To butcher a metaphor, the baby will not be thrown out with the bathwater. Pasture – grazed the old-fashioned way by hoof and tooth – will make up the majority of the diet for cows involved in the soon-to-be-started systems comparison trial at Massey.
Project co-ordinator Dr Christine Christensen and the research team would not have it any other way.
“We are not housing cows – we are using the barn as a tool to increase productivity and reduce the environmental footprint.”
The barn is built to a standard that means 200 cows can be housed 24 hours a day for 365 days of the year. The plan, however, is to use the barn as part of a stand-off strategy to protect soils in the winter and spring and reduce the paddock urine load in the autumn – the barn will be used part-time only.
The trial builds on earlier smaller-scale work carried out at Massey on controlled duration grazing which measured a 36% reduction in total nitrogen losses relative to a typical system with cows grazing about 20 hours a day. To achieve that, the cows spent eight hours a day paddock grazing and the rest of the day standing off.
The Tokomaru silt loam soils of the 231ha effective No. 4 Dairy are unforgiving. Setting like concrete in the summer, they are notoriously soft and sticky when wet making them particularly susceptible to treading damage in the winter and spring.
The farm is extensively drained by tile, Novaflo and moles, so getting the timing of fertiliser and effluent applications correct is critical.
No. 4 Dairy operates under a spring calving system, with the mixed-age cows kicking off the 10-12 week calving period about August 1. Traditionally, about 40% of the mixed-age herd and the first-calvers, or about half of the 650-cow milking herd, is grazed off for six to nine weeks over winter.
Average annual rainfall sits at about 1000mm with the wettest months historically July and August. This generally coincides with high pasture covers built up over winter going into the first spring grazing round and with an increasing stocking rate as cows return to the milking platform for calving. For soils with poor natural drainage, these factors can create the perfect storm for treading damage if the risks are not carefully managed.
For the last decade or so, No. 4 Dairy has had a 300-cow traditional concrete feedpad beside the 50-bail rotary dairy. Used to feed mostly grass and maize silage, with some inputs of palm kernel, the farm would be classified as a System 3, or System 4 in drier seasons.
Since 2008, there has also been an in-dairy feeding system available.
The systems trial about to start will involve 400 cows from the existing milking herd split into two treatment groups. One group will be managed along controlled duration grazing principles and making use of the freestall barn, while the other group of 200 cows will act as a control treatment using the standard feedpad and typical grazing management.
The cows involved are a mix of Friesians and Friesian/Jerseys. The two herds have been balanced for Breeding Worth and age. Once the trial starts the herds will effectively have closed membership though heifers will still be introduced annually as replacements.
How much time the cows will spend in the freestall barn will depend largely on soil conditions. The barn herd will be wintered on the platform and Christensen predicted they will spend a fair bit of time inside over this period, but will still spend time grazing pasture.
Over the spring period, it is likely barn visits will be overnight with daytime grazing to harvest the spring pasture flush. Christensen said over the late spring and summer period the cows will be outside, using the barn as a feedpad only, if required.
In the autumn, cows will be brought into the barn to rest and ruminate after grazing to reduce nitrate leaching.
Two management blocks on No. 4 have been allocated to each treatment group, meaning the two herds will have their own farmlets.
Milk production, animal health, somatic cell count, body weight and body condition score will be monitored along with regular locomotion scoring and monthly sterile milk sampling to help track and identify any pathogens.
Automated scrapers run every few hours down the barn aisles. Effluent from the barn is being captured in a newly constructed clay-lined storage pond beside the building, separate to the dairy effluent.
The slurry will be applied to the farmlet by tankers with the pond emptied two to six times a year.
“It will be re-applied as early in the spring as possible to increase pasture growth and recycle those nutrients more efficiently,” Christensen said.
“If you can increase the pasture grown, you can help pay for the structure.”
The barn – constructed to meet the highest welfare standards – cost about $1.4 million to build, and was completed late last year. The cows are being introduced to their new digs, getting ready for the systems trial to begin in earnest in the autumn.
The research is part of the Pastoral 21 programme, a collaborative venture between DairyNZ, Fonterra, Dairy Companies Association of New Zealand, Beef + Lamb New Zealand, and the Ministry of Business, Innovation and Employment. The venture’s aim is to provide accessible systems-level solutions to profitably increase pastoral production while reducing farms’ environmental footprint.
