The standing dry matter of stockpiled tall fescue decreases over winter. Amounts of dry matter loss vary (Fribourg and Bell, 1984; Matches, 1979; Rayburn et al., 1979) and typically may amount to 25%. This dry matter loss is independent of N rate and stockpile initiation date (Collins and Balasko, 1981a).
As stockpiled tall fescue overwinters, it loses forage quality. In general, stockpiled tall fescue loses soluble carbohydrates, possibly due to leaching from cells damaged by frost. The loss in carbohydrates is accompanied by an increase in fiber concentration and a decrease in digestibility. Some of the mineral constituents also are lost over winter, with K being the most frequently reported lost component (Collins and Balasko, 1981b; Fribourg and Bell, 1984). However, the drop in forage quality of tall fescue during winter is much less than that which occurs with other stockpiled forage crops.
In addition to the loss of nutritional constituents over the winter, tall fescue also appears to lose most of its ergovaline, one of the alkaloids (see Chapter 13) implied in tall fescue toxicosis (see Chapter 12). In Missouri, Kallenbach et al. (2003) reported that the ergovaline content of E+ ‘Kentucky 31' (KY-31) tall fescue decreased 85% from October to March.
The best way to utilize stockpiled tall fescue is by strip-grazing, a form of limit feeding, whereby cattle are allowed to graze the pasture progressively, one strip at a time. Strip-grazing allows managers to allocate feed required for livestock maintenance over the winter and also prevents trampling of the ungrazed stockpiled forage.
In winter and early spring, cattle grazing E+ tall fescue should be monitored for "fescue foot" (see Chapter 16 and Chapter 18). This disorder, caused by vasoconstriction, prevents normal blood flow to the extremities and, if allowed to follow its course, may lead to loss of hooves and tail, thereby forcing euthanasia of the affected animals. Vasoconstriction is associated with the ergot alkaloids in E+ tall fescue, which can increase in concentration with high rates of N fertilizer.
In late autumn and throughout the winter, grazing livestock, such as pregnant dry beef cows, may require P and Mg mineral supplements because of the mineral losses that occur from late autumn through the winter in cattle (Collins and Balasko, 1981b). The P and Mg, as well as a number of other nutrients essential for cattle nutrition, can be supplied with salt blocks fortified with minerals.
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