Are you going to test the quality of your silage before you start feeding it? For many, particularly drystock farmers, the answer to that question will be no. I think the main reason many farmers do not take silage samples is that they don’t see the benefit of it. They possibly do not know how to interpret a silage sample result and even if they did, it’s probably not going to change their feeding habits this winter. I think that’s an unfortunate attitude to have, but when you tease it out, its one that could certainly be changed.

The benefits

If you were to ask any farmer about the protein content of their dairy, beef or sheep nut, they would more than likely be able to give you an answer. Yet ask them about their silage quality and very few will have that information. The reason for this might be because we understand and see a benefit of the feeding values of concentrates.

Suckler farmers know that weanlings will need high protein to sustain growth, while their finishing stock need energy instead. Each dairy farmer will have the nutritional value of their nut down to a tee. What many do not understand is that the nutrient value of their silage holds the exact same importance.

Beef

Table 1 shows the effect silage quality has on weight gain in beef animals.

According to a number of studies at Teagasc Grange, silage with higher dry matter digestibility (DMD) resulted in better feed intakes and weight gains for finishing cattle. The benefits include shorter days to finish (lower total silage DM required), lower daily concentrate intakes to achieve target daily gains and lower costs for slurry spreading and labour. Similar benefits are incurred with higher DMD silage fed to weanling cattle and suckler cows. Table 2 shows the winter feed requirements of suckler and beef stock depending on silage quality.

Remember, every extra kilo of concentrate fed per day costs approximately 25c/head. Potentially, that’s an added €40/head over the course of a winter.

Dairy

For milking cows, the benefits of higher DMD silage are: improved forage intake, more milk solids and milk from forage, better rumen health and lower concentrate feeding levels (Table 3).

Cows fed high-quality silage (over 75% DMD) require 3kg-4kg/head less concentrate to achieve similar milk solids output than cows fed average quality (69% DMD) silage. Dairy heifers fed 70% DMD silage and higher have improved daily gains during their first winter.

Reading your sample

Your silage test report will detail a range of nutritional values. DM, DMD, energy and pH are the main ones to know, while Table 4 gives a comprehensive breakdown of good and bad silage values.

Dry matter (DM%)

This is the amount of matter remaining after all water has been removed. The higher the DM, the higher the intake of energy and protein will be for every 1kg of fresh weight silage an animal eats. In general, lower DM silage will have lower intakes and higher DM silage will have higher intakes. The DM range is 15-45% but optimum for intake is 28-32%.

Dry matter digestibility (DMD%)

This is the key measure of quality. It determines intake and energy values per kg of DM. Silage with a high DMD will be digested quicker and lead to higher intakes. Late cut, old swards can have a DMD as low as 55% DMD, while excellent leafy silage can be > 75 % DMD. Values of 74%+ DMD are suitable for high performance animals. DMD below 66% is sub-maintenance feed for most classes of stock.

Energy (ME/UFL/UFV)

Increased energy values boost animal performance and reduce cost of supplementation. Young grass will have the highest energy while mature grass will have lowest energy. The younger and dryer the grass, the more energy the silage will supply for milk production and liveweight gain. Top quality silage can be >0.90 UFL, but values close to 0.70 UFL are more common.

pH

This is a primary indicator of preservation quality and fermentation efficiency, as well as the acidity of the final silage product. Target pH depends on the DM content of the ensiled crop. A pH of 3.8 to 4.2 indicates good preservation at 28% DM. Dry or wilted crops (>28% DM) can be well preserved at up to 4.5 pH. Wet silage with pH values of > 4.2 are generally poorly preserved. Where silage pH is <3.6, adjust diets to ensure correct rumen pH.