For the last few years, the industry has been advising grass silage producers to cut little and often to maximise the energy and protein yield from their silage ground.
Cutting every 4 weeks from the last week of April has been seen to be the holy grail of silage making, creating many small cuts of ‘rocket fuel’ silage, high in metabolisable energy (ME) and crude protein (CP), low in NDF and as much or even more yield than the traditional three cut method across the season.
With more opportunities to apply slurry, a shorter harvesting operation and more consistency in the final product, it seems a win-win for the farmer, nutritionist and certainly for the contractor. Often this is not the case. Of course, there is no denying a higher ME and CP from pretty much all cuts and there is no yield penalty across the whole season, but this is where the gains can end.
First off, there is a larger contractor's bill to pay, which is not always offset by increased milk from forage. The extra ME can often come with higher oil levels that nutritionally, do not bring much to the table and can often create a butterfat slump. The increase in CP can be mainly ammonia, so having little nutritional value. This increase in ammonia can be a result of the crop having less time to use the slurry or nitrogen-applied post-cutting which in turn, is detrimental to fermentation. Another thorn in the side of multi-cut fermentation can be the fact that these light cuts can go from too wet to very dry in a matter of hours, so dry matter (DM) can vary a lot. If it is on the damp side, we see a lot of clamp slipping causing excessive heating and waste, along with some very high lactic silages, due to the high sugar levels in the grass.
Consistency
Consistency is key to high performing herds, whatever the system. Cows love consistency, rumens love consistency and consistency is important for farm businesses. In principal, multi-cut should help consistency, but it can impede it. Cows eat more ‘multi cut’ silage, due to lower NDF reducing the full effect of silage which means you burn through each cut very fast, resulting in more diet changes. As much as we try, each cut does vary and often needs a diet change, whether its due to DM, fermentation characteristics or the unavoidable seasonal variation in grass silage. Moreover, in some cases, due to higher intakes, bought in or poorer quality silage is needed to fill the gap, negating many of the benefits of feeding high quality forage.
NDF
Finally, it is important to consider that the role of forage is not just to provide as much ME and CP as possible, in fact, forage is just that – a forage, a fibre source. Fibre or NDF is often the biggest variable in a dairy ration, so let’s try and make silage with consistent NDF levels, as we can easily balance other nutritional parameters. Why do we so often make so such high quality ‘multi-cut’ grass silage and balance it nicely with 1kg of chopped hay? Often because there is not enough NDF supplied. In most cases by extending the cutting interval by a week for first and second cut and then reverting to shorter cutting intervals, we would get more consistent NDF levels across cuts. Multi-cut techniques have a place and a lot can be gained by reducing cutting intervals, as mentioned earlier, but only if well managed. There are a few points that first need to be considered to reap the rewards:
- Ensure that you have enough forage to account for higher grass silage intakes
- Consider using forage wagons to reduce the cost of production, especially in late season
- Consider delaying first cut by a week and lengthening second cut a 5-week interval, then reverting to a 4-week interval to get more consistent NDF levels and maximise yield of first and second cut
- Layer each cut in the clamp, so all are fed evenly at the same time, reducing ration changes at feed out
- Ensure crops are wilted enough. Better to be too dry than too wet on lush silages
- Use an additive on all cuts to reduce the risk of poor fermentation
- Be sure of your nitrate levels before cutting -test where necessary
- Minimise slurry applications after June because of the risk of contamination and elevated nitrogen levels in the summer and autumn. Make sure low volumes are applied using a shoe or dribble bar
We are often dictated so much by the weather and have to cut silage when we can, throwing all good plans out of the window, but having a plan at least, to maximise your grass silage production will stand you in good stead to increase milk from forage and overall farm utilisation.
