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How does tedding affect alfalfa silage production?

Quick facts 

  • Tedding can be a useful tool to increase drying rate and preserve the concentration of important nutrients in alfalfa silage. Tedding is the process of lifting and spreading out mowed hay.

  • Tedding adds cost to production. To determine financial feasibility, use the Plug in Decision Tool for Tedding Costs.

  • Alfalfa is an important forage to livestock owners and can be fed as pasture, hay or silage. Silage is popular because it is more resistant to spoilage and requires less drying time compared to alfalfa harvested for hay.

Mown alfalfa

How does tedding affect drying rate and quality?

The practice of tedding can increase drying rate but comes with a cost of added time, expenses and equipment. Additionally, tedding may impact quality as this is an added handling step in harvesting.

Research found tedding increased drying rate, resulting in a lower harvest moisture at all cuttings. Nutritional quality was also affected with the exception of total digestible nutrients (TDN); see table 1. At all cuttings, crude protein (CP) decreased by tedding and water-soluble carbohydrates (WSC) increased.

Table 1. Composition of tedded and un-tedded treatments averaged across each cutting of the field study

Cutting Treatment Harvest moisture content, % wet basis1 CP, %, dry matter1 Neutral detergent fiber (NDF), % dry matter1 WSC, % dry matter1 Ash, % dry matter1 TDN, % dry matter1
1 Un-tedded 69a 21.9a 41.1 5.4a 10.5 65.9
1 Tedded 58b 21.4b 41.3 6.2b 10.6 66.1
2 Un-tedded 65a 20.9a 42.4 5.2a 11.7a 64.5
2 Tedded 49b 20.4b 42.0 6.3b 10.7b 64.7
3 Un-tedded 521 22.3a 32.7a 8.9a 10.8a 67.3
3 Tedded 47b 21.5b 35.1b 9.5b 9.4b 67.0

1Columns within each cutting with different superscripts are statistically different (P≤0.05).

Tedding alfalfa
Tedding alfalfa
  • Water soluble carbohydrates are, as the name implies, water soluble. Therefore, the longer a forage takes to dry (or is allowed to dry), the more WSCs are lost.

    • Tedding appears to help preserve WSC by speeding the rate of drying.

  • Neutral detergent fiber was different at the third cutting only and was increased by tedding.

    • Due to NDF being a structural fiber that accumulates in the plant with growth, it is unlikely that fermentation would generate more indigestible fiber. Therefore, changes in NDF most likely reflect leaching of other nutritional components, for example WSC, resulting in a concentration of NDF.

  • Ash was reduced in the tedding treatment for the second and third cuts. Ash content may have been impacted by the weight of the swaths as the un-tedded regions were heavier and had more contact with the soil when drying, potentially picking up more ash material from the soil.

Water-soluble carbohydrates and fermentation

Mown alfalfa

Silage is created by harvesting, processing, and storing forage, or grain crops, in a way that allows for fermentation. When creating silage, it is important to harvest so that both yield and quality are maximized, but this can be challenging as they are influenced by multiple factors. Effects of plant drying and weather damage are closely related. On the other hand, if allowed to dry too much, fermentation is not achieved, and leaf shatter — or loss — may occur and result in the loss of valuable plant material.

In order for fermentation to occur successfully, an ideal WSC concentration and moisture level must be met. In the event that WSC concentration is below optimal levels, additives can increase total WSC concentration.

Legumes, such as alfalfa, can be tricky in regard to WSC as they have a high buffering capacity, meaning that they are resistant to pH changes that are necessary for fermentation; therefore, they require higher WSC levels compared to grasses for successful fermentation.

See figure 1 for ideal WSC concentrations. In this study, WSC were below optimal levels for alfalfa silage production for both treatments in the first cut, but in the second cutting, tedding increased WSC to the optimal range, and in the third cutting, both harvest methods produced optimal WSC concentrations.

Figure 1. Water-soluble carbohydrate concentration required for fermentation of alfalfa in silage production (adapted from Pitt, 1990 and Romero et al., 2015).

Minimum initial water soluble carbohydrates graph that shows lower dry matter percentage is associated with higher minimum initial water soluble carbohydrates.

The practice of tedding can be used to increase drying rate, but comes with a cost of added time, additional expenses and equipment. Additionally, tedding may impact quality as this is an added handling step in the harvesting processes. However, tedding can be a positive impact by increasing WSC or a negative one by reducing CP, likely caused from leaf loss.

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Aubrey Jaqueth, post-doctoral associate, College of Food, Agriculture and Natural Resource Sciences; Krishona Martinson, Extension equine specialist; Lindsey Murry, undergraduate research assistant, University of Wisconsin -River Falls; Matthew Digman, assistant professor of Agricultural Engineering Technology, University of Wisconsin

Acknowledgments

Funding for this study was provided by the U.S. Alfalfa Farmer Research Initiative of the National Alfalfa & Forage Alliance.

Reviewed in 2019

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