The moisture concentration at the time of ensilaging was greater (P ≤ 0.05) in late-maturing hybrids (3211, CP4100SV2P, CP5000SAS3122 and E105) relative to early maturing hybrids (0526AM, P9608Q and P0157AMXT). We found no difference in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium (Ca), P, magnesium (Mg) and sulfur (S) among hybrids (results not shown).
The starch concentration ranged from 14.7% to 34.5% among hybrids and was greater (P ≤ 0.05) in early maturing hybrids relative to late-maturing hybrids. The silage pH was lower (P ≤ 0.05) in late-maturing hybrids relative to early maturing hybrids (Table 1). Concentrations of lactic and acetic acid were greater (P ≤ 0.05) in late-maturing hybrids relative to early maturing hybrids.
The ethanol concentration was low in all silages (Table 1). Ammonia as a percentage of CP was low, ranging from 3.7% to 5.2%, and did not differ among hybrids (Table 1).
Table 1. Silage acidity (pH) and concentration of organic acids, ethanol and ammonia in silage corn hybrids (1) ensiled at different maturities.
|
26AM |
AMXT |
99RA |
3211 |
VT2P |
SV2P |
SE |
P |
pH |
3.91ab |
3.86bc |
3.87abc |
3.71f |
3.84bcd |
3.77def |
0.03 |
<0.001 |
Lactic acid, % |
6.02cde |
5.76cde |
6.34abcde |
7.72ab |
6.42abcde |
6.72abcd |
0.72 |
0.003 |
Acetic acid, % |
1.46bcd |
1.53abcd |
1.64abcd |
2.18a |
1.83abc |
1.71abcd |
0.29 |
0.016 |
Butyric acid |
ND2 |
ND |
ND |
ND |
ND |
ND |
|
|
Propionic acid |
ND |
ND |
ND |
ND |
ND |
ND |
|
|
Total acids |
7.47bcd |
7.28bcd |
7.64bcd |
10.30a |
8.25abc |
8.43ab |
0.91 |
<0.001 |
Lactic:Acetic3 |
4.13 |
3.83 |
4.16 |
3.67 |
3.71 |
3.74 |
0.39 |
0.111 |
Lactic, % total |
0.5 |
79.2 |
80.6 |
78.7 |
78.7 |
78.8 |
1.6 |
0.102 |
Ethanol, % |
0.48ab |
0.44ab |
0.44ab |
0.48ab |
0.42ab |
0.33b |
0.07 |
0.035 |
Ammonia, % CP |
4.46 |
4.25 |
4.55 |
5.18 |
4.83 |
4.80 |
0.45 |
0.279 |
Table 1 (cont.). Silage acidity (pH) and concentration of organic acids, ethanol and ammonia in silage corn hybrids (1) ensiled at different maturities.
|
3122 |
E105 |
5467 |
7AMX |
608Q |
4L37 |
SE |
P |
pH |
3.75ef |
3.75ef |
3.82cde |
3.89abc |
3.89abc |
3.94a |
0.03 |
<0.001 |
Lactic acid, % |
7.95a |
7.25abc |
5.46de |
4.74e |
5.10de |
6.23bcde |
0.72 |
0.003 |
Acetic acid, % |
2.02ab |
2.05ab |
1.43bcd |
1.17cd |
1.10d |
1.42bcd |
0.29 |
0.016 |
Butyric acid |
ND2 |
ND |
ND |
ND |
ND |
|
|
|
Propionic acid |
ND |
ND |
ND |
ND |
ND |
|
|
|
Total acids |
9.97a |
9.96a |
6.88bcd |
5.92d |
6.20bcd |
7.65bcd |
0.91 |
<0.001 |
Lactic:Acetic3 |
3.57 |
3.37 |
4.06 |
4.04 |
4.64 |
4.45 |
0.39 |
0.111 |
Lactic, % total |
77.3 |
77.1 |
79.9 |
80.1 |
82.2 |
81.5 |
1.6 |
0.102 |
Ethanol, % |
0.39b |
0.32b |
0.33b |
0.41ab |
0.48ab |
0.57a |
0.07 |
0.035 |
Ammonia, % CP |
4.95 |
4.58 |
4.51 |
4.60 |
3.72 |
4.66 |
0.45 |
0.279 |
126AM = Mycogen 0526AM; AMXT = Mycogen 1247AMXT; 99RA = Dairyland 3099RA; 3211 = Dairyland 3211; VT2P = Croplan CP3899VT2P; SV2P = Croplan CP4100SV2P; 3122 = Croplan CP5000SAS3122; E105 = NK E105; 5467 = Legacy L5467; 7AMX = Pioneer P0157AMXT; 608Q = Pioneer P9608Q; 4L37 = Mycogen TMF94L37.
2Not detected.
3Lactic acid-to-acetic acid ratio.
Means within a row with different superscripts differ (P ≤ 0.05).
Differences in silage quality among hybrids largely resulted from differences in moisture concentration at the time of ensiling. Forage moisture concentration at ensiling has substantial effects on silage fermentation (Muck and Kung, 2007). Silage pH, and concentrations of lactic acid, acetic acid and total acids were greater (P ≤ 0.05) in hybrids ensiled at 72% moisture (Table 2).
Table 2. Effect of moisture concentration at ensiling on silage pH, and concentration of organic acids, ethanol and ammonia.
|
60% moisture |
62% |
64% |
66% |
69% |
72% |
SE |
P |
pH |
3.90ab |
3.92a |
3.87bc |
3.83c |
3.76d |
3.73d |
0.022 |
<0.001 |
Lactic acid, % |
5.56c |
5.49c |
6.04bc |
5.94bc |
6.98ab |
7.83a |
0.546 |
0.001 |
Acetic acid, % |
1.28c |
1.30c |
1.58bc |
1.63bc |
1.88ab |
2.10a |
0.204 |
0.002 |
Butyric acid |
ND1 |
ND |
ND |
ND |
ND |
ND |
|
|
Propionic acid |
ND |
ND |
ND |
ND |
ND |
ND |
|
|
Total acids |
6.83b |
6.78b |
7.46b |
7.57b |
9.20a |
10.13a |
0.695 |
<0.001 |
Lactic: Acetic2 |
4.39a |
4.25a |
4.00ab |
3.88ab |
3.56b |
3.62b |
0.273 |
0.027 |
Lactic, %total |
81.4a |
80.8a |
79.9ab |
79.3ab |
77.9b |
78.0b |
1.13 |
0.019 |
Ethanol, % |
0.48a |
0.49a |
0.44a |
0.38ab |
0.33b |
0.42ab |
0.047 |
0.020 |
Ammonia, %CP |
4.09 |
4.62 |
4.40 |
4.67 |
4.69 |
5.07 |
0.324 |
0.080 |
1Not detected.
2Lactic acid-to-acetic acid ratio.
Means within a row with different superscripts differ (P ≤ 0.05).
Regression analysis indicated that moisture concentration at ensiling was a significant predictor of silage pH, lactic acid, acetic acid and total acids explaining 84%, 55%, 65% and 52%, respectively, of the variance in these attributes (Figure 1). Typical corn silage will have a pH between 3.7 and 4.2, and contain 4% to 7% lactic acid, 1% to 3% acetic acid, 1% to 3% ethanol, 5% to 7% ammonia-N and no butyric acid (Kung and Shaver 2001).
Figure 1. Effect of moisture concentration at ensiling on a) silage pH, and concentration of b) lactic acid, c) acetic acid and d) total acids.
Based on criteria for typical corn silage, ensiling corn hybrids at moisture concentrations ranging from 60% to 72% generally produced good-quality silages. Reducing variation in moisture concentration by selecting silage corn hybrids with a narrow range in relative maturity would lead to more uniform silage quality.