A single planting of a grass seed field is harvested once annually for up to 3 to 5 yr, depending on the cultivar. The harvest season extends from June through early August. High seed yield and harvest efficiency are favored by the cool, dry summer climate in the Pacific Northwest. At harvest, the grass is cut and swathed to dry for 1 wk, being turned once during this time.
When dry, the swath is picked up with a harvester, which threshes the seed and expels the straw back onto the field. The straw, yielding about 1600 kg/ha, is then gathered into larger windrows and baled (Fig. 18-1). The straw has 5 to 6% crude protein and can serve as an inexpensive source of fiber in ruminant diets (see Chapter 11). The bales of straw are collected from the field and stored in barns until compressed and repackaged for export. The bales are compressed to about one-third of their original size (Fig. 18-2). In general, compressed bales measure about 90 by 90 by 120 cm (3 by 3 by 4 ft) and weigh 318 to 363 kg (700-800 lb). Compressed bales are placed into shipment containers for export mainly to Japan, Korea, and Taiwan.
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Fig. 18-1. Tall fescue straw being gathered into windrows in preparation for
baling. (photo: Steve Van Mouwerik, Anderson Hay and Grain Co.)
Fig. 18-2. Loading harvested straw bales onto a trailer
truck. (photo: Steve Van Mouwerik, Anderson Hay and Grain Co.)
Since 1991, there have been many attempts to find uses for the straw from seed production. The most practical and economically successful use of the straw has been for animal feed. Ports in the U.S. Northwest exported more than 33,000 containers of compressed straw to Asia in 2006. In addition, Northwest cattle producers have used the straw to feed their herds. Consequently, clinical cases due to endophyte toxins in the straw have been observed and documented in recent years.
The digestion of fiber by cattle can be improved by ammoniation. Ammonia gas is piped into a stack of straw bales covered by a sealed plastic sheet. Chestnut et al. (1987) and Kallenbach et al. (2006) determined that ammoniation of E+ tall fescue straw and hay increased digestibilities of neutral detergent fiber (NDF) and acid detergent fiber (ADF) and improved the average daily gain of steers fed such straw.
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