The Northland Dairy Development Trust and Northland Agricultural Research Farm is applying science to test management systems in a changing environment. Chris Neill reports.

The New Zealand dairy industry is well served with information from the basic principles to new technology, helping farmers deal with almost every matter in their farming operation.

Much of that information is based on disciplined research with scientific rigour to encourage confidence in the messages delivered, acknowledging that understanding of data leads to challenges of interpretation.

The cost of the science is high, so sharing and implementation of the learning is critical to creating value from the research effort. Because of the cost, research is often carried out at centralised locations, a factor which is then used by some farmers to dismiss the messages as irrelevant to their circumstance. Northland dairy farmers are fortunate to have Northland Dairy Development Trust (NDDT) and the Northland Agricultural Research Farm (NARF) providing information that is regionally and nationally significant. NDDT directs the science and NARF provides the specialised farm facilities plus cows for trials funded by DairyNZ, MPI and Hine Rangi Trust.

A Northland team of dedicated farmers and rural professionals are committed to producing meaningful science and ensuring the ongoing viability of the research farm. The three-year NDDT/NARF project “dairying in a variable climate” is in its final year. Through the first two years climatic extremes of wet and drought have tested the team to maintain protocols and produce uncompromised data. There is a connection between this trial and the previous which allows base data to carry forward and provide greater confidence to recommendations for farmers after the extreme weather conditions experienced to date for this trial.  The clear messages coming from the trial are:

Based on farm input costs, regardless of seasonal conditions the farm milk price needs to be greater than $6/kg milksolids (MS) for input of imported feed to be profitable.

Behind this recommendation, it needs to be recognised that NARF is achieving 100g MS/kg drymatter (DM) supplement fed. This is significantly better than the industry average of 70-80g MS/kg DM fed and suggests the average farm could need a 25% higher milk price to be profitable.

Analysis shows for each $1 spent on supplement there will be additional costs of 60-70c for labour, machinery, and a collection of other minor costs. This is exclusive of wastage which with some palm kernel feeding systems can lose up to 25% of the feed purchased. Minimising supplement wastage is a key factor in the milk response achieved to supplement fed.

Profitability of supplement feeding is more dependent on maintaining pasture residuals than the price of the supplement.

When the need for supplement is identified, a common response is to invest time seeking the best possible purchase price for that feed. Pasture is written off as not able to deliver. However, pasture remains the lowest-cost feed. Optimising its contribution through monitoring residuals ensures the least amount of more expensive supplementary feed is required as well as providing pasture plants with the best chance of regrowing.

Simply – an investment in monitoring pasture residuals gives better return than chasing discounted feed.

When sufficient pasture is available, cows are very adaptable to the addition or removal of supplement from their diet so adjusting the amount of supplement fed to maintain pasture residuals will not compromise milk production.

Adding supplement to cows fully fed on pasture after calving makes negligible improvement to in-calf rate.

There was no increase in reproductive performance in the supplemented herds compared to the herd fully fed on pasture, endorsing the well-established recommendation that cow condition at calving is critical for achieving a high in-calf rate.

Red, green and blue herds

To achieve the system comparisons that deliver these recommendations, NARF operates three independent herds on 28-hectare farmlets within the farm. The farm engages additional staffing, allocates randomised paddock for each herd and collects each herd’s milk in separate vat.  Make-up of the three farmlets:

Pasture-only farm, (2.7 cows/ha). There is no imported feed so pasture allocation and harvesting of any surplus grass are crucial. When weather conditions totally compromise pasture growth and conserved feed is used or allocated, the options are staged through OAD to drying off to culling.

Palm kernel-only farm, (3.1 cows/ha). The only input beyond Pasture Only farm model is imported palm kernel. This is a relatively common system in Northland. There is an absolute focus on optimising pasture utilisation through managing residuals and adding palm kernel only when required. Keeping the milk within FEI limits is another constraint and having milk collected separately provides a clear view of this factor. Fonterra monitor inputs and outcomes to assist the company in understanding the FEI interactions.

Palm kernel-plus Farm, (3.1 cows/ha) imports palm kernel and other supplements to fill pasture deficits when pasture residuals indicate the need for additional feeds. This allows for fully feeding cows at all times and adjusting the rations to avoid FEI issues. Dried distillers grain and imported baleage are the key imports after palm kernel. The farm maintains a staff “worry score” to keep track of the pressure each system puts on staff about feed supply and cow condition. Not surprisingly, through the drought, the palm kernel-plus farm has the lowest “worry score” followed by the palm kernel-only farm – until FEI becomes an issue, and pasture only has the highest average score.

In previous favourable seasons the Pasture Only farm has had a lower worry score as there are fewer decisions to make. The inclusion of financial considerations to the worry score may cause the scoring to be different.

This trial project will conclude on June 1, 2021.

Climate change future focus

Preparations are already underway for the next trial. It will build on the work of the two previous trials to focus on future farming strategies to prepare for coming challenges associated with climate change and understand the economics of these strategies.

It will again use three farmlets with the control, Farmlet 1 being the pasture of rye and kikuyu supported with nitrogen application and palm kernel.

Farmlet 2 will adapt to warming climate by using different pasture species. A combination of fescue, cocksfoot, chicory, plantain and clover will replace rye and kikuyu – the first year of planting has already been done with outstanding pasture production. This farm will have similar stocking rate and input rules to the Control farmlet. Palm kernel will be added as a supplement when pasture residuals fall below target. As a bonus, the separate vats will allow Fonterra to understand the change to milk composition from these alternative pastures.

Farmlet 3 will set out to mitigate the emission outputs by adjusting feeding/management systems to achieve the 2050 emissions targets of 30% reduction in methane emissions and 50% reduction in nitrous oxide. The means for adjusting these emissions will be lower stocking rate, low or no nitrogen application and low or no imported supplement.

The current trial has shown the all-grass farm can achieve 10-15% reduction in methane emissions against the palm kernel-only farm with little drop in profit. This will be of some comfort to farmers as this drop is equivalent to the 2030 emissions target.