Quality Silage Pays!

Michael Graham, Greenmount Campus, CAFRE and Hugh McCluggage, John Thompson & Sons Ltd

This article is one of a series prepared jointly by CAFRE and John Thompson & Sons, focusing on the key grassland management issues facing dairy farmers during the 2008 grazing season. The articles draw on experiences from the management of the Future Herd at Greenmount Campus, CAFRE managed in partnership with Thompsons, and the Thompsons Milk Manager data from customer’s dairy herds across Northern Ireland.

Silage quality is vitally important for autumn and winter calving dairy cows as a large percentage of the milk produced will be from grass silage. With the ever increasing costs of fertiliser, feed and fuel, this is the year to produce top quality grass silage. Research at AFBI Hillsborough has shown that early cutting, leading to high digestible silage, improves both milk yield and quality (see Table 1).

Table1: Effect of silage quality on milk yield and quality

	9.9	11.2	11.7
Silage Intake (kg MD/day)	8.1	10.0	10.7
Milk Protein (%)	3.17	3.22	3.35
Milk Fat (%)	3.68	3.68	3.77
Milk Yield (litres/day)	26.3	28.2	28.9

At present day costs, the benefit of moving from 9.9 ME silage to 11.7 ME silage would be £140/cow or £14,000 for a 100 cow herd over the six winter months. Remember it takes the same fertiliser, diesel and contractor costs to make average silage compared to top quality material without the benefits.

What is high quality silage?

At Greenmount Campus CAFRE, the following targets are set each year for their silage-making programme:-

ME 11.5 - 12.0 MJ/KG D.M.

Crude Protein 14 - 16 percent D.M.

Dry Matter 25 - 30 percent

Intake Potential 100+

Michael Graham, the Farm Manager, is in charge of silage-making at the College. Over the past number of years Greenmount has consistently made this type of silage despite sometimes difficult weather conditions. Analysis of last year’s silage are as follows (Table 2).

Table2: Silage analysis from 2007

	31.5
pH	3.85
Ammonia (% Total N)	7.4
Protein (% DM)	15.4
ME (MJ KG DM)	12.1
'D' Value (%DM)	77
Silage Intake (g/KG)	112

How can this quality silage be made?

Although early cutting reduces the yield obtained from the 1^st cut, yields from other cuts will increase so, overall, early 1^st cut will have little effect on the total yield of grass/silage produced over the year.

Set yourself a target cut date and work towards it (Table 3).

Table 3: Target cutting dates for good quality silage

	TIME
1st	Early May
2nd	Mid-late June
3rd	End July - early August

Other factors to consider are:-

Sward type.
Fertiliser and slurry policy.
Rapid wilting.
Ensiling technique.

Sward type:

High yields of quality silage start with the sward itself. To maximise the output of silage, regular re-seeding is important to achieve the increased potential of new varieties. Some general principles to adhere to when re-seeding are:-

Keep the mixture simple, use two or three compatible varieties.
Use about ⅓ tetraploid and ⅔ diploid perennial ryegrass.
Use early and mid-season varieties.
Where management allows early grazing and short cutting intervals, introduce new hybrid varieties.

Fertiliser and Slurry Policy:

According to the Nitrate Regulations, the nutritive value of slurry and subsequent availability must be taken into consideration when it comes to fertiliser choice and rates applied (see Table 4).

Table 4: Typical nutrient content of animal slurry

	Total Nutrients	Units/1,000 Gallons	Units/1,000 Gallons	Units/1,000 Gallons	Available Nutrients Units/1,000 Gallons	Available Nutrients Units/1,000 Gallons	Available Nutrients Units/1,000 Gallons
Slurry	DM%	N	P	K	N	P	K
Dairy	6	27.3	10.9	31.8	9.5	10.9	28.6
Pig	4	36.4	18.2	22.7	18.2	18.2	20.5

Where possible, most slurry should be applied to silage swards. When applying different rates of slurry, fertiliser levels can be adjusted accordingly.

Nitrogen is the key element influencing the yield of grass for silage. Where soil analysis shows phosphate indexes above 2, then straight N can be used. If potash levels are low, then a nitrogen/potash fertiliser such as 27:0:6 or 23:0:10 are appropriate. At Greenmount, phosphate levels are good so 80 kg N/ha or 65 units of nitrogen per acre were applied for 1^st cut together with 3,000 gallons of cattle slurry/acre.

Ensiling techniques

One of the principle factors influencing the intake potential of silage is its fermentation pattern. Achieving a good fermentation involves:-

Cutting at 5 cm above soil level.
Ensure machinery is properly set to avoid soil contamination.
Ensile quickly and efficiently.
Use an effective inoculant to enhance the fermentation.
Cover the silo each night to exclude air.
Consolidate during filling and seal the silo immediately with a new sheet, covered with an old sheet all weighted down to minimise top waste.

Rapid Wilting

High intake silage will have a dry matter content of 25 - 30 percent. It is important to achieve this in less than 24 hours to minimise field losses. Grass will have to be spread out and then rowed up in slow drying conditions to achieve this.

Summary

Improving the feeding value of grass silage must be a priority for this year. The production of high intake, high digestibility grass silage which is capable of supporting high levels of animal production will continue to be the cornerstone of winter milk production.