With shredlage production the crop is harvested earlier and the process involves a combination of a longer chop length, rolling of the grain to crush the kernel and lengthwise shredding of the stalk. Typical chop length will be 26-30mm compared to 20-25mm without shredding using a traditional forager. It is claimed this intensive processing bring a range of benefits.
It reportedly improves the physical effectiveness of maize in the rumen by improving fibre digestibility and encouraging rumination. Trials at the University of Wisconsin showed increased milk yields with typical US diets.
One of the reasons for the yield response is the greater chop length and physical processing of the chopped material. With typical US diets comprising up to 70% maize silage in the forage portion of the diet, the chop length of maize will have a marked effect on overall rumen health.
Under UK conditions, diets usually contain a lower proportion of maize, commonly 30% maize: 70% grass. As grass silage will already have a longer chop length than maize, the impact on rumen health and yield of increasing maize chop length may be less significant.
However, it is likely the approach will be on interest to UK producers, particularly those feeding a higher proportion of maize in the diet.
Although shredlage involves a different processing stage at harvest and may have implications for harvesting dates, Tim Richmond, Maize Manager with Limagrain UK does not believe it fundamentally changes the principles of variety selection, saying that the decision to take a crop for shredlage is more about harvesting stage and management than variety.
“While shredlage processing will have an impact on digestibility of fibre, don’t be tempted to chase higher yields by growing a lower quality variety,” he comments. “Any improvement will be incremental from the quality of the original plant and the aim should be to grow the best quality crop possible, particularly where it is not certain whether the crop will be taken as shredlage or traditionally harvested.”
He says the first priority should still be to select a variety from the BSPB/NIAB Descriptive List which is agronomically suited to the farm. “First and foremost varieties grown must be suited to the site class to increase the prospects of a high yielding quality crop.
“Once a short list of varieties has been produced, then select the ones which will produced the highest yield of quality forage, irrespective of how it is harvested. This will mean focusing on dry matter yield, starch content and cell wall digestibility (CWD).
“As half the total energy is in the leaf and stover, it is the combination of starch content and CWD that drives total ME. So farmers should look at both starch content and cell wall digestibility (CWD) when selecting the varieties to grow if they want to maximise effective energy yields and production from forage.”
He suggests the processing in shredlage production can be seen as a mechanical way to improve fibre digestibility, but argues that selecting a variety with good CWD is the best starting point as the benefits will be seen in traditional silage as well as shredlage.
To help growers through the decision making process Limagrain introduced the Limagrain Animal Nutrition (LGAN) Accreditation scheme, the first scheme which identifies varieties with the combination of attributes that will deliver superior milk production.
“LGAN accreditation is a farmer’s assurance that the variety selected will deliver higher yields of digestible energy from both starch and the cell wall, leading to increased feed intakes and better production. To achieve LGAN status the variety’s performance must be outstanding compared with average varieties that have been on the NIAB list at least four years.
“Don’t assume that mechanical processing will improve quality to the extent that a poorer variety is bought up to the level of a high performing one. If you grow a poorer variety and then don’t take it as shredlage you will be left with a lower quality feed. Selecting a better quality cultivar will mean you have a higher quality feed, however it is eventually harvested.”
Mr Richmond says that in the US shredlage will typically be taken earlier than a normal silage crop, being harvested at the half milk line stage, when half the kernel is milky white. He comments that normally maize will be harvested in the UK when more mature, with less than 25% of the kernel still white.
“This ability to harvest sooner may provide more flexibility and widen the harvest window. A proportion of the crop could be taken sooner to allow a successor crop to be established earlier. Cutting sooner could also allow maize to be introduced into the diet more quickly.
“However, harvesting early can have a significant impact on feed quality. Starch deposition occurs in the last few weeks before harvest, typically between September and mid-October, alongside increases in dry matter content. Harvesting too early could reduce starch content by over 5%. Therefore it will be important to select early maturing varieties that can achieve a minimum 28% starch by the earlier desired harvest date.
“It is likely that shredlage will offer some advantages to some herds but is unlikely to be a widespread approach, at least initially. Farmers tempted to try the system should establish the foundations by selecting varieties that will deliver high quality forage, irrespective of how it is harvested and so keep their options open this season,” Mr Richmond advises.