Friday, March 29, 2024

Mowing for growth

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Nelson farmer Brian Dineen has been experimenting with mowing. He told Anne Hardie carefully planned mowing not only improves cow performance, it’s also helping with weed control.
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As soon as pasture gets to more than 3200kg drymatter (DM)/ha, Brian Dineen mows it in front of the cows. Some paddocks get mown three times through a season.

Last season he mowed about 300ha of the 128ha Nelson farm where he and his wife Hannah have a 50:50 sharemilking contract milking about 400 cows at the peak of the season. By the end of the season they had produced 180,000kg milksolids (MS) – just over 1400kg MS/ha – and are targeting 185,000kg MS this season. And he attributes part of their good production figures to strategic mowing.

The Irishman who came to New Zealand to play rugby, trained as a pilot and then got a job relief milking on a dairy farm when pilot jobs were few and far between, now sees farm ownership as the goal. So he questions and analyses every method to increase production and particularly profit to reach that goal, including mowing.

It’s the Dineens’ third season on the farm, which lies near Tapawera and belongs to Evan and Adrienne Baigent. Brian says they are fortunate to have farm owners who let them trial new ideas and he’s used Evan as a mentor in their dairy business.

Sharemilking followed a rapid rise through the industry from six months as relief milker to a year as farm assistant, two years 2IC and then 50:50 sharemilker.

The couple employ two staff to help run the farm, which is irrigated by pivots and sprinklers, with about 10ha non-irrigated. By midsummer, temperatures reach the mid-30s. They alter milkings to 5am and 1pm and choose paddocks with shade for daytime grazing and paddocks without shade for night grazing.

It suits the farm and works for them which is a philosophy Brian applies to all his management decisions, including the mowing.

“It’s not one-shoe-fits-all and it works for our system. We want the cows always going on to high-quality grass and that’s what we do to achieve that. We’re looking at getting the best out of our grass when we put our cows in the paddock.”

Their interest in pre-mowing grass for the cows began on the farm they worked on in Canterbury where mowing was purely experimental. 

“And it got me thinking. I noticed the spike in the milk when we did mow and I thought we wouldn’t have to spray for thistles. When we came up here I found if we mowed at lunch time, we got that high sugar content.”

Last season milk production reached 2.6kg MS/cow/day and Brian is convinced the mowing played a big part in it. They also fed the cows 195 tonnes of palm kernel through the season, especially when feed got tight in summer despite irrigation, but dropped the palm kernel on days they were mowing because the cows didn’t need it then.

Despite the lower payout, he intends to continue strategic mowing this season at a cost of $29.50 an hour. He uses a Pottinger mower which gets a new set of blades each year and can be used to cut silage as well.

If a paddock gets beyond 3200kg DM/ha, they mow in front of the cows to retain quality and feed the cows more. To keep pasture quality through the season they also post-graze mow if the cows – which are stocked at 3.2 cows/ha – have left clumps. It depends on the individual paddock. Some paddocks might never be mown and others are mown three times through the season.

Last season they began pre-graze mowing towards the end of August and continued until Christmas. They post-mowed again at the end of January for grass quality and later in February when rain started coming through again. A later start to the growing season this year meant they didn’t start mowing until mid-September.

“We fully agree that you can train your cows to eat whatever residual you want and in spring you can lock it up for silage, but we can also mow in front of the cows and don’t have to make silage. This year we may make more silage on the farm in case an El Nino happens and that may change our strategy so that we lock up paddocks instead of mowing them and putting the cows in. Though our preference would always be putting the cows in for production.”

Brian has noticed the cows are getting better at eating the mown grass.

“They’re like athletes really. The harder you train the better you do. And now when they go into a mown paddock they’ll just deck it. They just hoover it up like noodles. In the beginning some weren’t sure and would eat around the corners of the paddocks. And some still prefer that, so this year I’m thinking about mowing in lines and may mow 80% and leave 20% for those cows which will cut down the costs of running the tractor.”

Both the mower and the cows leave residuals of 1500-1600kg DM/ha and during the flush of growth the mower guarantees that constant residual for quality, Brian says.

“We’ve tried putting cows back in paddocks to push them to clean up and we’ve found they don’t do so well. It’s just more work. Whereas I can mow and don’t have to go back in to spray or grub thistles.”

Instead of mowing, he could lift cow numbers from the 400-410 Friesian cows milked at the peak of the season, and add more supplements. But the system is working well for the amount of feed the farm grows without putting pressure on anything, so he doesn’t see the point.

In Brian’s first season on the farm, they dropped to 16-hour milkings in April, but last year brought it forward to mid-January because of the dry and then once-a-day milkings by mid-April before drying the last cows off in the last week of May.

“We lost milk and we still managed 180,000kg MS and I think the mowing early in the season really helped that.”

The challenge at the end of the season is getting the balance right between drying the cows off and ensuring a cover of 2300kg DM/ha going into winter, though this year they had 2500kg DM/ha on hand for the beginning of calving.

“We like having that high cover and I’d rather have too much than too little.”

Getting pasture management right is a team effort and mowing is just part of the equation. The team includes 2IC Adam Schultz and farm assistant Luke Mill.

“They both have to be able to do the same job I can do. You have to have your staff up to speed and every Monday we take turns to take a platemeter over the whole farm which takes an hour and 50 minutes. And all three of us do it together now and again and borrow a second platemeter to check we’re the same. It gives us a chance to discuss the pasture and you can talk about grass species, nitrogen and clover content.

“If everyone is on the right page and you get it right out there, it’s going to make you money. Young guys get a bad rap sometimes, but you have to teach them. If these guys make a mistake they’re invited in to lunch and we’ll go through what it cost. If they don’t look at the grass as the cows are coming out, we go back out and look at the grass and how to fix it because you have to not only make that money back, but look at what you can do to get ahead. As soon as you bring a monetary value into it, it gets them thinking about the job at hand and what’s at stake. They’re not always going to be a 2IC or farm assistant, so it’s important for them to know what’s going on and it means we open our books more to teach them.

“You want them to be able to stand on their own two feet and challenge the system. Otherwise you stagnate. These guys now quiz me and we have good debates about what we are doing.”

All the team can input the data into the Minda Land and Feed programme using their cellphones while they’re in the paddock. It’s the second season they’ve used the programme, which records pasture cover, fertiliser, irrigation and other factors to help in pasture management. It’s also an easy way to show staff how the pasture management is working and discuss what is happening.

“It’s solid evidence and a very honest way of showing what’s happening. But you’ve still got to go out and look at all the different aspects of the pasture.”

As well as using Minda Land and Feed, grass samples from under-performing paddocks are sent to the Dairy Business Centre to identify and rectify any problems.

Pastures vary around the farm to suit each irrigation system or dryland growth, focusing on different heading dates so they can manage the paddocks effectively. New varieties are constantly being tested to see how they perform through dry summers.

About 80-85kg/ha of urea is spread
on the paddocks after the cows in
various brews and mixes. One of the team heads out once a month and spreads it over five or six paddocks and Brian says it seems to get a good response.

Last year 7ha of Barkant turnips was added into the summer feed equation and this year it has increased to 10ha, though Brian is mulling over the idea of using some chicory to save costs while the payout is low.

“We can get a couple of grazings of chicory with its long tap root and more grazings will save costs of putting it back into grass so soon.”

Brian says the drop in payout is a good teacher for pasture management, forcing everyone to become more focused about growing grass for production.

“At $8.40 you don’t have to change anything, whereas now you have to look at everything. The word resilient has been overused, but it can create opportunity.”

That’s why they do things differently, like the mid-day milking in summer and the shade paddocks. The latter is considered vital.

Half the farm has tall shelterbelt trees and sprinklers are used on that area, while the other half has the pivot. In summer, the cows are milked at 5am then head to a shade paddock. They’re milked again at 1pm, and even 12.30pm depending on the heat, then head to a night paddock as the day cools.

It’s worked well and Brian says the cows are happier. The mowing has also helped cow condition because cows manage a big intake of food in a short space of time which takes less energy.

Rules of strategic mowing

  • Always let the cows graze it first if you have it right. But if the cows leave clumps, top it.
  • Top any clumps or high residuals left after grazing. If you can’t mow the paddock, use the cows to clean it up, but expect lower production and performance. Aim for 1550-1600 residuals with the mower.
  • Mow excess feed in front of the cows only if it feeds more than 200kg DM/ha than cow requirements and if there is quality feed down to 1550-1600 residual. If there was a poor-high residual or weeds on the last round, it’s better to let the cows take the best of it and then top behind. The cows can then graze to the correct residual on the next round, or you can mow in front on the next round if there is excess feed.
  • Cost of mowing works out about $50/ha including labour, fuel, depreciation and other costs. Mowing can be more profitable than forcing the cows to clean up a high residual because there is a labour cost in shifting cows to clean up paddocks and the likelihood they will not be grazing the next paddock in the round at optimum timing either. The cow’s milk production, hoof health, condition score and reproduction targets will also be affected if they are not eating enough of the highest quality feed and that is a cost to the business.

Reference: Boyce, P.B.; Kerr, G. (2013). Is Mowing Cutting Management?, SIDE Proceeding 2013

Brian (centre) discusses pasture with Adam Schultz (left) and Luke Mill.

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