Attention to Detail Needed to get Best from Grass Silage


The latest results from Trouw Nutrition GB confirm the early indications for the prospects from first cut grass silages and provide new information on second cuts and wholecrop. They highlight that considerable variability means forages will need careful monitoring to optimise performance.


The Trouw Nutrition GB analytical laboratory, the largest testing facility in the UK, has now tested over 2100 first cuts and 1170 second cuts, making the data sample the most significant and robust available to farmers and nutritionists. “The results confirm the impact of the extended and inconsistent


harvest season for first cuts which has had knock-on effects for second cuts,” Dr Liz Homer explains. “The variable quality within and between clamps is going to present some practical challenges but farmers who analyse clamps regularly will be best placed to make the most of forages this winter.” While there are some very good quality first cuts, the overall


picture is of silages with low crude protein content and high NDF levels. These will have consequences for the supply of rumen energy, the choice of protein supplementation and on rumen flow and intakes. The average first cut is 33.6% dry matter, 11.3MJME/kgDM,


12.9% crude protein and 44.5% NDF. For second cuts analysed so far the average dry matter is 35.5% with 10.9MJME/kgDM, 13.5% crude protein and 45.7% NDF. However, Dr Homer emphasises that there is a considerable range between crops and while the averages give a good overall picture, it is vital farmers analyse their own clamps regularly. “Looking behind the headline figures, the analyses indicate that


the rumen will need careful balancing with fermentable carbohydrates and protein. Rumen fermentable protein will be needed to balance the rumen but bypass protein will also be important. “It will also be important to keep a close check on acid load and fibre index to maintain good rumen health.” Dr Homer says early wholecrop analyses suggest good dry matter content and starch levels with slightly higher energy overall. She stresses there is no doubt that rations will need careful fine-


tuning this winter to ensure the rumen is balanced and to take account of variations in silage quality between cuts. She recommends farmers to take a proactive approach and increase the frequency of analysis so they have a sound foundation for ration formulation and the choice of supplements to optimise income over feed costs. “Don’t wait for the rep to call or for cow performance to drop


before taking a silage sample. For a 250 cow herd we would recommend sampling clamps approximately every three weeks. Taking a representative sample can be done in the time it takes the mixer wagon to mix a diet so time should not be an issue. As results


PAGE 50 SEPTEMBER/OCTOBER 2021 FEED COMPOUNDER


are typically back in 24 hours you will be well placed to decide on what changes to make, if any. “Then watch how the cows take to the diet, paying close attention


to manure consistency, feed refusals and signs of sorting. By paying close attention to detail it should be possible to make the best use of this year’s forages,” she comments.


Average 2021 first and second cut grass silage and early wholecrop analyses (source: TNGB)


First cut average


Number of samples


Dry matter (%)


Crude protein (%DM)


D value (%)


ME (MJ/kgDM) NDF (%DM)


Starch (%DM) Acid load


Fibre index


Dynamic Energy (MJ/kgDM)


NDIP (g/kgDM) Rapidly


fermentable carbohydrates (g/kgDM) Total


Fermentable Carbohydrates (g/kgDM) Rapidly


Fermentable Protein (g/kgDM) Total


Fermentable Protein (g/kgDM) NFEPB (g/kgDM)


2125 33.6 12.9


70.9 11.3 44.5


49.5 178.6 5.99 59.3 210.4


Second cut average


1173 35.3 13.5


68.1 10.9 45.7


47.5 183.7 5.95 60.0 197.4


Wholecrop average


447 40.9 8.5


66.7 10.4 41.4 28.1 47.4


174.4 5.57 41.7 211.3


450.3


444.5


424.0


81.3


83.0


49.4


93.9 -1.53


96.6 2.35


55.5 -26.4


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