Here you'll find comprehensive details of the major trials that NDDT and NARF have undertaken over the last twenty years.

Please email us via this website for ideas for further research. We welcome all comments.

See below for details of

- Imported Feed Trial

- Partner Farm Project

- Kikuyu Trial

- Gibberellic Trial

- Mastitis Trial

- Split Calving Trial


For copies of papers presented at field days and conferences click here



Northland farmers have clearly identified that they would like to reduce their reliance on imported feed, and need to know the financial implications of this.

This 3 year trial finished in June 2018 and addresses the following issues:

  • Can Northland dairy farms maintain production and profit with reduced imported feed
  • How do we replace imported feed with extra forage grown on farm
  • How do we manage climate variation with reduced reliance on imported feed

There are three farmlets of 28ha each capturing physical and financial information about the farming systems:

PKE Farmlet 20 – 30% of feed imported, primarily as PKE.

Cropping Farmlet All feed grown on farm including a range of forage crops such as maize, turnips, fodder beet.

Grass only Farmlet Baseline production and profit to evaluate the impact of supplement use and cropping within farmlets 1 & 2. No imported feed or cropping.

See below for the full summary of results for the whole three year period, showing the profitability of the Pasture Only Farm and the PKE Farm surprisingly close, with the Cropping Farm the least profitable in all three years

For more detailed information on any of the three years contact info@nddt.nz


The Northland Partner Farm Project followed on from the success of the Northland Focus Farm. Two further farms were monitored and mentored through three years to make significant improvements in their businesses. Click below for full details


This trial at NARF compared a kikuyu based farmlet with a ryegrass farmlet for profitability under best practice. The kikuyu was mulched and undersown with Italian rye in autumn, effectively transitioning the pasture to ryegrass each spring. Supplements were fed in order to maximise profit on both farmlets. Over a three year period and with a range of climatic conditions the trial showed that well-managed kikuyu can give similar profit per hectare as rye-based pastures.

This would suggest that efforts should be focussed on managing kikuyu well rather than eradicating large areas of kikuyu. Download the 2 page summary or the full report below


Download the farmer guide to managing kikuyu. This general guide has been developed by NDDT and DairyNZ. Farmers should note that optimal management techniques may vary between farms.


Up to three applications of Gibberellic Acid (Gibb) on ryegrass plots in July to September gave good immediate pasture responses of 400 - 600 kgDM/ha. However most of this additional pasture was lost afterwards due to "post-Gibb depression." Repeat applications of Gibb delayed this depression in pasture growth.

This is consistent with other trial work, showing that Gibb is a useful tool for bringing pasture growth forward in early spring but does not increase overall DM production, and there can be a significant reduction in pasture growth following the last application.


There have been many studies looking at the effects of teat spraying (TS) and dry cow therapy (DCT) as single treatments.

This trial was unique in the way it measured how a combination of teat-spraying and whole herd DCT affect clinical mastitis and production in a pasture-based herd.

TS lowered the number of mastitis infections but there was no effect on production of either TS or DCT over the two seasons.


This 3 year trial at NARF compared all autumn calving with spring calving. The farm has very wet soils and was a real test for winter milking, but the trial showed that a high level of pasture management was more critical to the success of winter milking than soil type.

The autumn calving cows had longer lactations and higher production per cow than spring calvers but the lower stocking rate caused slightly lower production per ha.

Profitability of the autumn calving farm was driven by the size of the winter milk premium and the cost of imported supplements.

The results showed the premium for May to July at the time needed to be 90 cents/kg milksolids for autumn calving to be as profitable as spring calving, and the Northland Dairy Company used this information to set their winter milk contracts.


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