21 Aug 2018
Making silage in late summer and into autumn - what to look out for
To reduce the impact of the dry summer as we head towards the winter months, farmers should be considering their options to make up feed deficits and ensure feed bills do not soar.
According to Dr Liz Genever, AHDB senior scientist, making silage later in the summer or into the autumn is possible, but there are a few things to look out for.
She says: “It can be more challenging to wilt the grass quickly as the days are getting shorter and temperatures are dropping. The target DM should be 28–32 per cent for clamp silage and 35–45 per cent for bales of silage. Rapid wilting ensures minimum losses in the field and better silage preservation.
“Later in the year, sugar levels in the grass are likely to be lower, so fermentation can be affected,” says Dr Genever.
“It is worth thinking about the use of a silage additive. It could be that if the crop is low in sugar and dry matter then an acid inoculant may be the best one, or a sugar supplement may be needed. Speak to your supplier for guidance.”
For those fields that have not had significant growth over the summer, there will be residual nitrogen (N) available to help regrowth once the rain comes.
There is some risk of luxury uptake once the rain does come which can lead to intake issues as well as concerns about grass staggers.
Growth
Dr Genever says: “It is likely that additional nitrogen will be needed to stimulate further growth, particularly if the intention is to cut silage or build covers for the autumn. The response rate to nitrogen will be dropping as we head into the autumn, and is likely to be around 10kg DM per 1kg of N applied.”
The recommendations for August application in the AHDB Nutrient Management Guide (RB209) is 30kg N per ha. For those grassland fields in nitrate vulnerable zones, the closed period for manufactured fertiliser is 15 September and for organic manures is 15 October.
If you have had to house stock then it may be an advantage to get organic manures spread to ensure space going into the winter.
Achieving rapid wilting
- Using a conditioner on the mower which splits the grass and increases the surface area for water loss. This can increase wilting speed by up to 20 per cent
- Leaving a stubble of at least 5cm to allow air movement beneath the lying grass
- Spread the crop quickly and over a wide area. Water loss is highest for the first two hours after
“It is also a good time to sort through stock and records to ensure poorly performing or unproductive animals are not kept on the farm,” says Dr Genever.
“There are challenges with getting some stock booked in to abattoirs and market prices are down for some categories of stock at the moment. However, at this stage all decisions will cost money, so it is about trying to find the one that costs the least.”
Some people are creep feeding to boost growth rates of calves and to take the pressure off ground and cows.
Depending on forage supplies, it may be worth weaning calves early, inside, on to their ‘winter ration’ to ensure good performance with the aim of building body condition score (BCS) on cows before the autumn. Carrying out a pregnancy diagnosis on cows will be crucial this year, as the heat could have affected cow and bull fertility.
In normal years, farmers would start creep feeding calves at around six to 10 weeks before weaning.
“This year, it is worth starting creep feeding earlier, at around 12 weeks, before weaning for bulls that will be finished on ad-lib cereal diets,” advises Dr Genever.
“With very milky cows or in situations where it is tricky to creep feed, starting four to six weeks before weaning will still help reduce the weaning check. As a rough guide, allow 100-150kg of creep feed per calf for a six to 12 week creep feeding period.”
For lambs, creep feed is being used to maintain growth rates and also to put some finish on lambs. Dr Genever says: “Most years it would be challenging to justify feeding high levels in the autumn, as price does not compensate for the cost, but this year choices are limited. In a normal year, if lambs have access to ad-lib with good grass, they will eat 40-50 kg per head. This year, that figure will be higher.”
Ewes in good condition before the dry period set in have managed to maintain that condition, but the thinner ones are struggling to build BCS. Dr Genver says: “You should try to segregate on BCS so that, if additional feeding is required, it can easily be allocated to the stock that need it.”
If thin ewes do not respond to additional feeding, then it is worth talking to your vet about testing for the ‘iceberg’ diseases, such as Maedi Visna and ovine Johne’s disease.
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