How Stage of Maturity Affects Hay Quality - Frequently Asked Questions

 
 
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 What is “stage of maturity”?
The stage of maturity in plants is the final stage of a plant’s growth and development where plants begin to flower and then seeds are produced. The stages of maturity for grasses range from late boot to seed-set, and for legumes, early bloom to seed-set.

Why is the stage of maturity important for hay?
Plant maturity is the most significant factor affecting hay quality. About 70% of hay quality is determined by stage of maturity of plants at harvest.

What is the best stage to cut my grass or legume hay at?
The best stage to cut your hay at partly depends on the nutritional needs of the animals to be fed. For example, cows in their second trimester require lower quality hay than cows after calving. Calves with access to a low cost protein supplement require lower quality forage than calves that are only fed hay.

A second factor to consider is if you want to maximize the amount of protein harvested per acre. The best stage of maturity to accomplish this goal is at the late bud to 10% bloom stage for alfalfa, at the 10% to 20% bloom stage for clovers, and between the late boot and early heading stages for grasses. Alfalfa-grass mixtures should be cut based on the stage of maturity of the alfalfa. Clover-grass mixtures should be cut based on the stage of the grass.

Effects of Cutting Stage on Forage Quality
Stage of Maturity
% CP
% NDF
% ADF
AlfalfaEarly Bud
20.2
49.3
32.0
Late Bud
19.0
47.0
29.4
Early Bloom
17.6
52.0
31.5
TimothyJoint
11.1
68.7
38.0
Pre-bloom Head
10.2
70.6
40.4
Fully headed
7.9
72.8
40.7
Adapted from: Dr. Peiquiang Yu. When is the best cutting time for alfalfa? And When is the best cutting time for timothy hay?

What happens to forage quality if I cut later?
If you wait until your hay is more mature before cutting it, you will get higher yields. However, the material will be much lower quality.

Forage Quality of Alfalfa and Brome Hay Cut at Different Stages of Maturity
SpeciesStage of Maturity
% Crude Protein
% TDN
AlfalfaBud
21.5
63
Early Bloom
18.4
59
Mid-Bloom
15.9
55
Full-Bloom
13.5
51
BromeEarly Boot
15.0
63
Early Heading
10.5
58
Early Milk
8.0
54
Mature
6.0
48
Adapted from: NDSU. Minimizing Hay Losses and Waste. AS 1190. March 2000.

Why does forage quality change as plants mature?
As legumes and grasses move from vegetative (producing leaves) to reproductive stages (producing flowers, heads and seeds), they lose quality. This happens because the plants convert their energy from primarily producing leaves to produce flowers and seeds, resulting in stems being more present compared with leaves. Stems are higher in fibre and lower in protein than leaves.

The table below shows how the quality of four grasses grown in the Edmonton area changes as they move from vegetative to reproductive stages.

Crude Protein and Acid Detergent Fibre of Tame Grasses Cut at Weekly Intervals Starting June 1
Week
1
2
3
4
5
6
7
Brome% CP
26.2
23.4
20.3
17.8
15.4
12.3
12.4
% ADF
18.2
20.4
25.6
28.3
31.6
32.5
31.3
Crested Wheatgrass% CP
22.8
20.7
18.0
15.6
14.0
11.4
12.7
% ADF
19.6
22.6
27.0
29.9
32.3
34.9
32.5
Orchardgrass% CP
24.5
26.0
215
18.7
17.3
15.8
15.0
% ADF
16.1
22.5
25.7
27.7
29.3
29.0
27.5
Tall Fescue% CP
22.6
23.1
19.8
17.1
15.8
11.9
12.3
% ADF
16.3
21.2
24.3
26.1
27.5
30.3
26.8
Adapted from: Suleiman et al., 1995. Comparison of Yield and Quality in Prairie Grasses in One Cycle of Growth. Proc. Western Sec., Amer. Soc. An. Sci

Do leaves and stems lose quality at the same rate?
In both grasses and legumes, stems lose quality faster than leaves.
Studies have shown that there can be as much as a 50% decrease in protein in the leaves of grasses, such as smooth brome, from early growth up to maturity. The stems will lose a much greater amount of protein during the same time period. With legumes, such as alfalfa, the stems increased in fibre and lost digestibility faster than the leaves from early growth to full bloom.

Do grasses and legumes lose quality at the same rate?
Perennial grasses lose quality faster than legumes. This is because grasses completely stop producing leaves once they start to head out and flower, while legumes will keep producing leaves while flowering. Legume leaves also have higher protein levels than grass leaves on average.

Once buds start showing up on your alfalfa plants, the feeding value will decrease by about 0.2% per day in protein and 0.4% per day in digestibility. Cool-season grasses, like brome and timothy, lose 0.3-0.5% per day in digestibility after the first two to three weeks of growth.

For More Information
Alfalfa: The High Quality Hay for Horses
Forage Harvest Timing – OMAFRA
Understanding Forage Quality 		 
 
 
 
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For more information about the content of this document, contact Karin Lindquist.
This document is maintained by Kathy Andersen.
This information published to the web on July 3, 2012.
Last Reviewed/Revised on March 28, 2018.