Choosing the right varieties of maize to facilitate early harvesting, while also maximising yield and feed value, is essential to maintain herd performance and minimise damage to soils.
Brian Copestake, LG UK and Ireland sales manager, says the new early maturing varieties of maize from LG yield more and analyse at significantly higher energy levels than the average from the NIAB Recommended List.
He says: “By growing one of the newer varieties, such as LG Saxon or LG Conclusion, farmers will gain an increase in energy value of more than 6.5 per cent.
“To replace this difference in energy value per hectare between one of the average maize varieties on the NIAB list and the new LG variety, Saxon, a grower would need to buy-in the equivalent of an extra 12,700 MJ of metabolisable energy [ME]/ ha.
This is equivalent to buying-in an extra tonne of wheat/ha of maize grown.
“Furthermore, the cell wall digestibility [CWD] of these new varieties is considerably higher than the older ones, meaning the energy in the vegetative part of the plant is more readily available to the cow.
“Not only does this contribute to the increased energy content of the crop, but it also means the maize is much easier for the cow to digest.
“For example, the CWD of LG Conclusion and LG Prospect is 61.8 and 61.2 per cent, respectively, meaning maize silage made from these varieties digests more rapidly in the rumen and the cow obtains the energy more quickly.
In turn, this promotes higher intakes of forage.
“These new varieties are mature when they are still green and so when they are harvested and ensiled they are fresher and smell sweet so are more palatable, meaning cows will eat more.”
Mr Copestake adds the importance of early maturing has been illustrated by the last two consecutive autumns, where the weather has turned wet in early October, making maize harvest after this time extremely challenging.
He says: “On favourable sites, early varieties, such as Resolute, Conclusion and Gema, were usually ready for harvesting in mid to late September last year.
“Not only does this early harvest date mean the maize is in the clamp and will be ready for feeding sooner, but it also means the risks of late harvesting of maize are avoided.
“Harvesting maize when ground conditions are wet leads to compaction and can result in soil loss.
Furthermore, leaving soils bare over winter is entirely unacceptable, so harvesting early means it is possible to establish either a grass ley or a cereal crop before the winter.
Table 1 shows the difference in yield, dry matter [DM] and feed value of LG Resolute, a variety first listed in 2020 compared to the same data for established varieties first listed in 2014.
“These figures show that new varieties, such as Resolute, deliver greater performance potential than older varieties, alongside all the advantages of early maturity.
“Add to this the increased CWD, starch and energy value and it is clear for a small additional investment cost of between £12-£20/ha, there is no reason to choose older varieties.” As farmers begin to plan ahead for the coming maize planting season, it is vital they consider carefully how much maize they need to grow to ensure they have sufficient stocks to feed throughout the year.
Depending on the variety they plan to grow and the yield and feed value, farmers should budget carefully, taking into account the likely losses of maize in the field and in the clamp.
This is according to Roy Eastlake, technical support manager with LAN UK, who points to the importance of planning ahead to ensure a consistent diet for dairy cows.
He says: “Accurately accounting for maize silage losses when planning how much to grow so there is some of last year’s maize crop left over is strongly recommended.
“Figures from the top performing farms suggest the level of overall loss of maize from the point where it is growing in the field to where it is fed out to cows is about 12 per cent.
“This can be as high as 30 per cent for poorly managed silage harvesting and feeding, so it is important farmers plan to grow around one-fifth more maize than the quantity they want to feed in order to have the desired amount in the ration throughout winter.” He points to the newer varieties of maize which yield better and have a higher energy value.
Growing these varieties means a reduced area could be necessary to grow the required amount of maize silage to provide sufficient feed value.
Where farmers only have a limited area of land which is capable of growing maize, selecting a high yielding maize variety with high ME is advisable, he says.
Mr Eastlake advises taking an initial sample of maize silage for analysis two weeks after clamping and then analysing every month thereafter because this will highlight the changes in starch degradability through the year.
He says: “The starch in fresh maize silage is surrounded by a protective protein layer which makes the starch less digestible in the cow’s rumen.
This layer is broken down over time by the fermentation acids in the silage, but this process takes several months.
“Once the protein layer is broken down, starch is much more available for digestion in the rumen.
The increased starch degradability will increase rapidly fermentable carbohydrates in the rumen and could affect the diet balance leading to a reduced rumen pH.
Ensuring the ration is balanced correctly will help avoid a potential acidosis risk.
“Storing the maize for a few months before it is fed should prevent these sudden changes in starch availability.
This will not only improve diet consistency but it also helps reduce clamp losses because the fermentation process is improved and there is less aerobic spoilage.
“Using a crop specific forage inoculant, such as Lallemand Magniva Platinum Maize, as part of the best harvesting and feeding management, can save £10,000-£24,000/year for a 200-cow unit.
This is because of improved silage quality resulting in less wastage and lower purchased feed costs.”
TABLE 2: Range of losses measured from good/poorly managed silage production
Making silage is a biological process, so there will inevitably be a proportion of dry matter (DM) losses.
Assume a 200-cow herd requires an estimated 1,300 tonnes of fresh maize silage for the winter ration and summer buffer feed combined.
Typical yields of maize are 43t/ha (17.4t/acre) fresh weight or 13.76t/ha (5.57t/acre) DM.
The farmer budgets growing 30ha (74 acres) of maize to give 1,290t total fresh weight or 412t of DM (source: Maize Growers Association).
But is this sufficient? Table 2 uses figures from extensive trial data showing average losses when making maize silage comparing good and poor standards of harvesting, clamp and feeding management.
After losses are taken into account, farms considered to be in the ‘good management’ category must grow an additional 3.4ha (8.4 acres) of maize to make up for losses and achieve their target tonnage fed.
Farms in the ‘poor management’ category should be growing an extra 11.6ha (28.7 acres)
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