Improving silage quality with reseeding
Dr. David Lawrence
Head of Nutrition, Agritech
The basis for dairy production in Ireland is simple; we have a suitable climate for growing good quality grass and forage. We capitalise on this by adopting our farming practices to capture as much quality grass as we can during the growing season and turn it into milk or growth performance. However, we treat silage as a stand-alone crop and in doing so we treat it as something different to growing high quality grass, we treat it as filling the pit or getting good value for money when we cut.
We lose sight of the objective to capture our grass quality and turn it into milk yield or animal growth for the months we cannot grow or graze grass. How do we grow better quality grass? At this stage every dairy farmer knows the obvious answers; improve soil fertility, measure grass and offer cows and young stock the highest quality grass you can, ensure you reseed old pasture with highly productive perennial ryegrass’s that feature on the recommended list. Interestingly, these are the same answers you would expect when discussing how to improve silage quality. Why is it so difficult to make grass silage? Grass that is grazed directly is often over 80% digestible dry matter (DMD), yet the average grass silage quality tends to stay around 68% DMD. The reasons for losing DMD are ranked below from largest to lowest cause.
1. Cutting later (every week past mid-May can reduce DMD by over 3 units) cutting early June could be a total loss of 8 units of DMD.
2. Carrying through a yellow base in the sward from the winter, this could lose over 7 DMD units.
3. Having swards with a low level of ryegrass, will reduce the sugar available for fermentation and increase the delay in cutting date as they are slower at utilising nitrogen.
4. Slow fermentation can lead to large levels of DMD decline.
5. Heating at the feed face will reduce DMD further.
Correct cutting time is often considered 50% ear emergence, which means half the crop has the seed head emerging from the grass. This is linked to the grass variety you choose, as intermediate heading varieties such as Galgorm, Aberspey and Aberclyde will be ready for cutting a week ahead of late heading varieties bringing you earlier yield, which is one of the benefits of Agritech’s Tipperary Grass 3A mixture. Recently reseeded pasture has a larger inclusion of ryegrass which will grow quicker and utilise nitrogen at a faster rate than old permeant pasture.
Reseeded swards will also contain a higher concentration of sugar in grass, which is required for successful fermentation. Coupled with the addition of a silage inoculant such as GrasZyme Sugarboost, reseeding silage ground can improve early silage yield, and preservation which will maximise the DMD we can retain from our ensiled grass. Apart from autumn/ spring sward management, every management point on maximising DMD from grass can be influenced by either reseeding or using a silage inoculant.
Why not get in touch with your local Agritech Sales Advisor for any advice you may need on improving your sward and silage quality.