Making grass silagefor Better Returns

BEEF AND SHEEP BRP MANUAL 5

-

The information in this booklet has been sourced from: The GrasslandDevelopment Centre and IBERS, University of Aberystwyth; the SilageAdvisory Centre (www.silageadvice.com); Kingshay Forage Choice,Costs and Rotations Report 2010; British Grassland Society;www.silagedecisions.co.uk; DairyCo Grass+.

Illustrations: Tebbit Design

Photography: ADAS, BGS, EnviroSystems UK Ltd, NADIS

For more information contact:

Better Returns ProgrammeEBLEXAshton HouseAmbury Road SouthHuntingdonCambsPE29 3EH

Tel: 0870 241 8829Fax: 0844 774 6253Email: brp@eblex.org.uk

www.eblex.org.uk

EBLEX is a division of the Agriculture and Horticulture Development Board (AHDB).

© Agriculture and Horticulture Development Board 2011. All rights reserved.

EBLEX Better Returns Programme hasfunded the writing and publication ofthis booklet. While the authors haveworked on the best information availableto them, neither the Better ReturnsProgramme, nor the authors shall in anyevent be liable for any loss, damage orinjury howsoever suffered, directly orindirectly, in relation to the booklet orthe information on which it is based.

Reference herein to trade names andproprietary products and serviceswithout stating that they areprotected does not imply that theymay be regarded as unprotected andthus free for general use.

No endorsement of named productsor services is intended nor anycriticism implied of other alternativebut unnamed products.

1

Contents2 Growing good grass

4 Nutrients for silage

5 Big bales or clamp?

6 The ensiling process

8 Making good silage

10 Making good silage bales

11 Making good clamp silage

12 Silage analysis

14 Calculating winter feed rations

16 Making up a forageshortfall

17 Calculating the cost of silage

Grass grown for silage has different needs tograss grown solely for grazing. Done well, it canprovide high quality forage for winter feeding.

As with all crops, good silage depends on usingthe right varieties of grass, while optimisingsoil conditions for growth. Then manymanagement decisions are needed, includinghow to store, when to cut and how to feed.

Producing silage is not cheap. So the challengeis to produce enough of adequate quality forthe stock that is going to eat it, be it dry cowsor finishing cattle.

This manual covers many of the key issueswhen making silage.

Tables at the back can help you work outhow much silage you have, and to calculatehow much it costs to produce – which isuseful for comparing it to other potentially‘cheaper’ alternative feeds that may beavailable locally.

Dr Liz GeneverLivestock Scientist

EBLEX

Growing good grassThe starting point for growing good grass for silage is the soil. Having adequate fertility and good structure are crucial.

Less than 10% of beef and sheep farmers regularly soil test; and few dig holes to check what is happening under the surface. Without attention to the soil,grass and silage yields will be compromised.

BRP has produced a manual which takes a closer look at managing soils for best returns from grassland. Email brp@eblex.org.uk or call 0870 241 8829to request a free copy.

Selecting the right types of grassSilage can be cut from a variety of field types, from specialist short-term leys to permanent pasturesthat are mainly grazed.

Ryegrasses have been bred for many decades for yield, quality and the ability to utilise nutrients.They are important for silage making.

Both white and red clover can also make excellent conserved forage, but selecting the right type is essential.

Specialist silage Medium term cutting and Long term cutting andleys (1–3 years) grazing leys (2–4 years) grazing leys (5+ years)

Perennial ryegrass (diploid)

Perennial ryegrass (tetraploida)

Italian ryegrass

Hybridb ryegrass

White clover (small leaf)

White clover (medium leaf)

White clover (large leaf)

Red clover

�

�

�

�

�

�

�

�

�

� �

�

�

�

��

���

�

� �

� �

a Tetraploids have a more upright growth habit and work better in a cutting system.b Hybrid ryegrass is a cross between perennial and Italian varieties, combining the strengths of the two parent species.

2

The Recommended Grass and Clover Lists are updated annually providinginformation on the best performing grasses and clover available from merchantsparticipating in the Grass Levy Scheme. The varieties that make it onto the listhave been independently tested by NIAB.

Growth stagesAll grass wants to do is reproduce and throw up a seed head. Good grassland management preventsthis happening. With silage, the aim is to control the amount of heading.

Grass varieties have different heading dates which are triggered by different temperatures, eg earlyheading grasses can start to grow at low temperatures in March and April.

The stage of growth at which thecrop is cut will have more influenceon the eventual feeding value of thesilage, than any other factor underthe farmer’s control.

Heading dateGrasses are classified according to headingdate – the date on which 50% of the earsin fertile tillers have emerged. Choose asilage mixture with similar heading dates.

There is a tricky balance to achievebetween producing low yields of highlydigestible young grass, and high yields of mature stemmy herbage which has low digestibility.

The target will depend on the type ofstock being fed, eg dry cows or growingyoungstock.

Weed control High levels of perennial broad-leaved weeds such as docks and thistles reduce silage yield and quality.Weeds also use nutrients that have been applied to boost grass growth, wasting money.

Effective herbicides need up to three weeks to get into the roots. Plan spray dates and balance idealgrowth stage of the weed for treatment, with the anticipated cutting date.

Assess pasture in early spring and use a targeted product whenever possible. Ensure the weed is activelygrowing and follow manufacturers’ recommendations.

When considering whether to spray clover swards, assess the real density of clover, then compare thevalue of the nitrogen being supplied by the clover, with the cost of the yield reduction caused by theweeds. A 20% weed infestation will reduce grass yield by at least 20%.

72 D-value,leafy growth.

Typical first cut yield of a long

term ley – 4.6t DM/ha

68 D-value,lengthening

of stems.

Typical first cut yield of a long termley – 6.1t DM/ha

65 D-value, flower heads emerging.

Typical first cut yield of a long termley – 7.5t DM/ha

3

4

Nutrients for silageThe nutrient status of grassland can be boosted by inorganic fertilisers. However, the value of nutrientscontained in organic manures, which have been deposited by animals or spread mechanically, shouldbe taken into account before any inorganic fertiliser is applied.

14

12

10

8

6

4

2

0 Zero N 50kg N/ha/year

100kg N/ha/year

150kg N/ha/year

200kg N/ha/year

Acidity (pH)Yield reductions will result if pH falls below theideal of 6–6.5.

Phosphate (P) and Potash (K)Fields which are regularly cut for silage have ahigher requirement for P and K.

A 30% dry matter silage contains 2.1kg of P and 7.2kg of K per tonne of fresh material, so the addition of K is particularly important tomaintain grass yields.

Even at K index 2+, the maintenance requirement in a multi-cut silage system, is between40–60kg/ha at each cut. At index 2, on a grazing-only pasture, the maintenance requirement is nil.

Sulphur (S)Sulphur deficiency is increasingly common ingrassland, especially in second or later cuts wherehigh rates of nitrogen have been applied, andespecially on shallow or sandy soils. Deficienciescan cause large reductions in yield.

When S deficiency is indicated by poor growthand a yellow tinge to the youngest leaves, apply40kg of SO3/ha, as a sulphate-containing fertiliser,at the start of growth before each cut.

The 8th Edition of the Fertiliser Manual (RB209)goes into more detail and is available fromwww.defra.gov.uk

Nitrogen (N)Grassland can utilise 2.5kg N/ha/day (around 2units of N/acre/day) under ideal weather conditions.This can come from soil N, manures andinorganic fertiliser.

The average N fertiliser applied on UK beef andsheep farms is between 40–60kg/ha. Clover andmanure deposition increases the amount.

Too much N produces grass with low sugar levelsand any resulting silage can have high ammoniaand butyric acid levels, making it less palatable.Too little N compromises yield and protein levelscan be low.

Effect of nitrogen on grass yield

Clovers ability to ‘fix’ nitrogen and make itavailable in the soil for plants reduces theneed for additional fertilisers or manure ongrass/clover swards.

BRP has produced a manual that explains how red and white clovers can beincorporated into grassland systems.Email brp@eblex.org.uk or call0870 241 8829 to request a free copy.

pH <4.5 4.5–5.0 5.0–5.5 5.5–6.0 6.0–6.5

Yield 87% 88% 91% 96% 100%

Gra

ss y

ield

(to

nnes

DM

)

5

Pros Cons

Big Bales

Low aerobic spoilage Not suitable for very wet silage

Flexibility to cut at optimum cutting date for Labour intensive at feeding outeach field

Can target quality to livestock needs Risk of variability between bales

Good for storing surplus grass, especially cuts Prone to damage – mechanical, birds, vermintaken in autumn

Low dry matter loss (<5–10%) during Plastic disposal; high cost of compliance withproduction and storage waste regulations

Limited capital investment, low transport and High unit costs storage costs

Clamp

Large scale operation allows speedy harvest Depreciation cost of clamp

Consistent quality for each cut Higher DM losses than bale (25% vs 8%)

Suitable for a range of dry matters (up to 40%) Heating/mould development at face at feed out

Key: DM = dry matter

Big bales or clamp?The choice of storing silage as big bales or in a clamp will depend on the availability of a clamp andcontractors or equipment, the amount of silage being made and feeding system.

If managed well the quality of big bale silage can be similar to clamp silage.Fermentation losses are generally half of those reported in clamps.

TOP TIP: Record the yield (number of bales or number of loads) harvested off each field, andcalculate its total yield. This will highlight underperforming fields.

Silage making preserves grass in lactic acid produced by bacteria naturally present on the fresh crop.

These beneficial bacteria allow fermentation to take place which maintains nutrient content even aftermonths of storage. This process also prevents harmful bacteria and moulds developing.

WiltingAs soon as the crop is cut, the grass starts to losenutrients, due to plant respiration and the break-down of sugars and protein.

Rapid wilting and ensiling minimises these lossesby quickly creating acid levels that stop furtherrespiration. These reactions require anaerobic(air-free) conditions, which is why quickconsolidation in the clamp and sealing is crucial.

SugarFor best results the crop needs an adequate sugarcontent; 2–3% sugar in the fresh grass – equivalentto 10–15% sugar in the dry matter.

Young, leafy grass that has been well fertilised,grass/clover mixtures and autumn cuts, tend tohave low sugar levels, and lactic acid productionmay be insufficient to stop all spoilage. Applyingadditives can help prevent this.

Wet cropsWet crops have to reach a lower pH to inactivateall undesirable bacteria. Acid additives can helpachieve a stable preservation quicker.

Fermentation

Storage stage

Acidic conditions limit microbial activity aslong as clamp/bale is air tight

Micro-organism populations gradually decline

Potentially dangerous organisms such as clostridia and bacilli can survive as spores

Stable stage Can be reached in two to three days if additive used

Aim for pH 3.8–4.3

Fermentation stage Begins when no air left

Can last several weeks

Lactic acid dominates

pH drops to 3.7–5.0

6

The ensiling process

TOP TIP: To avoid soil contamination:• roll fields when ground conditions allow• carry out mole control in November • do not cut too low.

Acid based additives can help reduce theimpact of soil contamination.

Aerobic stage (air present) Lasts a few hours

Oxygen levels reduced

Well fermented silage has a fruity smell or no aroma and should look bright.

7

Problem Cause

Rancid, fishy odour. Slimy, sticky High butyric acid level due totexture • soil contamination or

• late manure application or • low DM (<30%)

Mouldy silage with a musty odour Presence of oxygen due to:• poor filling and sealing or• high DM ( >50%) or poor feeding-out management

Smells of vinegar Acetic acid (vinegar) fermentation due to high air levels

Sweet smelling silage High levels of ethanol produced by moulds plus some acetic acid

Ammonia odour Due to:• excessive protein breakdown to ammonia or • clostridial fermentation or • high pH

Smells like tobacco or burnt. Due to:Looks olive green. • excessive heating or

• too high DM

Key: DM = dry matter

ListeriosisListeria bacteria thrive in soil and can be pickedup at harvesting if the crop is cut too low or thereare a lot of mole hills in the field.

They are a particular problem of high dry matter,later cut silage which is more difficult to consolidateto exclude air.These forages often have low sugarcontent, leading to poor fermentation and a highpH.This allows the bacteria to multiply throughoutthe bale or clamp, even at low temperatures.

SheepAffected ewes havedrooping faces anddrool, and walk incircles as a result ofabscesses in the brain.Listeriosis also causes

abortions in pregnant ewes and presents a risk topregnant women.

Most cases occur four to six weeks after eatingaffected silage.

CattleSilage eye (Bovine iritis) in cattle can be causedby listeria infection from silage.

It can also causeabortions and circling. Healthy cattle are quiteresistant, but poor feed quality, cold, wet weather,and transport stress can increase the risk of infection.

BotulismSilage can become contaminated withClostridium botulinum toxins picked up from soil.If fermentation is poor the spores can survive,and can cause death.

The use of poultry litter as fertiliser on cattlepastures has also been identified as a risk factor.

What happens when it goes wrong?Poorly made silage has a noticeable, usually disagreeable smell. Animals will not be keen to eat it andthere will be a high degree of wastage. Some silages can be dangerous to feed.

8

Making good silageCutting dateCutting date has a significant impact on silage yield and quality. As the crop starts to bulk up andyield increases, quality starts to decline as the grass begins to produce stems and heads. These areless digestible than leafy growth.

Optimum cutting date should be influenced by the class of stock the silage will be fed to.

Targets for silage quality

Moisture contentReducing the moisture content of a crop by wiltingsaves carrying water and reduces effluent.

The target DM should be:

• 30% for clamp

• 35–45% for big bales.

NB: Excessive wilting causes poor fermentationand loss of nutritional value.

In the field:

• Mow after dew has dried off. Plant sugars are higher in the afternoon.A rapid wilt concentratesthe sugars allowing a quick and effectivefermentation

• A conditioner on the mower splits the grass, sothere is a greater surface area for water loss.Can increase wilting speed by up to 20%

• Leave a stubble of at least 5cm

• Spread the crop quickly and over a wide area.Water loss is highest for the first two hoursafter cutting

• Ensure rakes and tedders are set at the right height so they work efficiently and do not pickup soil or manure

• Wilt as rapidly as possible for a maximum of 48 hours

• Row up into even ‘box-shaped’ swaths immediately before pick-up or baling.

As a rule, D-value falls by 0.5 units a day from when the grass starts to push up flowering stems.

Good Moderate PoorD-value 70 65 60

% of ear emergence 25% 50% 100%

Energy ME (MJ/kg DM) 11.5 10.5 9.5

Crude protein content 16 12 10(%)

Ammonia N as proportion 50 100 150of total N (g/kg)

% DM (clamp silage) 28–30 25 20

Feed to: Finishing stock, ewes Growing cattle, autumn Dry stock, spring carrying multiples calving suckler cows, calving suckler cows

ewes carrying singles

Key: D-value = measure of feed digestibility.

9

Additives

Additives cannot make a bad grass crop into good silage. When used well on goodgrass, they can improve fermentation and animal performance.

Additives are generally applied as the grass is being picked-up or baled, via a specific applicator.Different products vary in what they do, so it is vital that the right one is selected.

Chop length Chopping grass when it’s being picked-up or baledcan lead to more efficient silage fermentationthrough greater release of sugars.

Chopped material is easier to consolidate in aclamp and leads to denser bales (8–12% heavierthan un-chopped).

Chopped silage also breaks down more rapidly inthe rumen leading to higher animal intakes and

performance. But too short a chop length can leadto poor rumen health.

Use different chop lengths for silages of differentdry matters:

Crops that contain red clover needto be treated slightly differently.

• cut when in mid-bloom

• leave a stubble of 7–8cm

• do not use a conditioner

• leave in wide swaths and do not ted, to reduce leaf shatter

• wilt for a maximum of 48–72 hours

• chop the crop

• use an inoculant.

DM of silage Ideal chop length 28–35% 2.5–5cm

20–28% 8cm

<20% 8–10cm

Type How they work When to use itBacterial inoculants Bacteria convert grass sugar for bacteria to All crops, especially high

convert to lactic acid DM, late or leafy cuts

Enzymes Convert fibre in grass into sugars that bacteria Crops low in sugarcan convert to lactic acid. May decrease stability when being fed out

Non protein nitrogen Ammonia and urea are added to improve Low protein silagessources protein level and improve stability when being

fed out. Can be hazardous

Acid, eg formic Rapid fall in pH. Can be hazardous and reduce Low DM silages, cropspalatability of silage low in sugar

Sugar supplements, May increase amount of sugar for the lactic Crops low in sugareg molasses acid bacteria to convert. High rates and equal

distribution needed

Always evaluate the use of an additive before buying, based on its potential effect onthe forage and livestock performance, as well as the cost.Always follow manufacturer’s application instructions.

10

Making good silage balesSilage destined for bales can be wilted to 35%–45% DM. Drier crops arelighter, but are more prone to moulds and less efficiently used by livestock.Bales can be round or rectangular. Fermentation may be better in rectangular bales as they are denser.They are also easier to transport, but need heavy duty handling equipment due to their weight andare prone to damaged corners.

Baling• Ensure baler is well maintained

• Aim for dense, well-shaped bales to produce heavier but fewer bales per hectare, reducing baling and wrapping costs

• For a round baler, clean the rollers regularly to avoid build-up of material

• Use net wrap to speed up baling

• To prevent soil contamination, check ground conditionsand adjust stubble height to minimise risk.

Wrapping• Ensure wrapper is well maintained

• Wrap within two to three hours of baling, preferably atthe store site. Remove field-wrapped bales to the storagearea without delay to avoid damage from birds

• Use high quality film with 55–70% pre-stretching.Whenthe wrap is applied it will shrink creating a good seal

• Use six layers of wrap – counted on the sides of the bale

• Consider green or white wrap to reduce heat at bale surface, as heating can affect fermentation and cause spoilage

• Handle and store to avoid damage to wrap.

Stacking• Ensure site is level and winter access is possible

• Follow HSE guidance on stacking bales

• <25% DM one bale high

• 25–35% DM two bales high

• >35% DM three bales high

• Bales within the stack retain their quality better than bales on the outside, so place the best silage within the stack

• Stack more than 10m away from watercourse

• Net and bait stack to prevent bird and rodent damage.

11

Preparing the clamp• Remove any old, mouldy or rotting silage and

clean thoroughly

• Having airtight silo walls is very important – use a side sheet

• Check there is adequate effluent drainage at floor level.

Clamp filling• Fill the clamp rapidly, spread silage evenly and

consolidate well.

The pressure exerted under the wheels ofa heavy tractor will only be effective for upto 20cm depth.

• If silaging continues the next day, sheet down overnight

• DO NOT ROLL the following morning as thiscreates a vacuum and pulls more air into thesilage when the aim is to get all the air out

• Prevent soil contamination by cleaning tractortyres before rolling. Keep tipping area clear of mud.

Clamp sealing• Seal as soon as consolidation is complete

• Cover with two sheets of plastic – a thinnersheet first and a thicker protective sheetabove. Or a new sheet covered by last year’sold sheet

• Place tyres or bales on top. Ensure all tyrestouch each other

• Ensure the sheet is not punctured. Protectfrom birds with netting

• Ensure that unroofed clamps shed rainwaterevenly and freely and that it does not seepinto the clamp.

Managing silage effluent• Effluent must be collected as it is highly polluting

• Most effluent will be produced in the first tendays after ensiling. Short chop lengths increaseearly peak flow, as do acid-based additives

• Clamps should have an effluent storage capacityof at least two days at peak flow

• Collected effluent can be spread on to land butshould be diluted 1:1 with water to reduce therisk of pollution and sward scorch. Aim for arate of between 25–30 m3/ha (2,200–2,700litres/acre). Do not spread near watercoursesor bore holes

• In Nitrate Vulnerable Zones, silage effluent hasto be treated as an organic manure, so closedperiods must be adhered to.

Making good clamp silage

DM % Amount of effluent releasedof crop25 Little

18 100 litres/tonne/day at peak flow

15 200 litres/tonne/day at peak flow

12

Silage analysisBefore planning winter rations find out how good or bad your forage is, as this will form the largestcomponent of the winter diet.

Detailed silage analyses can be carried out by independent or feed company laboratories. Some basicindications of silage quality can be done on farm.

On-farm testing• Dry Matter (DM)

The dry matter of conserved forages of less than 30% can be estimated by squeezing a handful of silage.

The dry matter in drier chopped silages can be estimated by taking a handful of silage and compressingit tightly for half a minute, before suddenly releasing and noting the effect on the silage ‘ball’.

• Energy (ME) and Protein Content (CP)

In ryegrass-based swards, these can be estimated by looking at the leaf and stem content.

• Acidity (pH)

All silages can be measured with pH (litmus) paper. Put 10g of silage in 90ml of water in a polythenebag. Mash gently by hand for two minutes before dipping litmus paper into the liquid. Portable pHmeters can also be used.

Amount of squeezing DM %

Juice easily expressed by hand <20

Juice expressed with some difficulty 20–25

Little or no juice expressed but hands moist >25

‘Ball’ shape DM %

Ball retains its shape and some free juice expressed <25

Ball retains its shape but no free juice is expressed 25–30

Ball slowly falls apart 30–40

Ball rapidly falls apart >40

Leaf and stem content ME (MJ/kg DM) CP (%)

Very leafy – no stem visible 12 18

Leafy – some stem present 11 16

Leafy with some flowering stems 10 14

Moderately leafy with large numbers of flowering stems 9 12

Stemmy – grasses at flowering stage 8 10

Stemmy – grasses at post flowering stage 7 8

13

Understanding forage analysis

Dry Matter (DM%) – a measure of what is‘not’ water.

If silage is too wet (less than 25% DM), it can bedifficult for animals to eat enough to meet theirneeds. If this is the case, more concentrate feedmay be required to meet nutritional requirements.

Clamp silage

Bale silage

D-value – a measure of feed digestibility

The higher the D-value the less concentrates willbe needed to balance a ration.

Energy (ME MJ/kg DM) – a measure of the usableenergy available to the animal when fed.

When buying a supplement, make sure the ME ishigher than that of the forage.

Crude Protein (CP%) – a measure of theprotein content (but not of protein quality.)

It is important to provide enough protein insupplementary feeds to make up any shortfall inthe forage.

pH – a measure of acidity

Low levels indicate a stable fermentation, but veryacid silage (below pH 4.0) can affect palatabilityand restrict how much an animal eats.

Ash% – a measure of mineral and traceelement content

Levels over 10% indicate soil contamination and poor fermentation and should not be fed.

High ash figures for legume silages is normal due to their high mineral content.

GOOD POOR>25% <22%

GOOD POOR>14% <10%

GOOD POOR4 <3 or >5

GOOD POOR70 58

GOOD POOR11 <10

GOOD POOR>30% <22%

Taking silage samplesIt is important to take a sample that represents thewhole clamp or all bales, and to sample differentcuts and fields separately.

1. Wait six weeks after harvest.

2. Take several cores across the clamp at least 1.5metres deep, or from at least five bales of thesame batch.

3. Send to lab early in the week.

4. Pack into a polythene bag and squeeze air out before sealing tightly.

5. Give the lab as much information as possible eg grass only, red clover, 1st or 2nd cut, bale or clamp,if an additive was used.

There are two types of analysis:

• Wet chemistry is the traditional method of analysing forages and uses lab techniques toanalyse the sample.

• NIRS (Near Infrared Reflectance Spectroscopy) uses how light is absorbed and reflected back toanalyse the components of a sample.

NIRS has been calibrated back to wet chemistry,but care needs to be taken if the forage sample isnovel, eg brassicas or chicory. If the clover percentageis greater than 30%, the calibration curves may notbe robust enough.

14

A B C D E F G

Clamp details (m) Capacity Density Tonnes Tonnes Silage type (m3) (see (fresh DM% (DM)

AxBxC below) weight) FxG/100Length Width Height DxE/1000

Eg 1st cut grass 30m 10m 3.5m 1050 615 646 30 194

DM%Grass Silage Maize Silage Wholecrop Silage

kg Fresh Weight/m3

20 725

25 660 650

30 615 620

35 600 600 605

40 590

45 585

55 565

Silage density

NB: Density will also depend on chop length, consolidation and depth of silage.

How many tonnes of silage in round bales?

As a guide: 4ft wide round bales = 0.5 tonnes fresh weight. 5ft wide round bales = 0.63 tonnes fresh weight.

How many tonnes of silage are in the field?

A B C

Silage type No. of bales Bale weight (t) DM % Tonnes (DM)AxBxC/100

Eg 2nd cut grass 400 0.63 30 76

A B CSilage type Crop area Expected harvested DM % Tonnes (DM)

(hectares) fresh yield (tonnes/ha) AxBxC/100

Eg 1st cut grass 20 20 25 100

Calculating winter feed rationsWork out how much forage is available.Then estimate how much is needed to see the animals throughthe winter. Fresh weights do not reflect the amount of nutrients in feeds, so focus on dry matterrequirements and availability. Use the following examples to calculate how much silage you have orneed to buy in.

Work out how much silage there is

How big is the clamp?

15

Silage requirement

Now calculate stock requirements The dry matter intake of stock can be estimated as a proportion of their liveweight using the tables below.

Stock intakes

Stock DM Intake (proportion of liveweight)Rearing cattle 0.023

Finishing cattle 0.02

Suckler cows 0.02

Cull cows 0.02

Ewes 0.017

Lactating ewes 0.025

Lambs 0.02

Tonnes (DM)Clamp silage 194

Round bale silage 76

Crops in field 100

TOTAL 370

A B C D EType of Number Average DMI Daily Feeding Total tonnesstock liveweight (see above) requirements period required (DM)

(kg) (kg) AxBxC (days) DxE/1000

Ewes 600 70 0.017 714 100 71.4

Suckler cows 80 600 0.02 960 150 144

Rearing cattle 75 300 0.023 517.5 150 77.6

Finishing cattle 75 500 0.02 750 100 75

Total DM to be eaten (tonnes) 368.0

Safety margin – allow for losses, e.g 5–10% 36.8

Total tonnes of DM required 404.8

Total amount of forage available in this example

Work out the differenceFinally deduct the DM required from the DMavailable to give the overall surplus or shortfall.

Tonnes (DM)Total DM available 370.0

Total DM required 404.8

Surplus or shortfall -34.8

16

� If planning early enough, sow a brassica crop.

� Reduce stock numbers or out-winter some stock.

� Find alternative forage sources eg standing maize or buy-in moist feeds.

� Consider straw and concentrates or liquid feedseg pot ale syrup.

� Plant a grass catch crop to allow early spring turnout.

� Reduce waste.

� Check weigh scales on mixer/feeder wagons are accurate.

Buying in additional feedsFeed cost per tonne has a big effect on feed costs.Remember to work out the cost/tonne of drymatter when comparing the value of one or morepotential feeds.

Reduce the cost of bought-in feeds by taking fullloads. Locate local sources of alternative feeds tokeep transport costs down. Collect quotes from anumber of suppliers.

Reducing avoidable losses Dry matter and feed value can be lost at everystage of silage making.

Where losses occur

In the field at harvest 2–12%

In the clamp (from respiration/ 5–18%fermentation)

In effluent 0–8%

Feeding out (from exposure to air) 1–10%

Exposure to air causes spoilage because yeastsdestroy the preserving acids so the pH rises andheat is generated. Moulds grow which can produceharmful mycotoxins.

Feeding out from a clampMinimise the amount of air that reaches exposed silage.

� Expose only the silage needed each day.

� Use narrow clamps. Aim to get across theface in three to seven days.

� Use a shear grab and sharpen regularly.

� If using big bales make sure each one is consumed ideally within two days of unwrapping.

Managing feedingSilage can be wasted inthe feeding area due tocompetition and fightingby the animals. Ensurethere are enough feedingspaces for all animals to eat at once, or anincreasing proportion will be wasted.

Feeders that make animals eat with their headsdown can reduce waste, as can slanted barbarriers and feeders with solid bottoms.

Find a way to remove rejected silage effectivelybefore putting out more.

Making up a forage shortfall

17

Calculating the cost of silageKnowing how much it costs to grow, make and feed silage allows farmers to make decisions about futurefeeding – ie whether cheaper alternatives can be bought-in or whether different crops should be grown.

Step 1: Work out costs on an area basis

Rental value – everything grown on a farm carriesa rental value – if a silage crop was not grown, theland could be let.

£250/ha/year* is a standard figure. 1st cut normallyproduces 40% of the total annual yield.

Establishment and grassland management – re-seeding costs average £250/ha – so for a five-yearley £50/year. Allocate 40% to 1st cut silage. Includeweed control expenses on the same basis.

Inputs – limited on grassland but with crops likemaize, include sprays and plastic etc.

Machinery – most contractor operations are easyto allocate on an area basis. The calculations canget more complicated when the farm makes its ownsilage. It is simpler to use contractor prices orpublished figures as a start point.

Other costs – eg additives, sheeting, analysis.Theseare probably recorded on a per clamp basis. Simplydivide the total by the area going into the clamp.

* Full reseed, including ploughing = £375/ha.Overseeding = £175/ha.

Example (40 ha, 1st cut, 68 D, clamped)

Costs per ha

£250 x 40% = £100

Re-seeding costs = £20

Fertiliser400 kg of 20:10:10= £270 x 40% = £108

Slurry application = £25

Rolling = £21

Fertiliser spreading = £6

Mowing = £17

Tedding/rowing = £15

Carting/clamping = £107

Additive = £800/40 ha = £20

Sheet and analysis cost= £120/40 ha = £3

TOTAL per ha = £441

Forage quality is key to animal performance. Reducing forage costs by growing bulky,low D-value crops is a false economy.

NB: Some fixed costs should also be allocated, eg the cost of the clamp.

Step 2: Use the calculations on pages 14 and 15 to calculate the yield

Step 3: Work out costs – pence per kilogram of dry matter (p/kg DM)

Divide the total area costs by the estimated yield:

£441/20 tonnes fresh weight (FW) = £22.05 per tonne of FW = 2.205p per kg FW

To convert costs of FW into DM variable costs = cost per kg FW x (100/DM%)So @ 25% DM = 2.205 x (100/25)= 8.8p per kg DM

To compare the cost of silage to other feeds available to buy, convert the costs of a kg DM into p/MJ of ME So @ 11 MJ of ME per kg DM = 8.89 /11 = 0.80p per MJ of ME

For more information contact:Better Returns Programme

EBLEXAshton House

Ambury Road SouthHuntingdon

CambsPE29 3EH

Tel: 0870 241 8829Fax: 0844 774 6253

Email: brp@eblex.org.ukwww.eblex.org.uk

© Agriculture and Horticulture Development Board 2011.

All rights reserved.

The tables and contents of this publication may not bereproduced without the express permission of EBLEX.

Other BRP publications available

Beef BRPManual 1 – Choosing Bulls to Breed for Better ReturnsManual 2 – Beef Selection and Handling for Better ReturnsManual 3 – Improving Cattle Handling for Better ReturnsManual 4 – Beef Production from the Dairy HerdManual 5 – Feeding Suckler Cows and Calves for Better ReturnsManual 6 – Improve Beef Housing for Better ReturnsManual 7 – Feeding Growing and Finishing Cattle for Better ReturnsManual 8 – Optimising Suckler Herd Fertility for Better ReturnsManual 9 – Controlling Worms and Liver Fluke in Cattle for Better Returns

Sheep BRPManual 1 – Target Lamb Selection for Better ReturnsManual 2 – Target Ram Selection for Better ReturnsManual 3 – Target Lamb Management for Better ReturnsManual 4 – Target Ewe Management for Better ReturnsManual 5 – Target Store Lamb Management for Better ReturnsManual 6 – Target Easier Management for Better ReturnsManual 7 – Target Lameness for Better ReturnsManual 8 – Target Worm Control for Better ReturnsManual 9 – Improving Ewe Breeding for Better ReturnsManual 10 – Controlling External Parasites for Better ReturnsManual 11 – Target Ewe Fertility for Better ReturnsManual 12 – Improving Ewe Nutrition for Better ReturnsManual 13 – Improving Sheep Handling for Better Returns

Joint Beef and Sheep BRPManual 1 – Improving Pasture for Better ReturnsManual 2 – Improved Costings for Better Returns Manual 3 – Improving Soils for Better ReturnsManual 4 – Managing Clover for Better ReturnsManual 5 – Making Grass Silage for Better Returns