Over the past decade many of these people have remained in New Zealand and become highly valuable employees for our dairy farmers.
The dairy sector thinks its employees from overseas should be treated on a par with other industries which employ staff from overseas, such as hospitality.
When a hospitality employee is paid $19.97 per hour they escape the cycle of uncertainty brought about by yearly reviews, they can bring their family to New Zealand, and they can remain here for more than three years. For the sake of equality, shouldn't this also apply to farm employees?
Instead, the latest changes introduce wage levels for many farm staff which mean that unless they are on more than $35.24 per hour they are classified as "low-skilled" because visa requirements are based on both wage rates and Immigration's classification system.
This system currently recognises farm employees as either entry-level or expert when in fact many fall in between. The system recognises the full range of skills in other sectors.
New Zealand is already losing - and will now continue to lose - well trained migrant farm employees to other countries where visa requirements are not as restrictive and where overseas farmers recognise the value of Kiwi-trained and experienced staff.
Like any other sector, dairy is committed to providing a fair wage and positive work environment. Dairy isn't unusual in the fact that its employees experience fluctuating work hours during peak times such as the calving season, just as I imagine politicians and their staff do during election season.
However, we are working with farmers towards a 50-hour work week as part of dairy's workplace action plan. We're very aware that it isn't just up to the Government or regional economic development agencies to entice Kiwis into the regions where these jobs are, and we want to ensure working conditions are attractive to all good quality candidates.
The number of suitably skilled people from overseas working on New Zealand farms cannot be reduced until there is an ample, and ongoing supply of suitably skilled Kiwis to fill those roles. One way to get there is through dairy's partnership with the Ministry for Social Development to train Kiwis to be work ready and farm ready.
This is a long term endeavour, and the number of people coming out of the programme is just not enough to fill current vacancies, never mind meet future demand.
Many of the people from overseas are longstanding, valuable members of our rural communities and they are the ones, with the on-farm experience they have built up, who will be training Kiwis who want to enter the farming workforce.
This is about ensuring that dairy can employ, and retain, the staff needed to safeguard the sector's vital contribution to the New Zealand economy - upwards of $12 billion. Little of this remains in the farmer's pocket.
Much of what dairy farmers earn is spent running their businesses as they purchase goods and services from the range of companies supporting the agricultural sector.
Not only does this expenditure by farmers benefit these companies directly, but there is also the roll-on effect, and the taxes farmers pay, that significantly contributes towards the standard of living, the infrastructure, the goods and services, appreciated by everyone living in this country.
• Dr Tim Mackle is chief executive of DairyNZ which represents dairy farmers with the purpose of securing and enhancing the profitability, sustainability, and competitiveness of New Zealand dairy farming. For more information, visit www.dairynz.co.nz