Silage samples have been collected across the programme farms and analysed for feed value.

The next step is to use these results to draw up winter feeding plans for ewes in mid and late pregnancy.

By knowing the level of dry matter energy and protein within forages, supplementary concentrate feeding can be tailored to each individual farm.

Ration type can also be tailored to complement silage, as some forage results are higher in protein than others. In such instances, a predominantly cereal-based ration may suffice.

On the flip side, where forages have lower levels of protein, then there is greater need to source a concentrate ration in the region of 18% to 20% crude protein.

The final part of the jigsaw with winter feeding is the body condition score of ewes in the run-up to lambing.

If ewes are carrying plenty of body condition over winter, and forage analysis shows a high feed value, there will be a need to restrict fodder intakes.

This is easier said than done as it takes a bit of planning. Firstly, ewes need to be batched, according to condition score, and the number of lambs being carried.

Secondly, when restricting silage, it is crucial that all animals can access forage at the same time. If not, the dominant ewes will eat according to appetite, which increases the risk of problems at lambing time.

By providing sufficient feed space, silage allocation can be cut back by 10% to 20% as all ewes can come forward and eat when fresh forage is offered.

Repeat sampling

While silage sampling is always advised, it is not good practice to base all feeding decisions throughout winter on the strength of one sample.

Taking a couple of follow-up samples is recommended, as the silage half the way through the pit will differ from the first couple of grabs when the clamp was opened.

The same thing will happen with silage bales from different fields. Feed value will also change depending on whether silage is first, second or third cut.

There may also be bales made from surplus grass that was getting too strong on the grazing platform to consider.

Taking a few samples for testing will help account for such factors and, as the farms have access to mobile sampling kits through the CAFRE advisory service, multiple sampling is much more practical.

What to look out for in a silage analysis result

When silage is analysed, there will be a whole range of factors measured. They are usually presented together with a numerical figure.

At first glance, the results can be hard to interpret. However, rather than getting hung up on every measurement, outlined are a couple of key things to look for and target figures.

Dry matter (DM%)

Dry matter is basically the amount of material left once the water content has been removed. A good target for grass silage is a dry matter between 30% and 35%. The lower the DM%, the wetter the silage and vice versa. Wet silage will have lower intake potential.


This indicates how well the silage has fermented and should be around pH 4 to 4.5. A higher pH usually indicates a poorly fermented forage that is more prone to spoilage, mould and heating once fed out.

Below this pH range can increase rumen problems as the forage is extremely acidic.

Crude protein (CP)

Protein drives weight gain and milk production. Grass swards cut with a high level of leaf content present, and little stem or seed heads, usually have higher protein levels.

Target levels should be around 13% to 15% for grass/clover swards. Below this level, there will be a greater reliance on supplementary concentrate feed to drive liveweight gain and milk.

Metabolisable energy (ME)

ME refers to the energy content that silage will provide in the animal’s diet. As is the case with protein, grass swards with high leaf content will have a higher ME and vice versa.

Good-quality silage should have an ME content above 11 and ideally around 11.5 to 12 MJ/kg DM. Silage with a higher ME will need less supplementary concentrate to drive animal performance.

DMD or D-value

The DMD or D-value is a good overall indicator of silage quality. Ultimately, the higher the DMD%, the higher the feed value of the forage.

The silage is likely to be more digestible, so animals will have higher intakes which has a positive effect on performance.

A value above 70% reflects good-quality silage with average quality around 65% to 67%.


Although it is not a direct indicator of feed value, the ammonia content of silage again indicates how well fermented the crop is.

High ammonia levels can indicate grass was cut before the nitrogen in fertiliser applications had been utilised fully.

Target ammonia levels should be between 5% and 10%. Higher than this and silage will be brown or black in colour with a rancid smell. It will also heat once fed out.

Neutral detergent fibre (NDF)

Fibre is also important. High fibre silage is harder to digest, so animals struggle to access the nutrients in the forage.

It will also slow down digestion and intakes, so animals will eat less.

If fibre is insufficient, the animals will pass loose dung. Ideally, target a fibre content between 45% and 50%.

How good are the first- and second-cut crops?

Tables 1 and 2 outline the results of the silage samples for first- and second-cut analysed on the programme farms over the past month.

All nine farms made a first cut with the median harvesting date being 9 June 2022, around one week earlier than the previous year.

Overall, feed value is marginally better as a result, despite weather conditions being extremely challenging during May and June.

Dry matter is low at 23.8% compared to an average dry matter content at 30% last year. Northern Ireland experienced wet conditions in early summer, limiting the opportunities to wilt grass for 24 to 48 hours before lifting or baling.

Interestingly, the later cutting dates have a higher dry matter content and would coincide with more settled, drier weather over the summer. Wet silage may be an issue when fed out in late winter.

However, despite the lower dry matter, this year’s forages have higher energy levels and higher D-Value readings when compared to last year.

The 2022 average for ME is 11.02 MJ/kg DM compared to 10.98 last year. The earlier harvesting date also helped to lower the fibre content, making silage more digestible.

Early cutting

The earliest crop saved was 30 May on Dermot McAleese’s farm with grass ensiled in the pit. Despite this, the analysis is a bit of a mixed bag and possibly reflects the difficult weather conditions at the time.

Dry matter is below the optimum level at 23.38%, although this may increase as Dermot makes progress through the pit. Last year, dry matter was 29%.

Energy is 10.69 MJ ME/kg DM and is again below the optimum level.

Dermot has been busy reseeding silage swards in recent years.

While young, leafy grass swards were harvested, the lower dry matter would have reduced the water soluble carbohydrate content and this would have reduced the energy content.

In contrast, cutting early before grass swards matured to seed head has helped to produce a crude protein content above 15%.

Late cutting

The latest first cut was on Roy and Marlyn Mayers’ farm with a July cut. However, this has to be put in context as the Mayers do not lose off a set area of grass for silage.

Instead, they choose to make silage on their grazing platform throughout the summer as a means of ensuring there is high-quality grass available for ewes and lambs.

This is evident from the analysis outlined in Table 1. Despite a cutting date of late July, energy is excellent at 11.39 Mj ME/kg DM with crude protein content above 13% indicating, young, leafy grass swards being harvested.

Overall, the bales analysed have a D-Value of 71.16 which equates to a DMD content in the region of 76%.

Second cut

Analysis of the second-cut silage shows an improvement in dry matter and protein content and overall, forage analysed is ideal for dry ewes in late pregnancy.

The median cutting date was around 5 August and back then, harvesting conditions were much more favorable for silage compared to June.

Dry matter averaged 28.37% and will make silage easier to handle once fed out. Protein is higher with the average reading at 14.43%, although energy is slightly down from first-cut levels.

Fibre, pH and ammonia levels are all ideal which indicates that the samples were taken from well fermented forages.

Further samples

The results from the 2022 silage analysis are generally good, but follow-up samples will be taken to give more information for tweaking feed plans.

At the end of the day, silage will be fed to ewes from mid to late pregnancy. The aim on the farms should be to have animals in ideal body condition by the end of the year.

Once silage is introduced, it only needs to maintain condition and at the outlined results, this is more than possible.

Once ewes lamb down, animals will go back to grass as early as possible and this will help to drive milk production post-lambing, along with supplementary concentrates as necessary.

Read more

Calving heifers at 36 months ‘leaves behind’ €250/ha – Teagasc

Thrive: diets to keep stock on target this winter period