Fact Sheet November Why Analyse Silage?

Transcription

1 Fact Sheet November 2012 Why Analyse Silage?

2 Mileage in Silage Why analyse silage? Tips for sampling silage Winter performance and costs for housed livestock are driven by the quality of silage fed. Knowing silage quality will help you to: Optimise animal performance and profitability Feed all classes of stock correctly Plan winter feeding and calculate if forage stocks will last the winter Maximise forage contribution and minimise concentrate input where stocks are plentiful Buy the right concentrates and supplements Give advance warning of any problems ; - spoilage/wastage - intakes - energy/protein deficits Always aim to balance silage with concentrates, not the other way round. The results are only as good as the sample - make sure samples represent what you will feed and sample each cut or field separately. 1. Sample a minimum of six weeks after harvest, to ensure fermentation has finished. 2. Provide the analytical services with as much information as possible. (e.g. crop type grass, red clover/grass, mixed sward. 1st, 2nd or 3rd cut. Bale or clamp. Additive used). 3. Keep the corer sharp - a blunt corer will squeeze the moisture out of a sample and mean the dry matter analysis will be less accurate. 4. Mix the core samples on a clean surface and then halve, repeat if necessary. 5. Place a 0.5kg sub sample into a clean polythene bag. 6. Squeeze air out of bag before sealing. Clamp silage Take three full depth core samples from the top of the clamp along the diagonal of the clamp. Big bale silage Take a full depth sample through a number of bales and mix and split as for clamp samples. Consider variability and sample batches that are likely to be similar. Take separate samples where ley type, cutting date and maturity differ

3 Which analysis? DIY silage assessment NIRS (Near Infrared Reflectance Spectroscopy) A fast, accurate and relatively cheap method of analysing grass silages developed by calibrating results from those of wet chemistry. Wet chemistry More expensive than NIRS but can be more accurate, it involves analysing forages using laboratory techniques. This method is most suitable for novel forages such as red clover or whole crop. Use the guide below to quickly assess your silage. What you see and smell, combined with a laboratory analysis helps estimate the amount and quality of silage. Dry Matter (DM) Estimate silage DM content for silages with DM less than 300g/kg by squeezing a handful of silage: Squeezing pressure Dry Matter (%) Juice runs easily through hands Below 20% Squeeze hard to get juice 20-25% Little or no juice but hands moist Above 25% For drier chopped silage take a handful of silage and squeeze into ball for 30 seconds before suddenly opening hands and watch the effect on the silage ball : Metabolisable Energy (ME) and protein Look at leaf and stem content. Leaf & stem Very leafy - no stems Leafy - some stems Leafy with some flowering stems Moderately leafy with large numbers of flowering stems ME (MJ/kgDM) CP (%) 9 12 Stemmy grasses at about flowering 8 10 Stemmy grasses at post flowering 7 8 ph The acidity of silage affects intake and stability (see page 5). Measure with ph (litmus) paper or a portable ph meter. Ball shape Dry Matter (%) Ball keeps its shape and some juice Below 25% Ball keeps shape, no juice 25-30% Ball slowly falls apart 30-40% Ball rapidly falls apart Above 40%

4 What does the smell tell you about fermentation? What does laboratory analysis of silage tell you? Fermentation Smell Why? / Causes See below for key terms, values and how results affect feed-out. Good no strong smell, lactic acid fermentation Oxygen kept out Quick fermentation of sugars Good cutting, carting and ensiling Target Range How result affects feed-out (Butyric) (Ammonia) (Acetic) strong, offensive, sometimes fishy ammonia vinegar Soil contamination: cutting or raking too close to the ground, soil from rolling tractor tyres splash from rain manure applied too late Dry matter below 30% and low sugar level With clostridial fermentation silages often have low feed value High ammonia caused by protein breakdown, slow ph drop or clostridial fermentation Wet and poorly compacted silages tend to have high ammonia Extremely wet silages (below 25% DM) Slow fermentation (due to high buffering capacity) Loose packing Slow silo filling All affect acetic acid levels and increase losses Dry Matter (DM) % D Value (D) % Metabolisable Energy MJ/kg DM (ME) Crude Protein (CP) % Clamp Bales Above 68 Productive stock Above 10.8 Productive stock Too wet or too dry - reduces intake and increases supplements required for productive stock Too dry - risks of puncture to wrap/sheets and deterioration High D Value Minimises feed need - but take care if only maintenance level feeding required. Linked to digestibility (see above). Energy must be balanced to meet livestock performance targets and reduce protein losses to the environment. Balance the protein in the diet with energy for optimum performance and minimal Carbon footprint. ( Ethanol ) Overheated sweet smelling caramel/tobacco Indicates yeasts, high losses and risks secondary fermentation when exposed to air May taint milk Very dry silage Reasonable intake but low animal performance Ash % Below Ash levels above 10% may indicate the presence of soil. This will increase the risk of listeriosis and clostridial diseases, especially in in-lamb ewes and silage eye in cattle. Listeriosis is a health risk to pregnant women. Mould Results from poor packing, slow filling, dry conditions, slow feed-out and poor face/wrap management

5 Fermentation: how well is it made? Have you got enough silage? Target ph Range Depends on DM Higher ph acceptable at higher dry matter, e.g. in Bales. (see 2 nd table below for guidance) It is important to work out how much silage you ve got and how much your livestock will eat. Looking at the volume or number of bales is not enough because dry matter and density vary from year to year and cut to cut. The tonnage of silage should always be calculated on a dry matter basis to take this into account. Ammonia N as % TN Total Fermentation Acids %* (TFA) Below Above 10 (Depends on DM) 2-20 The best indicator of silage fermentation. Below 5% is excellent fermentation, a stable silage and minimal nutrient loss. Above 15% is poor fermentation. Extent of fermentation. Lower in dry silages with restricted fermentation. How much silage have you got? Volatile fatty acids (VFA) % Below 2% of TFA 1-9 High levels indicate poor fermentation. Clamp Step 1: Calculate the volume of silage Volume of silage (m 3 ) length(m) x width(m) x height(m) Lactic Acid %* Butyric %* Below Intake Potential Above DM range (g/kg) < Lactic acid is the good acid in silage. In a well fermented silage, lactic acid should comprise at least 75% of the TFAs. Butyric acid indicates poor fermentation typical of anaerobic conditions, high soil contamination, slow rate of fermentation, low DM and secondary fermentation. Combines the feed value and fermentation characteristics to give a guide to how well it will feed. * Good quality silages with low acetic, ammonia-n, butyric and with high lactic and sugars are prone to aerobic spoilage. These need to be managed correctly to avoid losses during feed-out >30 Step 2: Look up the density from dry matter % and ensiled clamp height table Silage Dry Matter (%) Silage Density (tonnes/m 3 )* Ensiled Height (m) Source: Silage Density (DairyCo Feeding Plus) *Density varies with chop length, consolidation and moisture (DM %) ph needed Step 3: Calculate the amount of silage (tonnes of dry matter) Tonnes (dry matter) Volume (m 3 ) x Density (t/m 3 ) x DM (%) 100 A

6 How much silage have you got? How much silage do your stock need? Bales Step 1: Weigh a representative number of bales and record average weight in tonnes (t) Step 1: Calculate how much each will eat each day: daily intake; kg dry matter (kg DM) - put units in formula. Animal daily intake (kg DM) Weight of livestock x predicted dry matter intake* Step 2: Count bales 100 Step 3: Calculate the weight of silage in bales (tonnes of dry matter) Tonnes (dry matter) number of bales x weight of bales(t) x DM% 100 B *As a rule of thumb average dry matter intake (kg) is around 2.3% of liveweight for beef and sheep and 3% for dairy cattle. Your nutritionist can give more accurate information based on stage of lactation/growth and predicated intake. Step 2: Work out how much each group of stock will eat over the winter. No of stock x daily intake (kg DM) x days fed total silage intake (kg DM) Step 4: Add up the total weight of silage in clamp and bales (tonnes of dry matter) Total weight of silage (t DM) A + B C Step 3: Add up the total for each group to know the amount of silage your stock will eat. Livestock need kg DM Group 1 + kg DM Group 2 + kg DM Group 3 etc 1000 D Step 4: Allow for waste and spoilage. Take the total amount the stock will eat for waste and spoilage. D and add 10% to allow E Step 5: Is there enough? E Subtract silage needed ( ) from silage available ( ) to give surplus or shortfall. C

7 Next steps Contact Have your silage analysed. Use the results; - think about what you will change next year to make better silage. - take advice; an independent nutritionist can provide information on the feeds available on the market, current prices and the best combination of feeds for each class of stock. - decide what action you will take if you have a shortfall or surplus of silage. Control spoilage and waste over the winter. Ensure the sheet/wrap keeps air out all winter; - Clamp: keep sheet close to the cutting face of the silage, use a sheer grab to keep the face tidy and reduce entry of air. - Bales: Net bales, repair any holes in wrap and control vermin. Monitor livestock performance and modify rations as necessary. Midway through the winter check that you have enough silage to last and revise rations. Purchase fodder/additional feed as necessary. Authors: Heather McCalman,,Sue Buckingham, Huw Powell GDC, IBERS For more information on Farming Connect services and events, contact us: Phone farmingconnect@ menterabusnes.co.uk website /farmingconnect Catch up with all the latest news from Farming Connect by joining our online community. Follow us on: Facebook facebook.com/farmingconnect Farming Connect support, guidance and training is delivered by Menter a Busnes on behalf of the Welsh Government 11