How maize is driving dry matter intake in NI dairy herd

Mixed farmer James Purcell farms in Limavady in partnership with his father, Ivor, uncle, William, and cousin, John.

See also: 6 top maize growing tips to help livestock producers

He had always wanted to try growing maize for their dairy cows since seeing it grown and fed when he worked in New Zealand.

However, he was worried it would not be possible because of ground type and the cost of establishment.

In the end, they decided they would never know unless they tried it. They drilled 4.5 ha (11 acres) last spring and plan to drill an additional 5.3 ha (13 acres) this year.

The 220-head predominantly Holstein herd is split into two management groups, with one grass-based herd milked through a parlor and another group of 65 cows fully housed in a robotic unit.

Keen to increase intakes and yield from forage, Mr Purcell decided to trial the maize with the latter group.

“It’s a good alternative to forage, it complements Northern Irish grass silages quite well.

“We’ve found it drives dry matter (DM) intake and that increases milk production and milk quality. Increasing the forage gives us the potential to reduce purchased compound too,” he says.

He has seen intakes raise by 4kg a head a day and estimates that daily milk yield has increased by 1.5 liters a head.

“Cows have got a real good shine on their coats, visibility from heat has drastically improved and butterfat and protein seems to be on the increase – everything to be ticking along a lot better than it was before the maize,” he adds.

© James Purcell

Nutritional management

Feeding began on 11 November 2022. The rationalization (see box) was carefully balanced with the help of the farm’s nutritionist and informed by analysis of the maize and second-cut grass silage included in it.

“We try to balance home-grown age to maximize efficiency,” explains Mr Purcell.

However, he had to reduce maize meal and introduce more soya into the rationale to avoid underfeeding protein and compromising on production.

“One option would be purchasing locally grown proteins or even trying to grow our own, such as beans and lupins, to partially offset our soya usage.”

Slight adjustment was also needed to the concentrate fed at milking time.

Before maize was introduced into the ratio, fresh cows would get a 16% protein nut and cows further into lactation would get an 18% nut.

However, the 18% nut needed switching to a 20% protein concentrate to maintain milk yield.

© James Purcell

Crop management

The maize crop was drilled under film on land that was previously down to Barley in April last year.

The ground was subsoiled, spread with farmyard manure, ploughed and power-harrowed twice. The seed-bed was then fertilized before the seed was drilled with a Samco maize drill.

“Once it was planted, we didn’t go in that gate again with a machine until it was harvested,” Mr Purcell says.

With an arable enterprise, they have the machinery to do all the ground work, but use a contractor to drill and harvest the crop.

There is no reason we can’t keep cropping the same area if we can keep compaction levels low – so I’m told anyway.

My plan is to grow in those fields for as long as possible. Down the line, we will probably go in with winter wheat straight after harvest because they say it does well after maize.

“There are no big areas of maize here. In a densely populated cow area, I think last year there were just three of us trialling it for a six-eight mile radius.”

They planted a mix of two varieties from Pioneer, P7326 and P7524: one for yield and one for quality, as advised by seed supplier Shine’s Agri.

The crop was harvested on October 20. Fortunately, the ground was hard enough to allow that, but Mr Purcell hopes to plant an earlier-ripening variety this year.

This is because in a normal weather year, he thinks even 10 days could make a lot of difference.

We reckon the better field yielded about 18t/acre [44t/ha] and the lower field was around 15-16t/acre [37-40t/ha].

“We’re happy with that, given our situation and incidence. The dry weather actually helped us – it takes a lot for us to dry out here,” he says.

The farm is mainly a mixture of clay loam and darker clay soils. “We do have some sandy loams but the fields are either not south facing or not accessible, so aren’t suitable for maize,” he adds.

The crop was consolidated in an indoor clamp and an additive was used to prevent spoilage. The walls and top were sealed with a cling film before using black plastic and rubber mats on top.

future plans

This year, the hope is that by doubling the crop area, Mr Purcell will be able to increase the amount of maize fed to 15kg a head a day next winter.

With soil erosion in mind, he is considering how he could use a nitrogen-fixing cover crop during the winter.

He says it will be trial and error for a few years, but he is hopeful that continued progress in the seed breeding sector might result in more varieties suitable for his farm.

“Ultimately, we aim to feed cows well to increase longevity and decrease cull rate, which I suppose helps to tick the carbon boxes too,” he says.

“Every day is a learning day and I’m glad I have used the advice we’ve had, even if they have been selling us something, because it’s easy to keep doing what you’re doing, but you have to take a risk every now and again.”

© James Purcell