FEEDING
FOCUS April 2017 • Issue 23
Can you improve silage quality? Every additional 1,000 litres of milk obtained from forage can reduce production costs by as much as two pence per litre. With the grass silage harvest just around the corner, now is the time to assess your grass silage strategy. Impact of weather Winter temperatures and rainfall have a significant impact on the quality of grass silage. The weather for the last four winters (Dec, Jan, Feb) has followed the pattern below impacting on the quality of subsequent harvests. 2013/14
2014/15
2015/16
2016/17
Average temperature (°C)
5.2
3.9
5.5
5.0
Average rainfall (mm)
545
367
529
252
(A)
(B)
(C)
(D)
Source: MET office
Silage quality is affected by warm, wet winters because high levels of rainfall increases the risk of leached nutrients and higher temperatures allow continued grass growth which utilises energy. Harvest 2014
Harvest 2015
Harvest 2016
Dry Matter (%)
31.9
32.8
35.1
D value (%DM)
67.12
68.9
66.0
Protein (%DM)
13.1
13.4
NDF (%DM)
54.9
47.4
(A)
(B)
(C)
What effect can improved silage quality have? Higher silage D value (digestibility) can mean improved forage intakes, increased milk yields and lower concentrate feed rates. The table below shows the milk yield for dairy cows fed different silage quality at two concentrate feed levels. Cows fed higher quality silage (79 D) require less concentrate to achieve similar milk outputs than cows fed average quality silage (69 D). Concentrates (kg/cow/day) Silage D value (%DM)
4
8
79
29.1 litres
32.8 litres
69
24.7 litres
27.3 litres
Difference
-4.4 litres
-5.5 litres
Source: Teagasc
Is high quality silage achievable? Comparison between analysis of first cut silage taken from the UK and Netherlands show high D value silage is possible if key management areas are focused on. UK
Netherlands
Difference
Dry Matter (%)
32.1
45.4
+13.3
13.4
Crude Protein (%DM)
13.4
17.2
+3.8
52.7
D value (%DM)
68.3
79.3
+11
Source: ForFarmers
Source: ForFarmers
What does that mean harvest 2017 has in store and is there anything you can do to help maximise silage quality?
Focus areas for quality silage: 1. Cutting strategy Balance the timing of first and subsequent silage cuts in order to maximise both silage quality and quantity. Whilst an early first cut can produce lower tonnage, grass quality will be higher and further silage cuts will achieve better yields. Increase cutting frequency, i.e. cut every 35 days and more often for higher D value silage.
3. Silage additives If used correctly, a crop-specific inoculant will help improve silage quality, stability and preservation. Look for additives that meet the needs of your crop.
Early Cutting
27-35% High Dry Matter – aerobic stability problems • Prevent yeast and mould growth • Reduce heat and lost energy
Conventional Cutting
1st Cut
2nd Cut
1st Cut
2nd Cut
ME (MJ/kg DM)
11.8
11.4
11.3
11.1
Yield (t DM/ha)
4.2
4.1
5.5
2.5
Total yield (t DM/ha)
8.3
8.0
Energy harvested (MJ)
96,300
89,300
Milk yield potential (litres)
18,519
17,173
Adapted from: Thomas, Bax and Osman
2. Harvesting Harvesting grass silage at the correct time significantly improves its digestibility. Carry out regular visual checks of silage fields and cut grass before heading to ensure the best quality silage. Precut grass analysis is useful to help assess nutrient content of grass and potential fermentation issues once clamped. Key pre-cut nutritional parameters are: Analytical Result
Value
Dry Matter (%)
20.0
Water Soluble Carbohydrate (%DM)
15.0
Nitrate (%)
0.15 (1500mg/Kg)
Cut grass mid-morning or early afternoon to minimise moisture levels and maximise sugar content. Ensure a 24-hour wilt (36 hour wilts should be the maximum for clamp silage) to achieve an optimal DM content of around >30%. Encourage rapid re-growth and reduce soil contamination by cutting at a height of 7.5cm.
<27% Low Dry Matter – fermentation problems • Silage requires a rapid pH drop • Preserve protein and stop secondary fermentation
Low DM
20%
25%
Fermentation
High DM
30%
35%
40%
Grass Silage DM%
Aerobic stability
4. Clamp To prevent spoilage, clear the clamp of any sources of contamination such as mud or old silage. To maximise consolidation the clamp should be filled in thin layers (approximately 30cm/12 inches) and ensure that silage is well rolled. Well-weighted top sheets are essential to create stable, well-preserved silage. Consider using side sheets to help construct an airtight seal. Oxygen barrier layers under a thicker top sheet can also reduce shoulder and surface waste. 5. Feed out Seal the clamp for a minimum of four weeks (six if possible) to allow a complete fermentation. It is very important you understand the quality of your silage. Dry NIR (Silage Manager) silage analysis provides accurate assessment of silage nutrient content and fermentation profile. Take a core sample when silage is sealed and then regular face samples to ensure accurate rationing through the feeding period.
For more information about maximising milk production from your forage, please contact your ForFarmers Account Manager.