Alfalfa Harvest: What's Causing Disappointing Test Weights

Alfalfa Harvest: What's Causing Disappointing Test Weights

July 25, 2008

With the late start, cooler temperatures and increased rain, a number of crop production factors are a little different this year, including pasture production and hay content.

For instance, it's not unusual for calf weaning weights and replacement heifer rates of gain to be higher in dry years than in wet years - as long as it wasn't so dry that animals went hungry. Even though the grass is lush and looks excellent, in wet years it also contains more moisture and can be what some people might call "washy." The extra growth that was stimulated by all the moisture tends to dilute the nutrient concentration in the grass. Plus, it tends to pass through the animals more rapidly so some nutrients don't get digested.

Low forage test values for alfalfa hay this spring also may have been caused partly by this dilution effect. as well as several other factors.

Factors Affecting Alfalfa Nutrient Value

One factor might have been that the alfalfa was simply cut later than usual due to all the rain delays. It may not have looked more mature, but it still was older and thus contained extra fiber.

Another issue is slow drying of hay after cutting due to high humidity or cloudy weather. Until alfalfa dries down to less than 50% moisture, it continues to burn off nutrients. When it takes alfalfa longer to dry down, more desirable nutrients are burned away, leaving behind the less desirable fiber. Plus, cloudy weather reduces the amount of nutrients originallyproduced.

Every year is different — some more than others — so be prepared to adjust your cattle grazing and feed plans accordingly.

Bruce Anderson
Extension Forage Specialist

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