The author is a beef cattle specialist for Texas A&M AgriLife Extension based in Overton, Texas.

A common practice for many producers during the fall is to look for the cheapest protein and energy supplements to go along with their hay for winter feeding. However, that time would be better spent during the spring and summer working to produce high-quality hay that would eliminate the need for protein and energy supplementation from grain and other concentrates.

What is high-quality hay?

To start with, I think of high-quality hay as having adequate levels of energy (calories) and crude protein to meet the nutritional requirements of the cows it will be fed to. Energy content can be reported in many ways, but for this discussion we will focus on TDN (total digestible nutrients). The table lists the amounts of crude protein and TDN required by different classes of beef cows to maintain body weight under typical production conditions.

Mineral concentration, palatability, and absence of toxic compounds are also important when evaluating hay quality. Also consider factors related to storage losses such as bale size, bale shape, bale density, and forage species.

Many people focus solely on the crude protein concentration, but this is a bad approach. Consider both crude protein and TDN when evaluating hay because high crude protein content does not always correspond to a high TDN content. Additionally, it is often more expensive and labor intensive to provide energy supplementation than protein supplementation.

From the values in the table, we could set a goal of producing hay that is at least 12 percent crude protein and 62 to 63 percent TDN. This would cover the needs of most lactating cows and eliminate the need for protein and energy supplementation. As many producers know, achieving higher crude protein levels with bermudagrass is relatively simple. However, achieving high TDN levels is more challenging. Various agronomic and environmental factors influence TDN content in hay and understanding some key ones will help us meet our goal.

Know the factors

Plant maturity is one of the biggest factors affecting forage digestibility and thus TDN concentration. As plants advance in maturity, lignin and fiber (plant structural components) concentrations elevate, which cause a decline in both TDN and crude protein. To optimize both forage quality and yield, harvest bermudagrass and similar forages every three to five weeks; sudangrass, sorghum-sudangrass hybrids, and other similar forages should be harvested before the production of a mature seedhead.

Proper fertilization can enhance the growth of bermudagrass and other forages allowing hay to be harvested at shorter intervals, which will improve TDN concentration. Additionally, higher nitrogen fertilization rates can boost crude protein content. Research with bermudagrass indicates that the production of an additional 15 to 40 pounds of forage per acre is realized for each pound of nitrogen fertilizer applied.

Ammonium nitrate that costs $350 per ton translates to 51 cents per pound of nitrogen. When compared to traditional supplements, an application of nitrogen fertilizer is a great investment. Not all grasses respond equally to fertilization, so visit with an extension specialist or agronomist about the potential return on investment for other forage species.

Temperature also has a major impact on nutritional value of many introduced warm-season grasses. As the temperature rises, lignin deposition in the plant accelerates, which in turn lowers forage digestibility. Because of this relationship, hay harvested in the spring and fall will typically have a higher TDN concentration than hay harvested during midsummer.

Rain during harvest will also affect hay quality. If hay is rained on after cutting but before baling, an increase in crude protein concentration and a decline in TDN concentration is generally observed. This happens because some of the soluble carbohydrates and minerals are washed out of the hay, thereby raising the concentration of the remaining components such as crude protein. This is a perfect example of why it is important to analyze for both crude protein and TDN. If the hay receives several inches of rain while in the windrow, both the crude protein and TDN will decline.

Instead of focusing just on the tons of hay produced this year, consider how managing for quality can eliminate your winter protein and energy supplementation needs. Giving up a little yield to produce better quality hay that meets the requirements of your cows can save money and reduce the labor needed for winter feeding.

Even if you are going to feed all the hay you produce, it is important to test each cutting so that the best hay can be fed to the cows with the highest requirements and other hay can be used when nutrient demands are less. Before sending samples to the lab, visit with a nutritionist for lab recommendations and the appropriate tests for your hay sample.

This article appeared in the April/May 2017 issue of Hay & Forage Grower on page 34.

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