DairyNZ researchers have taken a look at how an extended lactation system could deliver farmers a more flexible, worker-friendly farm environment, without sacrificing profitability in the process.
DairyNZ scientist Lydia Farrell presented a paper at the 2023 Grasslands conference, co- authored by colleagues Kirsty Verhoek and Dr Paul Edwards. They modelled the impact of an 18-month and 24-month extended lactation programme across four dairy areas – Northland, Waikato, Canterbury and Southland.
The motivation for the study came from DairyNZ’s work with a farmer co-design group, working to identify what farmers’ key concerns are in their dairy farm business operations.
One of these is the availability of labour, the demands placed upon labour, and the flexibility that can be built into dairying jobs to make them more appealing to staff.
“In terms of industry statistics, our labour productivity has also plateaued at about 150 cows per labour unit. A system that could flatten the peaks both across and within a season may unlock a step change in efficiency,” Edwards says.
Globally, extended lactation is nothing new. But it proves to offer challenges when it is incorporated into New Zealand’s predominately pasture-based dairy system, with the inherent seasonal peaks and troughs in feed supply.
The modelling predicted the “EL24” (24-month extended lactation, with half the herd calving each year to flatten the seasonal peak in workload) system likely would deliver the best outcome for farmers in Northland. It was shown to improve net income against spring calving with typical 12-month intervals by $439 a hectare, an amount the researchers said exceeded their initial expectations.
The other three regions experienced negligible or negative net gains of -$31/ha in Waikato, -$151/ha in Canterbury and -$131/ha in Southland, compared to the base system.
Overall, the EL24 system proved to deliver lower losses or, in the case of Northland, higher gains than the 18-month (EL18, also with offset herds) alternative.
“With the 18-month system, your ‘dry’ period will move around. Every year will be different, demanding a different approach to how you manage it, and the modelling suggests supplement use will be greater,” Edwards says.
Northland’s positive outcome with EL24 was driven by lower supplement costs, thanks to a smaller variation between peak and trough pasture growth. As expected, the zero- to low-pasture growth days over winter in the South Island resulted in greater supplement input and associated costs, lowering net returns.
Edwards has emphasised the study was based only on modelled systems, but it has highlighted not only the potential to run such a system profitably, but also the many “unders and overs” investigating such a system uncovers.
“We did not look at in calf rates as an outcome of the systems. But logically that may be another advantage –from an animal health perspective you are reducing that pressure you get every season by mating them at day 400-450, rather than at peak lactation.”
There is also an impact on herd demographics and replacement rates that needs to be better understood.
“Because of the 24-month calving interval, the average age is older, and there is an opportunity to reduce replacement rates,” Edwards says.
Should farmlet-scale testing support the modelling, he’d also be interested in better understanding the genetics most suitable for herds that calve under an EL system.
“There is probably a lot of variation in cows suitable to it, so there it is also logical you will be able to select for that.”
For an area like Northland, which has experienced considerable moves out of dairy into beef in recent years, the trials results may also provide grounds for considering sticking to dairy.
“Looking at it as being similar to once-a-day options, it is going to tick boxes for reducing that amount of seasonal work. But if your reason for considering it is due to ageing infrastructure, it’s unlikely to help.”
The paper has given the researchers confidence to investigate further, setting up a trial on Scott Farm at DairyNZ with base herd of 42 cows calving every 12 months compared to an 84-head herd on EL24.
Having started on June 1 last year, it should run for at least two years. The results can be followed in the Frontier Farms section of DairyNZ’s website.
This article first appeared in our sister publication, Dairy Farmer.
