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Reporting on the results of more than 1,000 samples analysed at the company's laboratory in Ashbourne, Nacia Bonnick from Trouw Nutrition says the results show a familiar pattern to 2024 in terms of dry matter, energy, and protein.

However, closer inspection reveals important changes in nutrient availability that will require fine-tuning to ensure optimal rumen efficiency and milk production.

Ms Bonnick says: "The winter weather has again significantly affected first cut silages.

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"Overall farmers saw higher than usual grass growth throughout the winter due to warmer temperatures, especially in February. This strong growth resulted in more mature grass being cut. However, many farmers took advantage of the dry, warm harvest window in late April and early May which may have reduced the impact on quality."

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Ms Bonnick says the headline figures are similar to 2024 with 33.2% dry matter, down 0.5%. ME content has declined slightly to 10.86MJ/kg DM while crude protein dropped from 14.4% to 14.1%. NDF levels have increased from 46.6% to 47.7%, but the increase would have been greater had farmers not taken crops earlier.

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"At first glance the silages appear reasonably consistent year on year, but the small differences will add up.

"For a herd feeding 12kg grass silage dry matter per day, the reduced ME will drop production from M+9.4 litres to M+9.1 litres, equivalent to 60 fewer litres per day for a 200-cow herd. That is before factoring in the rumen impact of the reduced fermentability.

"Diets will need additional supplementation to maintain production and the analysis indicates some fine tuning will be required by nutritionists as the season unfolds to support margins."

Ms Bonnick says the results show a shift in the fermentability of carbohydrates and proteins. While Total Fermentable Carbohydrates (TFC) have increased marginally, the proportion of Rapidly Fermentable Carbohydrates (RFC), the fraction most readily available for rumen microbes, has decreased.

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This shift means that although cows may be consuming similar total carbohydrate levels, the speed and efficiency of energy release in the rumen is reduced. As a result, nutritionists will need to consider introducing more RFC sources such as cereals or molasses to restore the synchrony between energy and nitrogen release in the rumen.

Levels

Meanwhile, both total and rapidly fermentable protein levels are down, which may limit rumen microbial activity and impact fresh cow performance unless diets are properly adjusted.

Diets may require targeted supplementation with rumen-degradable protein (RDP) sources like urea-treated grains or specific protein blends, as well as rumen-protected amino acids for improved post-ruminal absorption.

To address these marginal shifts in nutrient availability, RFC will need to be synchronised with RDP to support microbial efficiency.

This may involve including fast-release starch sources such as rolled wheat or maize meal, alongside degradable protein feeds. Where protein supply is limited, bypass protein or rumen-protected amino acids can help meet the needs of high-yielding cows.

DigestibilityÌý

Higher fibre levels also demand strategies to improve digestibility, such as using yeast or buffer additives. Regular silage analysis will be essential to track changes in dry matter and fermentation quality, allowing timely adjustments. Fresh cows, in particular, will require focused nutritional support to ensure sufficient energy and protein supply during this vulnerable period.

Ms Bonnick adds that while the first cut results are somewhat disappointing, there is room for optimism. Early cutting has allowed grass to recover quickly, aided by warm weather and rainfall, potentially setting up a stronger second cut. However, she cautions that precision feeding will be vital going forward.

"There is no room to rely on averages this year. Get clamps analysed frequently and work closely with your nutritionist to adjust diets accordingly."

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Initial first cut grass analysis 2024 and 2025 (Source: TNGB)

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