Steps to making better quality silage
The level of quality achieved has a major effect on the cost of silage and the performance of the animals being fed.
ilage makes up a least a quarter of the annual diet on most beef and dairy farms. The level of quality achieved has a major effect on the cost of silage and the performance of the animals being fed. If high digestibility grass is harvested, we should be able to achieve very high performance. Research suggests that we have not been ambitious enough in terms of the quality of silage we have targeted and consequently, the possible animal performance it can deliver.
The key steps outlined below should be followed to produce silage of the desired quality at a reasonable cost.
The farmers that consistently make good quality silage always have a plan in place. The plan requires short term and long term planning to maximise yield and quality. Put pen to paper and write out a complete plan of how appropriate quality silage will be successfully made. Some points in the plan will have long-term effects for several years (e.g. improving soil fertility and reseeding), while others will relate specifically to the upcoming harvest. Decide on what fields to harvest, the harvest date and the contractor to use. Flexibility will be vital for the plan to succeed, because of the need to adapt to our variable weather.
The first step to improving silage quality is to decide how much and what type of silage is needed. The quality of silage required will depend on the type of animals being fed. Low productivity animals need poorer quality silage than high performance animals such as finishing cattle.
For spring calving suckler herds, dry cows will need about 6 bales (1.1 tonne DM) per cow 68 DMD silage with all remaining silage at higher quality (72+).
Dairy herds (spring calving) need about 0.8t DM per cow of 68 DMD silage with 100% of the remainder as high quality (72+). At least 50% of total silage will need to be high quality Calf-to beef-systems need 100% of silage at 72+ DMD.
Docks have a DMD of just 65% reducing to 50-55% when headed out. Docks should be controlled in early May or prepare to spray them in the regrowth following the 1st cut.
Harvest date is the most important factor affecting silage quality. As harvest date is delayed quality declines. Once seed heads appear DMD will be around 70% at most, and will drop by 1 point every 2-3 days after that. A lodged crop lying in continuously wet conditions can lose up to 9 percentage units digestibility in a week. Don’t decide to harvest on a calendar date chosen too early. Monitor the silage fields from early May and then book the contractor in time, keeping a close eye on weather forecasts.
Monitor the development of swards. Check out the services and costs of available contractors, and book your contractor of choice in time. The main step to improve average quality is cutting from mid-late May rather than into mid-June.
Well-managed silage swards closed from late March should have good yields of 5.5 to 6t DM per ha (9-10 tonnes per acre fresh) ready for cutting by late May. Using a ‘one big first cut’ approach to make silage increases risk of fodder shortages because second cut yields and annual grass production are reduced by pushing first cuts into mid-June.
A common reason for putting off cutting silage is concern about Nitrogen. A useful guide for fertiliser N is that grass uses 2.5 kg N (2.0 units) per day on average, so final N should be applied approximately 50 days before planned cutting date. However, this guide should not be the only factor used to decide cutting date. If weather conditions are suitable for cutting, test the grass crop for sugars rather than sticking rigidly to the ‘2-unit rule’; the crop can be safely harvested sooner depending on conditions. High sugar content allows the crop to ferment quickly in the pit/bale, reducing pH and preserving the crop correctly. If sugars are over 3% then the crop will ensile readily, at 2-3% wilting will be beneficial, while below 2% an additive will be required. Mow in the evening when sugars are highest if possible.
Wilting grass to 28-20% dry matter is very beneficial to good preservation, especially if sugars are less than 3% and nitrate is somewhat elevated. Only attempt to wilt a crop if it will be genuinely drying while on the ground. Wilting reduces silage DMD through a loss of available nutrients. The decline in digestibility due to wilting depends on the time between mowing and ensiling. The wilting period should be kept as short as possible, every day (24 hours) of wilting can reduce silage DMD by between 0.5 to 2 percentage units. Tedding out for 24 hours is the recommended approach; grass will not dry enough in large rows even if left for 36 hours.
Do everything necessary to ensure the silage preserves properly, excellently preserved silage will have a digestibility close to that of the grass from which it was made while poorly preserved silage could lose up to 5% units DMD and have low intake characteristics. Therefore, if using an additive, ensure the full rate of an appropriate product is applied evenly, fill the silo quickly and seal perfectly, ensure any effluent can quickly escape from the silo and is safely collected.
With earlier cutting there is a great opportunity to make a cost-effective second cut of silage in July.
