By now, farmers across the country are probably worn out at the thoughts of completing fodder budgets and listening to advice around measuring and managing silage stocks and winter feed demand. With much of the focus in recent months being directed at the quantity of silage in the yard, one element that has possibly been forgotten about is the need to test for silage quality.
But why is this important? Well think of it this way: every dairy farmer certainly knows the protein content of their dairy nut for example. And every beef farmer will more than likely know the protein and energy value of their beef ration too. Furthermore, it goes without saying that silage is probably the number one component in winter diets across beef, dairy and sheep farms in Ireland meaning there is no good reason why you shouldn’t know its feeding value too.
Silage sampling on the BETTER Farms
As part of the Teagasc/Irish Farmers Journal BETTER farm beef challenge, all participants must take silage samples at the beginning of each winter. The importance of taking silage samples this year is perhaps even greater than other years due to difficulties experienced on many farms as a consequence of the extreme weather conditions. Once silage sample results have been received, each participant will have the chance to formulate winter diets accordingly, with the help of their local B&T adviser and their BETTER farm programme advisor. In many cases this can go a long way in reducing quantities of silage or meal offered to animals or in improving animal performance.
Table 1 gives the average result of first-cut and second-cut silage samples across the entire group of participant farms. This table alone suggests that both first and second cuts are in-or-around where they need to be. DMD is perhaps the figure that most people will look to first. With average DMD sitting at just under 70% and 69% for first and second cuts, respectively, there is certainly room for improvement. Obliviously some are making the desired 70% plus DMD silage, but there is also a strong cohort still below the magic 70% DMD figure. Going forward, to get the majority of BETTER farms to optimum silage quality, this average DMD figure will need to rise above 72-73%.
It is also worth commenting on the difference in DM% which pretty much reflects the conditions experienced during 2018. First-cut silage averaged a reasonably high 29% DM across all BETTER farms, however, the almost 33% DM average recorded for second-cuts on these farms is remarkably high, but an expected result given the drought conditions towards the latter part of the grass growing season.
Silage sample measures explained
Dry matter (%):
This is the amount of matter remaining after all water has been removed. The energy and protein value of silage is quoted in %DM. 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.
A well preserved silage should have a pH of between 3.8 and 4.5. You can get away with a dry, high-pH silage, however, a wet silage with a high pH, will not keep as well and usually intakes will be low. If pH is below 3.8, this can lead to acidic conditions, a sharp smell and a higher risk of acidosis.
Ammonia-N levels (% of total N):
High ammonia levels show poor preservation. This can be due to high grass nitrogen levels at cutting or low sugar possibly from wet, young grass being cut. Values of <5% indicate excellent preservation, while >15% will lead to reduced intakes.
Crude protein (%):
This measures the protein concentration of the silage. Young leafy reseeded swards will have higher protein values. Inadequate fertiliser applications can lead to lower protein levels.
Values >15% indicate young leafy swards. Too high of a crude protein value (17% +) can be a sign that a good portion of the plant’s protein will be rapidly degradable and thus not easily utilised.
Also, feeding very high crude protein silages during breeding is not advised.
This is the amount of energy in the silage. 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 in suckler cows and liveweight gain in beef stock.
DMD value (%):
DMD stands for dry matter digestibility. This is a measure of the feeding value of the silage expressed as a percentage. Late cut, old swards can have a DMD as low as 55DMD while excellent leafy silage can be > 75DMD. Silage with a high DMD will be digested quicker and lead to higher intakes.
Dry matter: 20-30%
Crude protein: 13.5-17%
ME (Energy): >9.8