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Weathering weather: Forage quality in ‘abnormal’ years

K.E. Lanka, David Jones and Gene P. Gengelbach Published on 14 August 2013
Cut hay

It seems as though the weather this year is abnormal. But then, so was last year, as were several previous years.

Because forage quality is important, a review of temperature and precipitation conditions can help maintain focus on considerations for feeding livestock in spite of variations in weather.

Wet weather effects
Wet weather during harvest creates several forage problems, including less control of harvest timing due to wet fields.

Hay harvested in wet weather is generally better suited to haylage than to baled hay. However, haylage harvested in wet weather can also have higher stem lignin, reducing overall quality. It’s also more likely to contain clostridia – butyric acid.

Wet weather also promotes lower leaf-to-stem ratio due to rapid plant growth and reduces forage digestibility. What does this mean at feedout? Feeders may need to increase grain in the ration.

Management considerations in wet weather
For best quality, forages should be harvested at peak quality rather than by date or the calendar. When fields are wet, this is more difficult to do. If the temperature is warm, the window for best feeding value and drying time may be limited. Conditioning the forage can speed up drying time.

Silages harvested after rainy weather are more likely to have clostridia due to dirt that is splashed by the rain or picked up by chopper teeth. In addition, wet haylage or baleage promotes clostridial growth during the ensiling process.

Crimping and wide swathing of the forage will speed up the drying process for hay, baleage or silages. If rain is in the forecast after the forage is cut, an option is to make baleage or haylage instead of hay.

Sugars and carbohydrates may be lost due to rain leaching from forages. In addition, there continues to be respiration by the plants after cutting. This will reduce the energy in the finished forage and increase the indigestible fiber.

Cold weather effects
Colder growing seasons produce lower tonnage per acre, and forages require longer drying times. The good news is that colder weather promotes higher leaf-to-stem ratio due to slow plant growth.

This results in a higher quality of haylage due to lower stem lignin. Forage digestibility is also increased. What does this mean at feedout? Feeders may need to reduce the need for grain in the ration, if there is adequate supply of the forage.

Management considerations in cold weather
During cold seasons, forages grow more slowly. For alfalfa, this will yield higher leaf-to-stem ratios. Slower-growing forages normally have more protein, more energy and better rumen digestibility than during hot weather, when the plants have more stems and greater lignin.

Even though tonnage per acre is lower in cold weather, when fed to dairy animals the amount of milk that is supported by the forage is favorable, and less is needed to meet the needs of the animal. This is often the case with cold-spring forages and late-fall alfalfa.

Cold weather is not favorable for rapid drying after cutting. Thus, wide swathing and well-maintained crimper rollers can help in faster drydown and better quality of the end product.

Dry weather effects
Dry-weather growing seasons produce lower forage tonnage per acre; however, forages dry faster. Higher leaf-to-stem ratios occur during dry weather due to slow plant growth. Forage quality ultimately varies, depending on temperature while growing.

The benefit of forage grown in dry weather is that higher leaf-to-stem ratios occur due to slow plant growth, and when harvested it dries faster in the field.

Dry weather also allows harvesting forages when they’re ready. Dry weather and drought conditions bring lower lignin production, which makes fiber more digestible in corn silage.

Management considerations in dry weather
Dry weather can be beneficial in getting good-quality forages. Drought conditions can severely reduce the tonnage per acre, especially for corn plants that do not pollinate well or do not develop ears. However, even drought-stressed corn silage and other forages will enhance milkfat due to lower lignin in the slow-growing plants.

Dry conditions allow forage growers to get into the field when it is ready to harvest. This should be taken advantage of to cut fields at peak quality. A few days of delay can make a large difference in the feeding value of forages.

Plants dry more quickly during dry weather and low humidity. It is important to carefully check the fields to ensure that the forages do not get too dry. This is especially true when making alfalfa hay, when leaves can be lost and left in the field.

Leaves are the most concentrated source of nutrients in the plant. Leaf loss greatly diminishes the feeding value of hay or baleage.

Hot weather effects
Hot weather can work for you or against you, depending on the moisture available. With adequate rain or irrigation, hot weather increases tonnage per acre. During hot weather, forages dry rapidly as well.

Hot weather promotes lower leaf-to-stem ratio due to fast plant growth; hence, haylage quality is lower due to higher stem lignin. This reduces forage digestibility and feeders may consider increasing the need for grain in the feedout ration.

Management considerations in hot weather
The principles of making forages during hot weather are much like those of dry weather. However, making quality forages during hot, wet weather offers the greatest challenges with respect to quality.

Forages dry much faster in hot weather than in cool weather, and the formation of lignin is a rapid process as the plant continues to breathe after being cut. As a result, careful management and harvesting decisions need to be made to maintain the best possible quality.

During drought years, decisions may need to be made sooner than usual to even salvage the forages. This was the case with chopping corn silage in some regions of the country during the summer of 2012.

Hot temperatures can also cause summer thunderstorms. Knowing the forecast will help to reduce weather-damaged forages due to sudden rains after forages are cut.

Getting the most from forage
Weather is often reported, in magazines and official reports, in comparison to average or normal years. However, each year and month is different from the others. Planting, growing, harvesting and storing decisions must be made with respect to what is happening now and what is expected in the near future.

Decisions need to be made for how to produce and keep the best-quality forages.

Economics of feeding local forages is more important than ever as competition grows for outside hays, baleages, silages, grains and protein supplements.

Weather and climate have a large impact on how decisions are made to produce high-quality feed.

Whatever the season, decisions must be made for planting, growing, harvesting and storing forages for optimal production. Though some years may vary more than others from the average, there really is no “normal” year.  

Weather is often reported, in magazines and official reports, in comparison to average or normal years. However, each year and month is different from the others. Planting, growing, harvesting and storing decisions must be made with respect to what is happening now and what is expected in the near future. Photo by Bill Paul.


K.E. Lanka
Dairy Nutritionist
Agri-King, Inc.