The first maize silage analysis results for 2025, based on over 1,600 samples, clearly show the impact of the atypical growing season and the need for attention to detail when formulating diets, says forage analyst Trouw Nutrition GB.
The 2025 growing season saw a warm, dry spring across much of the UK, allowing early drilling into good seed beds and rapid establishment. But the prolonged period of high summer temperatures and low rainfall led to low soil moisture, with an impact on growth and development. In turn, this led to inconsistent cob development and crop maturity.
“While the overall consequence is more variable maize crops this winter, the test results suggest that farmers can be encouraged by the prospects for feeding maize,” comments Trouw Nutrition GB ruminant nutritionist Isabelle England. “That said, it will be vital to understand the analysis of the maize being fed, making regular analysis crucial.”
| 2024 | 2025 | ||
|---|---|---|---|
| Dry Matter | % | 30.7 | 29.9 |
| Crude Protein | % DM | 7.9 | 8.3 |
| D Value | % | 70.9 | 70.5 |
| ME | MJ/kg DM | 11.1 | 11.1 |
| Starch | % DM | 28.4 | 26.2 |
| Starch Degradability | % | 80.8 | 76.8 |
| Bypass Starch | g/kg DM | 53.5 | 60.3 |
| NDF | % DM | 42.1 | 43.5 |
| ADF | % DM | 26.1 | 25.7 |
| Lignin | g/kg DM | 34.2 | 30.2 |
| Ash | % DM | 3.5 | 3.7 |
| Lactic Acid | g/kg DM | 45.7 | 58.5 |
| pH | 3.9 | 3.8 | |
| Rapidly Fermentable Carbohydrate | g/kg DM | 209.7 | 193.7 |
| Totally Fermentable Carbohydrate | g/kg DM | 504.7 | 510.7 |
| Rapidly Fermentable Protein | g/kg DM | 41 | 42 |
| Total Fermentable Protein | g/kg DM | 48.5 | 53.5 |
| Acid Load | 45.7 | 43.1 | |
| Fibre Index | 152.9 | 156.9 | |
| Glucogenic Energy | g/kg DM | 188.5 | 193.3 |
| Number of samples | 750 | 1,619 |
Source: Trouw GB
Average dry matter this year is only slightly lower than 2024 at 29.9%, but with a wide variation reflecting how quickly crops dried down in the field. Crops that dried quicker may have proved more difficult to compact in the clamp.
Uneven cob fill and less mature kernels, resulting from the heat stress and lower soil moisture, have contributed to a small decline in starch content at 26.2% compared with 28.4% in 2024.
Starch degradability is also slightly lower at 76.8% suggesting that while rumen-available starch remains high, energy release may be marginally lower. Overall energy levels are similar with ME averaging 11.1MJ/kgDM. Average crude protein has increased to 8.3% while the supply of metabolisable protein is slightly lower.
With around 40% of the total dry matter in maize silage represented by the vegetative parts of the plant, fibre digestibility has a significant impact on how well crops will be digested.
“We have seen changes in the make-up of fibre this year, reflecting drought conditions and slightly ‘tougher’ plant material, says Ms England. “While Neutral Detergent Fibre (NDF) has increased to 43.5% DM, Acid Detergent Fibre (ADF) has decreased, indicating that while there is more fibre in the plant, it will be more digestible.
“This is also reflected in lignin content – the proportion of indigestible fibre – which is down from 34.2g/kgDM to 30.2g/kgDM. Combined, these results point to good fibre digestibility meaning cows will be able to make more of this valuable energy source.”
The higher fibre and lower starch levels may result in a slower but more sustained energy release which will enhance rumen stability. This should help balance out high sugar, rapidly fermentable grass silages. Ms England advises ensuring that rapidly and total fermentable energy and protein are in balance and to supplement accordingly.
“The analyses indicate that metabolisable protein supply will be reduced so complementary protein sources may need to supply both rumen-degradable and bypass fractions. Feeds such as rapeseed meal and distillers’ grains will help maintain microbial efficiency,” she concludes.