Profiting from pastures

DPI scientist Joe Jacobs

At a glance

• Traditional perennial ryegrass based systems grow 60–70 per cent of their total annual production in late winter and spring.
• Extending the growing season through the use of complementary crops and forages could save costs.
• Double cropping can improve herbage yields by up to four tonnes per hectare compared to a traditional perennial ryegrass system, but will involve greater costs.
• A range of options exist to both increase the amount of grazeable forage grown and the amount conserved for periods when feed is in short supply.

Victorian scientists are finding new ways to improve the performance of perennial pasture systems through the use of alternative complementary forages.

DPI scientist Joe Jacobs said the research focussed on complementing perennial ryegrass based pastures, not replacing them.

“Perennial ryegrass pastures are a very robust system and when they grow the energy and protein contents are ideal. The research is about how we can find species that complement ryegrass at key times,” he said.

Dr Jacobs said options like double cropping or extending the growing season could make a real difference to the bottom line.

Perennial ryegrass

Dr Jacobs said Victorian dairy farmers traditionally relied on a perennial ryegrass based system.

And while this has real advantages it also has its challenges.

“But it has low growth in the middle of winter when temperatures are low and the soil gets waterlogged, and in summer when there’s no moisture for growth.

“Under dryland conditions it grows 60–70 per cent of its total annual production over the three to four months in late winter and spring, which means we have to transfer surplus feed to other times of year.

“This results in additional costs, including making and feeding out the silage or hay and you run the risk of losses of dry matter in the process itself.”

Dr Jacobs said the project team had two main challenges when they set up the project. The first was finding alternative forages that could complement the perennial ryegrass in terms of dry matter production but also meet the energy and protein demands of a lactating animal.

“The second one was if there aren’t the grazing options around, then can we grow even more in spring and make more hay and silage, but still minimise cost and losses of dry matter?”

Dr Jacobs said the team investigated options that could fill the feed gaps in the growing season, initially focussing on what could be grown from late spring through summer to fill a key feed gap created with the current perennial ryegrass based system.

Growing longer

Dr Jacobs said chicory and plantain were of interest because they could be established in spring and could grow significant amounts of valuable herbage during summer.

He said another advantage with these type of crops was farmers don’t need to apply a herbicide when re-establishing a perennial ryegrass pasture the following autumn.

“We have found that we can grow a range of different species on top of them including perennial ryegrass, annual ryegrass, Italian ryegrass and winter cereal crops.”

He said that trials carried out to date at the Terang Demo Dairy in western Victoria had proved successful.

“Both chicory and plantain grew well over the first summer after establishment and into autumn, then over winter and early spring they tended to be slower than other species.

However, in late spring when the grasses are starting to slow in growth, both chicory and plantain fired up again and managed to extend the spring growth into late January.”

Figure 1 highlights the different growth patterns of chicory and plantain compared to perennial ryegrass.

FIGURE 1 - Growth rate of chicory, plantain and perennial ryegrass

Dr Jacobs said extending the growing season like this could be a real advantage.

“If we get these species to grow very well into January and February, we are able to get up to an extra two months of high quality grazeable feed which in turn can reduce the reliance on supplementary feeds,” he said.

Work is continuing to evaluate the fit of both chicory and plantain into grazing systems, with feeding studies planned in the coming years.

Farmer take up

Chicory

Plantain

Dr Jacobs said that some farmers were already starting to grow chicory and plantain.

“It’s gaining interest, but at the moment they’re probably waiting for us to iron out some of the challenges.”

There were currently very few herbicide options to remove weeds when establishing a chicory or plantain crops so the seedbed needed to be clean when sowing.

Fortunately, neither species was as vulnerable to insect attacks as Brassica forage crops which make them an ideal summer forage option.

Their main competition came from broad leaf weeds, Dr Jacobs said.

“A bit of planning is required to take out those broad leaf weeds before you sow the chicory and plantain.

“The flipside is they grow well with clovers. We have seen that the current perennial ryegrass systems under intensive rotations are not conducive to clover remaining in the sward (upper layer of soil).

“These chicory and plantain options do provide an opportunity to have clover back in the system, which we know can fix nitrogen and in turn supply that to other species in the mix.”

Double cropping

Another option considered was double cropping using combinations of summer and winter forage crops.

“If we can’t grow more than the traditional existing option then we have to question why change at all,” Dr Jacobs said.

“The herbage dry matter yields ranged from 27–39t dry matter per hectare (DM/ha) over the two and a half years that the experiment ran.”

Figure 2 presents data from selected treatments.

FIGURE 2 - Dry matter growth comparison

“Over two and a half years the perennial ryegrass drew 33.5t DM/ha,” Dr Jacobs said.

In another treatment, the team grew a chicory/plantain and red clover mix in spring and grazed this over summer.

It was then over-sown with winter wheat in autumn, grazed in early winter before being locked up for silage and cut in October.

The chicory/plantain mix then re-grew through summer and was grazed numerous times before again being over-sown with winter wheat in autumn and the same process followed.

This combination grew 37.5t DM/ha over the same period as the perennial ryegrass treatment.

“We actually grew four tonnes more than the perennial ryegrass,” Dr Jacobs said.

“But this did come with the additional cost of sowing the winter wheat in each year.

“The challenge is to determine whether that is cost effective for an extra four tonnes?”

Dr Jacobs said that using total yields are a good initial comparison but it could also be misleading.

“This information doesn’t necessarily tell you when it was grown and one of the goals is to grow additional feed when perennial ryegrass is not able to.”

Total yield results also overlook the quality of the extra feed.

Increased silage

Grazing chicory in January

Dr Jacobs said another option under investigation was to increase the amount of silage made in spring by growing even more at this time of year.

“Can we find other species that can grow even more in spring so we end up making more silage that we can feed back at other times?”

This area of work has focussed on forage cereals, in particular winter wheat and triticale.

Oats were studied initially but this species tends to lodge (lean) which makes it difficult to ensile (make silage).

“The aim was that we would sow these cereals in autumn and maybe get an early grazing off them in early winter, when the cereals got to mid tillering,” Dr Jacobs said.

“At this stage you can get a light grazing and this won’t have any detrimental effect on subsequent regrowth.

“If you’re going to graze you’ve got to do it at the right stage.”

Dr Jacobs said growth rates from both species had been “phenomenal”.

Metabolisable energy content was less impressive.

“If I was thinking of silage I could feed back to a lactating cow, I’d want 10MJ/kg/ DM of metabolisable energy, with a crude protein content above 15–16 per cent. That would be my ideal,” Dr Jacobs said.

“With these winter cereals we are finding that silage made at the soft dough stage of growth has a metabolisable energy of between 8–9MJ/kg/DM and a crude protein of between 9–10 per cent. That’s not good enough to be considered as a major part of a ration for a milking cow.”

Improving cereal silage quality

Chicory and plantain growing with winter wheat prior to harvesting for silage

With the challenge of low metabolisable energy and crude protein, research then focussed on finding a companion species to grow with the cereals that would not result in a drop in herbage dry mater yields but would improve the quality.

One option is to grow a legume such as field peas.

“We conducted a series of trials over several years where we included peas at different rates in the sowing mix,” Dr Jacobs said.

“We either sowed straight triticale, wheat or peas then we had options where 25 per cent, 50 per cent and 75 per cent of the sown mix was peas.

“The good news was that including peas in the mix did not reduce herbage dry matter yields, but it had only a marginal positive effect on energy and protein levels when sown in mixes with the cereals.

The peas struggled to compete with the cereals.

“With the triticale, even when 75 per cent of the sowing mix was peas, they accounted for less than 10 per cent at harvest,” Dr Jacobs said.

“Wheat was a bit better at 20 per cent, but not enough to have a significant impact on the metabolisable energy and crude protein levels.”

Dr Jacobs said the peas grown on their own did well.

“Over the two years a straight pea crop yielded 11–12t DM/ha and had a metabolisable energy of 9.5–10MJ/kg/DM and a crude protein of over 15 per cent.

“The yields weren’t as high as the cereals but they were high enough to make this a viable option on soils that do not waterlog over winter.”

More recently the research team has also investigated a range of other legumes including vetch and annual legumes as potential candidates to grow with winter cereals, with both balansa and Persian clover showing some promise.

Future studies

Dr Jacobs said there was another potential advantage of finding higher quality forage options — lower methane emissions.

“If we can provide high quality grazeable feed pretty much all year around, we could be in a position to contribute to reducing methane emissions from grazing systems.”

Dr Jacobs said as well as reducing emissions through the provision of high quality feed, some forage options such as chicory and plantain contained secondary compounds that could also inhibit methane emission.

“That’s where we’re hoping to take some of this work into the future.”