Farm Progress

Hay quality factors

Jeffrey Stapper

May 14, 2010

5 Min Read

The early wet spring has allowed some South Texas growers to make hay in the last few weeks, so now they should consider factors that influence hay quality.

Hay varies in quality more than any other harvested feed crop. Quality can vary widely, even when composed of the same species, when grown in the same vicinity, and when grown and cured under similar conditions. Moreover, hay can look good with a dark green color, and still be low in quality, or can look bad, without a good dark green color, and still be good quality. The best way to determine hay quality is to have it tested by a forage testing lab.

Factors that determine hay quality include stages of maturity at harvest, soil fertility, nutritional status of the plant, available moisture during the growing season, season of the year, ratio of leaves to stems and stem size, weed control, foreign matter, harvesting, weather at harvest and storage.

Of all the factors that influence quality, stage of maturity or age of the plant at harvest is the most important. In fact, about 70 percent of the quality of hay is determined by stage of maturity at harvest. As a forage plant matures toward heading—from flowering to seed formation—the growth pattern changes from leaf production to hard stem formation.

Since leaves are more digestible than stems and contain most of the nutrients, the higher the leaf content, the higher the quality. Furthermore, the younger the plant, the greater is the proportion of leaves, thus a higher quality plant. A quick visual method to determine maturity can be done by looking for seed heads. As a simple guide, grass hays with only a few immature seed heads are generally a higher quality, and as the number and amount of mature seed in the heads increase, the quality decreases.

Soil fertility is also an important factor in determining the ultimate quality of hay. Nitrogen fertility rates for grasses greatly influence the crude protein levels in forages harvested at the right stage of maturity. The nitrogen content of a forage crop is a direct measure of its protein content. The nitrogen that is extracted from forage is multiplied by a factor of 6.25 and reported as percent crude protein. Thus, a forage containing 2 percent nitrogen contains 12.50 percent crude protein. Phosphorus, potassium and other nutrients are also critical to maintaining stands and producing quality hay. A soil test should be taken once a year to determine the amount of plant nutrients remaining after last year’s hay crop to replace those elements removed by harvest.

So when is the best time to make hay? The proper stage of growth for harvesting forages is when the greatest amount of total digestible nutrients per acre may be obtained. This usually represents the best compromise between quality and yield. Generally, the younger the crop is at the time of harvest, the higher the quality but the lower the yield will be. The more mature the crop at time of harvest, the higher the yield but the lower the quality.

Research also indicates that forages are higher in quality during spring and fall and lower in quality during mid-summer. Recent experiments (USDA) indicate that cattle prefer afternoon cut hay over morning cut hay. Since cells make sugars and carbohydrates in the presence of sunlight, afternoon cut hay may contain a higher percentage of highly digestible sugars and carbohydrates. Plants cut in the morning have partially depleted the supply while respiring or using energy through the night.

Color is not always a good indicator of quality, as it usually is a good indicator of the curing process following cutting. Bright green hay usually means the hay was cut at a desirable stage of maturity and cured rapidly. The yellow color often seen is a sign of significant amount of sun bleaching, but quality not seriously reduced. Brown colored hay usually indicates excessive moisture fell on the hay during the curing process, and the hay usually has a musty odor. Odor can be an indicator of reduced quality. Hay with off odors like mildew, mustiness or a rotten smell can be an indicator of reduced quality and poor acceptance by livestock.

The goal of harvesting should be to maintain the highest nutritive quality as possible through cutting at the proper stage of maturity, promoting rapid dry down, maintaining high leaf content and timely baling at the right moisture content. Bacteria and fungi that cause hay to deteriorate need moisture to grow. If hay is baled at too high moisture, bale heating occurs shortly after harvest. Microbes are not able to reproduce if moisture levels are below about 14 percent.

Small 60 to 70 pound bales can be baled at 16percent to 18 percent moisture while hay stored in large round bales should be dryer (14percent to 16 percent) at baling since moisture can’t escape from the center of a large bale.

Foreign matter also can affect hay quality. Weeds are the biggest problem, and sometimes even injurious materials like three-awn grass seedheads, sandburs, and toxic plants can be found. When buying hay, always look for foreign matter.

Finally, soft, pliable hays are usually more palatable than hard, firm hays, as this usually indicates the lack of lignin or stem maturity.

More information on hay quality can be found at

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