Despite many people having excellent stocks and nearly all samples showing encouraging feed quality, many farmers are reporting that grass silages are not milking as well as expected. Why is this and what can be done to improve performance for the rest of the winter?
To produce the optimum yield from silage, the starting points are the forage analysis and the rumen. The first thing to acknowledge is that there is no such thing as an average silage. I would recommend that you have your forages analysed monthly throughout the winter as the analysis will change as you move through the clamp.
Once you have the analysis you can consider how the silage will perform in the rumen and this is where many diets are falling down at the moment. On paper the diet is right, but the cows aren’t milking as per the ration plan. This would suggest things aren’t right in the rumen, as ultimately it is what the cow does that tells us if the diet is right.
This year we need to look more closely at grass silage fibre levels which have been very variable this season. Some early cuts contained high lignin due to over- wintered grass. We are seeing a large number of forage analyses where NDF is low and ADF is high, which means the rumen will be short of hemicellulose, essential for the production of glucogenic energy.
High ADF means fibre digestibility is an issue and you will see increased long particles in the dung. If this is the case, then you need to increase the supply of glucogenic energy to the cow but need to do so carefully.
Starch and sugars are good sources of glucogenic energy, but they are rapidly fermented carbohydrates which brings the risk of reduced rumen pH which will also compromise fibre digestion. It is essential that the diet is balanced correctly. When thinking sugars many people think about molasses. There is also an alternative feed source of glucogenic energy which is rumen-inert and an excellent source of energy for glucose production, and like molasses is highly palatable and therefore helps drive intakes.
Another source of energy for your diet, if you are looking for an alternative to rapidly fermenting carbohydrates, would be a rumen-inert fatty acid, of which there are several available depending on your dietary and production requirements.
For more information on general livestock nutrition, molasses, glucogenic energy or rumen-inert fatty acids please contact Andrew at firstname.lastname@example.org or your local FCG office.