XVth International Silage Conference Proceedings 53
Influence of cutting height and use of additives on silage quality
U. Wyss
Agroscope Liebefeld-Posieux Research Station ALP, 1725 Posieux, Switzerland;
Email: ueli.wyss@alp.admin.ch
Introduction The silage quality is influenced by different factors. Especially in autumn, it is difficult to pre-wilt the forage and there is a higher risk of soil contamination. The objective of the study was to investigate the influence of cutting height, pre-wilting degree, and use of silage additives on silage quality.
Materials and Methods In autumn 2006, forage of a ley of the fifth growth was cut at two different cutting heights, 7-8 cm (H) vs. 3-4 cm (L). A part of the forage was ensiled directly (A) and the remainder was tedded and ensiled the following day at a higher dry matter (DM) content (B). The forage was ensiled in 1.5 l capacity laboratory silos with or without a chemical additive and two inoculants. Inoculant X contained Lactobacillus plantarum, inoculant Y contained
Pediococcus acidilactici, Lactobacillus paracasei, and Lactobacillus lactis. After a storage period of 160 d the silos were opened and the nutritive values, pH, and the concentrations of ammoniac and fermentation acids were determined. The DLG-points were calculated (DLG, 2006).
Results and Discussion In a first step, the silages without additives were compared. The pre- wilting degree (PW) and the cutting height (CH) influenced significantly the DM, ash, sugar, and net energy content (Table 1). In forage (A) the ash content was higher in L than in H (Table 1).
Therefore, there were also big differences in the net energy content. In forage B the ash content was similar between the two cutting heights. The crude protein content was only influenced by the CH and the crude fiber content was not influenced by the two analysed factors. The pH, fermentation acids, and ammonia were mainly influenced by the PW. No or only traces of butyric acid were produced in the silages, which might be caused by the high nitrate content of the fresh forage. The silages of forage A showed relatively high pH values and high content of acetic acid. Therefore, these silages had low DLG-points. By pre-wilting, the acetic acid content was slightly reduced, and these silages had higher DLG-points. But the quality of silages was still assessed as mediocre.
In a second step, the effects of additives were measured. In forage A the chemical additive influenced the ammonia proportion positively in variant L and negatively in variant H (Figure 1).
Differences were also found between the two inoculants. With inoculant X the ammonia-N proportion and the DLG-points were not improved in comparison to the variant without a silage additive (Figures 1 and 2). However, with inoculant Y the ammonia-N proportion was reduced and the silage quality was improved, especially in the silages with the higher DM content.
Conclusions In autumn, forage can have a high soil contamination, especially when the cutting height is low. The correct silage additive can improve silage quality under these conditions.
References
DLG. 2006. Grobfutterbewertung. Teil B – DLG-Schlüssel zur Beurteilung der Gärqualität von Grünfuttersilagen auf Basis der chemischen Untersuchung. DLG-Information 2/2006.
July 27-29, 2009 – Madison, Wisconsin, USA 54
Table 1. Influence of pre-wilting (PW) degree and cutting height (CH) on nutritive values and fermentation parameters in silages without additives
Pre-wilting Low (A) Medium (B) SE Significance
Cutting height H L H L PW CH PW*CH
Dry matter, % 16.7 16.6 24.1 21.4 0.19 ** ** **
Ash, g/kg DM 177 267 170 173 7.8 * * *
Crude protein, g/kg DM 224 183 216 205 2.1 NS ** **
Crude fiber, g/kg DM 242 231 236 244 2.7 NS NS NS
Sugar, g/kg DM 7 5 8 8 0.1 ** ** *
NEL, MJ/kg DM 5.6 4.7 5.7 5.5 0.05 ** ** **
pH 4.9 4.9 4.6 4.6 0.02 ** NS NS
Lactic acid, g/kg DM 80 67 130 112 2.2 ** ** NS Acetic acid, g/kg DM 87 77 55 53 2.7 ** NS NS Propionic acid, g/kg DM 9 9 2 2 0.5 ** NS NS Butyric acid, g/kg DM 0 0 3 3 0.1 ** NS NS
Ethanol, g/kg DM 7 7 4 2 0.8 * NS NS
NH3-N/N total, % 12.5 14.5 10.9 11.7 0.26 ** * NS
DLG-Points 20 28 49 52 2.9 ** NS NS
NEL: Net energy for lactation.
NS = P>0.05; * = P<0.05; ** = P<0.01.
02 46 8 1012 1416 1820
A-H A-L B-H B-L
NH3-N/N total, % . without additive
chemical additive Inoculant X Inoculant Y a
b a
c
ab c
a bc
a b a
b b bc
a
c
Figure 1. Effects of pre-wilting-degree (A=low; B=medium), cutting height (H and L), and silage additives on ammonia-N proportion. Values within the same PW and CH variants with different letters differ significantly (P>0.05)
100 2030 4050 6070 8090 100
A-H A-L B-H B-L
DLG points without additive
chemical additive Inoculant X Inoculant Y b b b
a b
a
b b c
b b a
b b b
a
Figure 2. Effects of pre-wilting-degree (A=low; B=medium), cutting height (H and L), and silage additives on DLG-points. Values within the same PW and CH variants with different letters differ significantly (P>0.05)
