Choosing grass mixtures is all about balance, says Limagrain’s John Spence.
New research has enabled plant breeders to test grass quality in more depth and provide nutritionally balanced mixtures.
Farmers are careful to balance cows’ diets when they are housed over winter – and they should be doing the same when choosing which grass mixtures to grow, according to John Spence, seed sales specialist at Limagrain.
Until recently, that has been quite hard to do, but new research has enabled plant breeders to test grass quality in more depth and provide nutritionally balanced mixtures, leading to improved milk production at minimal cost.
Mr Spence says: “There are two possible routes to improving animal performance through feed: Higher intakes and increased nutritional value. Most grass mixtures on the market are chosen on agronomic features alone, but now there is the option to include nutritional features as well.”
Analysis techniques like near infrared spectroscopy are now being used more widely to provide in-depth feed quality and comparative data across the whole growing season. This additional testing on grass varieties means feed quality can be more accurately determined. Plant breeders can therefore develop mixtures which offer not only good agronomic features, but which also have the potential to improve feed quality and promote more efficient milk production.
Limagrain Animal Nutrition (LGAN) accreditation is only added to varieties and mixtures which are proven for their efficient production and contribution to animal performance, says Mr Spence.
“We use new varieties with improved digestible neutral detergent fibre [DNDF] as well as more palatable tetraploid varieties which the cows will graze in preference to diploid grasses. If varieties are digested more efficiently, intakes will improve, with resulting nutritional benefits.”
Fibre is needed in the diet to maintain a healthy rumen, but varieties with low levels of DNDF slow down the digestion. “If we can increase DNDF in the diet, then feed efficiency is boosted and this can lead to improved yields,” adds Mr Spence.
Research from Michigan State University has shown that even a 1% increase in digestible fibre leads to a 0.17kg/day improvement in intakes and 0.25 litres/day more milk.
When putting together a mixture with feed quality in mind it is all about finding the right balance between fibre, protein and sugar content.
“Some grass varieties will be high in sugar but low in protein, while others will be high in protein and low in digestible fibre – you’ll never get one variety which offers the best of every world,” says Mr Spence.
JLimagrain has developed grass seed mixtures which have the LGAN accreditation with a range available through its Sinclair McGill portfolio. These comprise a dual-purpose silage and grazing mix; an intensive grazing mix formulated to maximise voluntary intakes; and an extended grazing mix which includes a New Zealand variety, Matrix, to give a longer grazing season. The silage options comprise a high energy mix or a high protein mix featuring red clover to reduce the need to feed supplementary protein in the diet.
“That’s why it’s important to select complementary varieties within a mixture which are nutritionally balanced as well as having the necessary yield and agronomic attributes. There’s no point sowing grass which is nutritionally perfect if it doesn’t have good ground cover, persistence, yield and disease resistance.”
Although the Recommended List (RL) does focus on the agronomic features of different varieties, it does not contain much information about their nutritional profile – but independent trials in the UK and further afield have produced some exciting results.
“We’ve found there is a big variability between varieties: A range of 1.2MJ of ME/kg, a 5% difference in sugar, protein content and D Value, and a 10% variance in digestible fibre,” Mr Spence explains.
“This would translate into potentially big differences in feed efficiency and production from forage.”
Trials conducted at NIAB TAG, Dartington, Devon, compared popular grass mixtures containing RL varieties with the LGAN Intensive Grazing mix. Results revealed that the Intensive Grazing mixture produced 10% more energy (see table, above) than the control. The yield was 0.9 tonnes/ hectare higher, at 11.3t/ha, and the nutritional quality was better across the board.
“It produced 13,529MJ more energy/ha – enough to produce 2,553 litres of milk,” says Mr Spence. “With a milk price of 23ppl, that’s worth £587/ha.”
Unlike the RL trials, where forage quality is determined from just two cuts, the Dartington trials measured forage quality at all cuts throughout the growing season, thereby demonstrating the growth profile of the different mixtures.
“The Intensive Grazing mix delivered up to 140MJ/ha more energy – equivalent to 26 litres of milk,” he explains.
Animal feeding trials at Schothorst in the Netherlands have proven the link between improved grass nutrition and higher milk yields, comparing a conventional dual-purpose grass mixture with a nutritionally balanced mixture. The LGAN grass seed mixture had a 3% higher ME and D Value, at 12.8MJ and 79.7%, respectively. DNDF was 8% higher, at 77.9%, with feed efficiency up 5% to produce 1.30 litres of milk per kg of feed.
“Milk yields showed a 5% improvement, at 29.9 litres a day,” says Mr Spence. “Assuming a 300-day milking period and a milk price of 23ppl, that’s worth nearly £10,000 to a 100-cow herd.”
Selecting improved grass seed mixtures is important, but grassland management – in particular a reseeding programme – is crucial to grassland feed efficiency.
“Farmers have been reluctant to invest in reseeding when margins are tight. But poor grass from old swards holds back grass quality and production,” warns Mr Spence.
According to Defra’s land use survey, the amount of temporary grass (under five years old) reduced from 1.396 million hectares in 2014 to 1.145m ha in 2016.
“This indicates a reduction in the amount of reseeding taking place at a time when livestock farmers should be trying to achieve more production from forage.”
Research by Shalloo et al (2011) showed grass utilisation increases proportionately to the amount of the farm reseeded each year, and net profits track the rising utilisation (see graph, below).
“The older a ley, the lower its dry matter yield and the poorer its quality,” he says. Based on AHDB Dairy data, a two-year-old ley yielding 13.5t/ ha at 12MJ/kg ME will drop to 11.2t/ha and 11.5MJ/kg by year five. By year 11, this will have dropped to just 7t/ha at 10.8MJ/kg.
“The milk losses from that equate to 4,698 litres/ha by year five and 12,226 litres/ ha by year 11 – and the cost of replacing that energy by feeding concentrates instead would be £491/ha and £1,279/ ha, respectively.”
When assessing pasture, farmers should consider reseeding if productivity has fallen, the proportion of sown species is below 60%, there is a high weed burden, or significant evidence of compaction.
“Select your grass mixture based on the target use of the pasture, as well as considering its agronomic and nutritional balance,” Mr Spence says. “The total average cost of reseeding using full cultivation is £689/ha, so carry out a cost-benefit analysis and see how much better off you could be by investing in your pasture.”
Getting more milk from grass is all about farmers changing their attitude, according to independent nutritionist Diana Allen.
“We’ve seen the potential, and there are lots of good practical resources out there to help, so if you want to improve your grassland management you just need to get on and do it,” she says. “Go and see what other people can achieve and it will change your mind.”
The two most important elements are measuring and monitoring grass growth and quality, so farmers should start by investing in a rising plate meter and a grass management programme, advises Mrs Allen.
“You could get 20% better grass utilisation just by measuring and monitoring – and if you’re reseeding as well it’s not unusual to get a 50% uplift.”
Farmers should plan to reseed a certain proportion of their grassland each year, and then monitor pasture to check whether it needs replacing yet or not.
“The best measure is the weed burden – if you have 10% weeds that means 10% less grass – and it’s not unusual to find 20-30% weeds in a sward.”
When choosing grass mixtures, it’s important to realise that grass breeding has moved a long way in recent years, she adds.
“Newer varieties, when wellmanaged, have much higher forage quality than older varieties, which really are outdated now. But as with any grassland it must be managed well.”
Mix it up
In general, plant breeders have moved either towards high sugar grasses or highly digestible grasses, and Mrs Allen suggests using a mix of different varieties to balance the quality and spread the risk.
“If disease or competition wipes out one variety you still have the others to fall back on.”
The quality of grass varieties is also critical. “A 1% rise in D Value will increase milk yields by 5%, which is significant.”
Farmers should also choose grass mixtures based on their own production system and whether the pasture is destined for grazing, silagemaking, or both.
“If you have the right land to take an early first cut of silage you can have more early heading varieties in the seed mixture.”
Getting more milk from forage is possible, and highly influential on the bottom line, whether the system is fully housed or extensively grazed, she adds.
“There’s no doubt homegrown forage is critical to profitability.”
Treat grass like a crop
The important thing is to treat grass like a crop, and consider its nutritional benefits in the same way as silage in a ration.
“If you’re rotational grazing you can get consistently good ME; if you manage your grass well the only fluctuation you’ll get will be dry matter as it’s so weather dependant.”
Decent grass producers will consistently achieve 12MJ/kg ME at 17-20% protein throughout the grazing season, while a good silage target is 11.5MJ/ kg ME at 16% protein and with a D Value of 72-73.
“The target volume of milk produced from forage will depend on whether you’re producing white water or high solids, but you should aim for each cow to eat 14kg DM of forage per day, whether that’s grazed or ensiled,” says Mrs Allen. “If it’s silage you’ll probably need two silage types to reach that level of intake, so perhaps use maize and grass silage together.”
Farmers should take advantage of the latest grassland research and new developments, she adds.
“Grass utilisation in this country is a lot lower than it should be. The absolute key is to get your grazing management sorted and pay attention to every detail.”