow plenty of time to analyse, double check and test any advice.