[This post was first published in the New Zealand Sunday Star Times on 2 February 2014]
The New Zealand dairy industry has always prided itself as being different. Whereas most other countries developed their dairy industries based on the housing of cows for much or all of the year, the New Zealand industry has always been pasture-based. The cows harvest the grass themselves, the cost of production has been low, and the image was of ‘clean and green’.
Alas, we now know the image of ‘clean and green’ was never quite true. Although a huge amount has been done to clean up the industry, with fencing of waterways, nutrient budgets and meticulous management of effluent from the milking shed, there is a fundamental problem still to be tackled. This fundamental problem is the concentration of nitrogen in the urine patches which grazing cows leave behind.
The dominant belief amongst scientists is that when a cow urinates she deposits nitrogen in the urine patch at up to 1000 kg per ha. Not all of my animal scientist colleagues are convinced about this specific number, but regardless of the exact amount, it is inevitable that there will be significant nitrogen leaching from urine patches deposited in autumn and winter.
It does not matter what is done in terms of reduced stocking rate or reduced fertiliser or different grasses. As long as the cows are grazing the paddocks in autumn and winter, then there is going to be significant loss of nitrogen into waterways and underground aquifers.
There are four possible strategies.
The first option is to do nothing. That would mean that the leaching problem would get even worse. But that is not an option because New Zealand society is not going to allow it.
The second option is to allow no further expansion of the dairy industry. That too is not an option because even with no further industry growth there will be further build-up of nitrogen in the waterways and aquifers.
The third option is to force a major reduction in the dairy industry. That too is somewhat impractical, given that dairy exports – which in the current dairy season will be more than $15 billion – underpin our New Zealand economy. Without dairy, we would be in enormous difficulty as a nation.
The fourth option, and it is the only one that makes sense, is to get the cows off pasture from early April until the start of September.
Off-paddock wintering systems can be either stand-off (non-roofed) pads or partly enclosed sheds. But stand-off pads bring their own problems. There needs to be collection of all effluent, and without a roof over the pad, the effluent pond needs to be at least double the size it would otherwise be. So in most cases, it means that there have to be roofed sheds.
The appropriate technologies are well understood in both Europe and the United States. Many European countries legislated some decades ago to ensure that cows were held inside during winter, and that the effluent could only be taken back to the paddocks once the soils were drying-out in spring. We now have to adopt and adapt these same systems to work in the New Zealand environment.
Of course there are substantial capital costs associated with these shed-based systems. For a shed that is suitable just for wintering dry cows, then the overall additional capital requirement will be about $2000 per cow. For a system set up to include milking cows, then the cost will be even higher as the cows need to be kept cleaner.
In very broad terms, the total capital involved in a typical New Zealand dairy farming system now exceeds $60,000 per hectare. On a per cow basis, this is typically between $15,000 and something over $20,000 per cow. So the additional capital of a shed is significant. Also, this shed capital, unlike land, depreciates over time, and so it can add significantly to the cost of production.
Accordingly, it is not surprising that many dairy farmers are strongly opposed to the idea of having to house their cows. Nevertheless, there are now several hundred farms in New Zealand that already house the cows in winter. We are also starting to see farms, as in the United States, where the cows are housed throughout all of the year.
There are actually multiple benefits that can be achieved by housing of cows. In winter, the animals need less energy to maintain their body temperature, and in summer there is no heat stress in a well-designed system. Cows no longer use energy trudging several kilometres each day to and from the dairy shed. This walking can also be a major source of lameness. Fonterra has found with its China-based farms that when New Zealand bred cows are shifted to an enclosed system, the total milk production per lactation from each cow more than doubles.
When everything is done correctly, housed cow systems are still compatible with a low cost of production per unit of output and a high return on capital. Indeed the 2013 winner of the New Zealand Dairy Business of the Year – for which I was one of the judges – was for a farm that housed the cows in winter. The key judging criteria were overall return on capital and environmental sustainability. So it can be done.
Nevertheless, this idea of housing cows in winter is going to be highly controversial. Many farmers will resist the idea fiercely. The general public will also need to get used to the idea of cows being housed. Society will need to be convinced that animal welfare is being dealt with appropriately. In that regard, we can learn a lot from the Europeans.
In the long run, getting cows off the paddocks in the autumn and winter is the only way for New Zealand to go. It is the only way we can maintain both an image and a reality of ‘clean and green’. But it is going to be an interesting and very controversial journey. It goes against much that we have believed in for a very long time.