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Pasture Forage for Dairy Cattle1
Barney Harris, Jr.2Grazing dairy cattle on pasture grasses and legumes is a common practice in many areas of the country. Forages (hay, pasture, and silage) play a vital role in meeting the nutrient requirements of dairy cattle and many dairymen may use all three forms of forages.
The quality of pasture or green chop forage varies considerably throughout the year. This variation in quality becomes exceedingly important where large quantities of forages are fed. The contribution that pasture forages can make in meeting the nutrient requirements for high producers is affected by both the quality and quantity of forage. Care must be taken to avoid overestimating both the quality and quantity of forage intake or underfeeding may result, causing a drop in milk production.
NUTRIENT VALUE OF PASTURE
A laboratory analysis is useful in determining the nutrient value of stored feeds. The use of green forages, however, presents a different problem since quality varies with maturity and some plants mature at a rapid rate. Even so, with good knowledge and an accumulation of data from forages being analyzed, the nutrient content of the forage can be estimated fairly close to the real value. The values in Table 1 are averages accumulated from Florida forages which were tested in laboratories.The protein content of forages is easily influenced by the level of fertilization. For this reason, one can anticipate some variation in the protein content as compared to the average figures given in the above table.
QUANTITY OF PASTURE CONSUMED
After one has arrived at a realistic figure to place on the quality of the forage, the quantity to be fed becomes the next important step. If the forage is green chopped and fed in a bunk, the amount fed per cow can be calculated. Generally, this can be accomplished by either weighing the wagon, estimating the amount on the wagon, or weighing short sections of the forage placed in the bunk and calculating the amount available per cow. In order to have a good feeding program, the dairyman needs to know the average forage consumed per cow. Too many dairymen ignore this part of their feeding program.Pasture consumption from grazing may be more difficult to estimate (Table 2 ). Generally, for high producers receiving grain, consumption will vary from 30 lb to 100 lb per cow per day. The wide variation in consumption is due to pasture quality and the quantity available. Also, season of the year has a great influence on pasture consumption. During the hot summer months, pasture consumption may drop 25 to 40%.
The consumption values in Table 2 may be obtained where cows are allowed to graze for one to two hours per day. Cows will obtain their greatest consumption in the first 30 minutes of grazing; by the end of one hour, they will have a good fill. Cows remaining on winter or summer annual grasses beyond one hour will cause danger to the plants by trampling.
Dairy cows will usually remain on permanent pastures such as bahia, bermuda, and pangola for longer periods.
After establishing an estimated value for the quality and quantity of pasture or green chop being consumed, the formulation may be completed through computer usage or extensive hand calculations.
Tables
Table 1. A summary of the results obtained in the forage testing program in Tallahassee, FL -- hay, silage, and green chop (as fed).
Crude
DM
CP
fiber
TDN
NEL
Sample Name
Number
(%)
(%)
(%)
(%)
(Mcal)
A. HAY
Aeschynoneme 8
87.9
11.5
30.8
43.0
31.5
Alfalfa 32
90.8
16.0
25.8
54.2
45.6
Bahia Argentina
61
91.5
7.0
28.0
45.4
33.4
Pensacola
24
91.0
5.8
28.0
43.5
32.0
Bermuda Alicia
56
90.6
8.6
29.2
44.8
33.2
Callie
58
91.4
9.4
30.7
46.5
35.0
Coastal
417
92.0
8.2
21.5
48.0
40.0
Coastcross
59
90.0
7.8
31.0
45.4
34.2
Unspecified
61
91.0
9.1
29.8
42.5
31.0
Bluestem 45
92.0
4.9
30.0
44.1
32.0
Clover Alyce
49
90.4
11.1
35.6
44.5
31.0
Ladino
2
92.4
7.8
33.0
45.8
32.0
White
2
90.0
11.0
35.8
43.8
30.1
Carpetgrass 7
91.5
6.2
26.6
47.2
36.1
Crabgrass 8
91.8
4.2
32.0
40.0
29.0
Elephant grass (dwarf) 2
90.2
10.8
29.5
58.0
48.0
Hairy Indigo 7
90.0
9.5
36.8
36.0
24.6
Hemarthria Altissima 10
90.0
6.8
32.5
42.6
30.1
Indiangrass 43
91.2
4.6
31.5
45.2
32.5
Maidencane 62
92.1
8.0
30.0
48.5
36.0
Millet 7
91.0
7.2
30.1
46.5
35.1
Oats 23
90.0
7.2
28.0
41.0
38.0
Pangola 166
91.8
5.0
29.9
41.6
29.5
Peanut, forage 6
92.0
8.2
38.3
40.0
31.6
Peanut, Perennial 12
92.0
13.0
24.0
54.0
44.0
Peavine 5
91.4
6.7
39.2
39.0
31.0
Rye 6
92.3
8.2
32.0
47.6
34.4
Ryegrass 8
91.0
9.0
28.0
52.6
40.6
Sorghum Sudan (Sudex) 4
91.0
5.4
32.8
46.2
32.7
Soybean 7
91.0
8.8
33.5
45.1
31.6
Stargrass 8
91.4
7.3
29.1
53.7
43.4
Torpedo 6
91.0
5.5
30.5
47.6
34.6
B. AVERAGE SILAGE ANALYSIS
Corn 170
28.0
2.4
7.0
19.1
16.4
Bermuda Callie
15
35.0
2.9
10.1
19.9
15.7
Coastal
5
34.0
2.7
11.3
18.1
14.0
Hermathria 5
31.0
1.2
9.1
17.8
14.0
Millet 7
24.0
1.5
8.4
11.8
9.0
Pangola 13
27.0
2.2
10.0
12.8
9.2
Small Grain Oat
6
31.0
2.6
11.0
18.0
16.0
Rye
4
30.0
2.8
9.7
17.2
13.4
Sorghum, forage 20
28.0
2.1
8.0
15.0
13.5
Sorghum, grain 64
28.0
2.3
7.6
17.0
15.0
Sorghum, Sudan (Sudex) 28
23.0
2.7
7.6
13.0
10.0
C. AVERAGE GREEN CHOP ANALYSIS
Aeschynoneme 4
31.2
5.1
12.1
14.5
13.0
Alfalfa 4
18.0
3.6
5.7
9.1
7.0
Hermathria grass 14
29.0
2.5
9.1
15.4
11.6
Bahia 6
25.0
2.6
7.3
14.6
12.0
Bermuda 7
27.0
4.0
9.0
15.0
12.0
Elephant grass (dwarf) 2
20.0
2.4
8.0
12.5
10.6
Maidencane 11
35.0
3.0
12.9
16.0
14.0
Millet 2
15.0
1.5
4.7
7.6
5.8
Rye 3
20.0
3.0
5.1
12.8
11.0
Sorghum Sudan 2
20.2
1.5
6.7
10.2
7.5
Torpedo 2
34.0
4.0
10.3
17.2
15.4
Wheat 2
26.0
3.3
6.8
18.0
16.5
Table 2. Estimated pasture consumption per day (as fed).
Pasture Condition
Pasture Forage
Excellent*
(lbs)
Good**
(lbs)
Fair***
(lbs)
Scanty****
(lbs)
Bahia 70
50
30
20
Bermuda 75
60
35
25
Clovers 90
70
45
30
Millet 90
70
50
30
Oats 90
70
50
30
Rye 90
70
50
30
Pangola 75
60
35
20
Ryegrass 90
65
40
25
Sudex 90
70
50
30
*A pasture furnishing an abundance of lush, actively palatable forage.
Footnotes
1. This document is DS42, one of a series of the Animal Science Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 1992. Reviewed June 2003. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.2. Professor, Dairy Science Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
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