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• Be prepared – clean the clamp, order the additive (if using), and service the machinery well before the anticipated cutting date to take advantage of a good weather window.
• Prepare the clamp with plastic side sheets and 2 top sheets – the lower one being the new type of oxygen barrier cling film.
• Start with a clean sward – no dead grass at the bottom and no slurry for 8 weeks before cutting (otherwise you have clostridia laden grass which makes a good fermentation difficult).
• Roll to supress stones and mole hills.
• Get fertiliser on early and test grass for nitrates and sugars if there is any doubt (guideline 2.5 units N used per day). Nitrates should be less than 1000 mg/kg and sugars more than 2.5% in the fresh weight to reduce the risk of poor fermentation.
• Aim to cut at 72 D value – leafy with some stem but no flowering stems – for every drop in 1 D value below this you lose 0.3 MJ ME.
• Cut in the afternoon (when sugars are significantly higher) with a mower conditioner and leave at least 6 cm stubble (10 cm if old leys). Chop length 2 - 2.5 cm.
• Spread within an hour (evaporation rate is 100 litres/t/hour in the first 2 hours and falls to 20 l/t/h after 4 hours) and aim to wilt to get DM > 25% (24 hour maximum).
• Avoid soil contamination during spreading and raking.
• Use an additive:
  • If slurry or soil contamination is a risk – use a chemical additive e.g. acid (e.g. formic acid), acid salt (e.g. ammonium tetraformate) or non-acid salt (e.g. sodium benzoate). The application rate is usually very high (4 l/t) and the cost is high so try to avoid contamination.
  • If clamp management is good – use a homofermentative inoculant e.g. Lactobacillus plantarum for the best possible silage (and cheapest additive). Homofermentative bacteria produce lactic acid from sugar, improve speed of pH decline and improve nutrient quality of silage. BUT if your clamp management is not good there will be more spoilage on exposure to air because there are more nutrients available for the yeasts and mould to feed on.
  • If clamp management is not good – use a mixed homo and heterofermative inoculant e.g. L. plantarum and L. buchneri. Heterofermentative bacteria produce lactic and acetic acids and other end products from sugar which will reduce silage quality but improve aerobic stability.
  • Homofermentative bacteria: L. plantarum, L. salivarius, L. casei, Pediococcus acidilactici, P. pentocaseous, Lactococcus lactis.
  • Heterofermentative bacteria: L. buchneri, L. brevis, L. colonoides, L. fermentum.
  • Check the amount of bugs – must be 1 million per g fresh matter or not worth using. At the correct rate you will get a more rapid fermentation and therefore preservation of more true protein in the grass and better animal performance.
  • e.g. 100 g bottle sufficient for treating 50 t grass has 2.5 x 1010 CFU/g This is 25,000,000,000 bugs so divide by 50,000 g grass = 500,000 bugs per g or half the effective rate.
  • A word about enzyme additives – these are designed to release sugar from the grass for the bacteria to use OR to improve the digestibility of the grass in the rumen by breaking down the cellulose. They are usually sold in combination with bacteria and are more expensive that a straightforward inoculant. They may work with a more mature crop but avoid using with low DM, lush crops.

• Fill rapidly and roll constantly. If you stop overnight, throw the sheet over with enough tyres to keep it on. Do not roll in the morning before the new loads of grass come in – it creates a bellows affect and sucks air in.
• Packing density has a huge effect on aerobic spoilage e.g. density of 160 kg DM/m3 – DM loss at 180 days post ensiling was 20% compared to 10% with a density of 320 kg DM/m3.
• Seal and weight down with rubber mats, gravel bags and if you really have to, tyres, but be aware that the wires in tyres are killing cows.
• Keep sealed for 6 weeks before opening.
• After all that effort make sure you keep the oxygen out once you open the clamp by keeping the face tight and moving back through the clamp at a fast enough rate to prevent spoilage.
• Think about the cost of making silage and how much potential loss there is from not paying attention to details throughout the stages. Stages in making silage Potential DM losses Field losses during harvest (field and filling) 2 - 12 In silo respiration and fermentation losses 5 - 18 Effluent 0 - 8 Aerobic spoilage 1 - 10 Total 8 - 48

Cutting down on DM losses is a good way to make more silage and reduce the cost of bought in feed. For every 100 t silage DM you make the difference between 10% losses and 30% losses is 20 t which at £100/t DM is £2,000.

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