Extension > Agriculture > Dairy Extension > Forages > Quality assessments of alfalfa/grass mixtures
Quality assessments of alfalfa/grass mixtures
Published in Dairy Star November 5, 2010
In an earlier article (August 28, 2010, by Paul Peterson), data showing forage dry matter yields and grass content was presented for ongoing alfalfa/grass mixture plot work for two locations in Minnesota–Hutchinson and Underwood. The article, Alfalfa/Grass mixtures look promising on MN farms, is available on the Dairy Extension website. Presented in Tables 1 and 2 are data for quality assessments of the forage mixtures harvested for three cuttings in 2010 at these locations.
There are considerable differences between locations for the amount of grass in the plots. By visual assessment, Underwood plots averaged 29 percent grass while Hutchinson averaged just 11 percent. Tables 1 and 2 are set up in descending order of dry matter yield at the Underwood location. At the Hutchinson location, orchard grass was the highest yielder followed by tall fescue, meadow fescue, meadow brome, perennial rye grass, reed canary grass, smooth brome, alfalfa alone, and lastly timothy as in Underwood. Yields through four cuttings averaged 5.9 ton DM per acre at Underwood and 4.8 ton DM per acre at Hutchinson. Quality data on fourth cut harvest is not available at this time.
Examining the data, we observe several things. First, there are greater differences between cuttings than between locations within cutting. The predominant forage was alfalfa in both locations. The amount of grass in the mixtures was higher at Underwood than at Hutchinson. In each cutting and location and between locations, values for crude protein and NDF were similar. A greater effect is shown between locations for first harvest, which may be due more to cutting date than location. Also noteworthy is the decline in CP, NDF, and RFQ with each successive cutting. This is likely due to the increasing temperatures of the growing season, which has a negative correlation to forage quality, especially with cool season grasses as were used in these plots. It may also be an effect of days between cuttings, which reinforces the importance of a timely first cutting and a set schedule for harvesting later cuttings.
The reasons for including grasses in a forage program are to increase the amount of digestible NDF in the forage of the diet while adding effective fiber and more rumen mat. Grasses will also help forage dry faster, utilize nitrogen from the alfalfa, and add to yield potential. Data thus far would indicate that mixed stands of alfalfa and cool season grasses can compete with alfalfa alone for yield and quality.
Table 1. Average Quality Assessments of Forage Mixtures at Hutchinson, 2010. |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
Forage Type |
1st Harvest |
2nd Harvest |
3rd Harvest |
||||||
CP |
NDF |
RFQ |
CP |
NDF |
RFQ |
CP |
NDF |
RFQ |
|
TF |
22.3 |
41.7 |
158 |
19.0 |
46.3 |
126 |
19.4 |
47.1 |
126 |
None |
21.9 |
43.1 |
144 |
19.9 |
45.1 |
127 |
20.0 |
45.9 |
125 |
MF |
20.2 |
44.9 |
145 |
18.4 |
48.7 |
121 |
19.1 |
49.9 |
114 |
RCG |
20.9 |
44.6 |
137 |
20.1 |
43.9 |
133 |
19.9 |
45.8 |
124 |
MB |
21.3 |
43.9 |
143 |
19.9 |
45.4 |
127 |
20.2 |
46.5 |
124 |
OG |
19.2 |
49.8 |
126 |
17.6 |
51.0 |
120 |
18.9 |
51.2 |
119 |
PRG |
21.2 |
43.2 |
148 |
18.5 |
49.1 |
114 |
19.0 |
49.2 |
118 |
SB |
22.4 |
41.2 |
152 |
20.0 |
45.2 |
127 |
20.5 |
44.6 |
135 |
TIM |
20.0 |
47.9 |
132 |
20.2 |
44.2 |
135 |
19.8 |
47.7 |
121 |
Table 2. Average Quality Assessments of Forage Mixtures at Underwood, 2010. |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
Forage Type |
1st Harvest |
2nd Harvest |
3rd Harvest |
||||||
CP |
NDF |
RFQ |
CP |
NDF |
RFQ |
CP |
NDF |
RFQ |
|
TF |
21.7 |
44.2 |
150 |
18.9 |
47.8 |
130 |
17.1 |
52.6 |
101 |
None |
22.3 |
44.6 |
138 |
20.1 |
43.8 |
123 |
18.0 |
50.9 |
108 |
MF |
22.8 |
43.4 |
157 |
18.7 |
47.7 |
143 |
17.2 |
50.1 |
124 |
RCG |
22.9 |
42.8 |
151 |
20.7 |
43.2 |
135 |
18.4 |
48.5 |
105 |
MB |
22.4 |
44.5 |
144 |
20.9 |
44.1 |
138 |
18.0 |
52.0 |
99.5 |
OG |
22.5 |
44.6 |
154 |
17.8 |
50.2 |
132 |
17.9 |
50.8 |
117 |
PRG |
22.2 |
44.2 |
140 |
21.7 |
41.5 |
136 |
18.4 |
48.2 |
105 |
SB |
22.4 |
47.1 |
130 |
20.3 |
46.9 |
125 |
18.1 |
51.0 |
98 |
TIM |
21.7 |
45.4 |
152 |
18.2 |
47.9 |
129 |
19.0 |
49.0 |
113 |
Key: TF: tall fescue; MF: meadow fescue; RCG: reed canary grass; MB: meadow brome; OG: orchard grass; PRG: perennial rye grass; SB: smooth brome; TIM: timothy; none: pure alfalfa; CP: crude protein; NDF: neutral detergent fiber; RFQ: relative forage quality.
