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Big Bluestem for High Quality Summer Forage

Dwight Tober, USDA-NRCS Plant Materials Specialist, Bismarck, ND
Paul Nyren, and Brian Kreft, NDSU Central Grasslands Research Extension Center, Streeter, ND


Most livestock producers already have adequate cool-season pasture for early and late season grazing. What about mid-summer? Northern adapted varieties of big bluestem are now available for use in summer grazing. The variety Bison big bluestem originates from central North Dakota and can provide large quantities of high quality forage in July and August when cool-season species such as bromegrass and intermediate wheatgrass go through summer dormancy and rapid decline in digestibility and crude protein. Recent studies conducted at the Hettinger Research Experiment Center have shown Bison big bluestem to test 13.3% crude protein and 72% dry matter digestibility in late June. Peak oven dried forage production was almost 6,000 pounds per acre. A comparable study at Hettinger showed Oahe intermediate wheatgrass at the same time to test 6.9% crude protein and 59% dry matter digestibility. Peak oven dry forage production was 2,733 pounds per acre. Warm-season grasses such as big bluestem start growing at temperatures near 55 degrees F. and grow best at temperatures of 80-90 degrees F. in mid-summer. Including warm-season grasses in a grazing system allows cool-season grasses a rest period in mid-summer which improves their vigor and enhances forage production for late summer and fall.


Mature big bluestem is 3 to 6 feet tall with coarse stems and abundant leaves. Big bluestem is considered an ice cream plant to livestock and if given the opportunity, livestock will graze the plants to ground level. Producers desiring high quality forage should harvest at boot stage (immediately before seedheads emerge) and graze to a 6-inch stubble height. Stocking density should be high enough to use most of the grasses before the stems develop. Rotational grazing is recommended to reduce trampling and enhance utilization. Harvest at heading will often result in greater yields but forage quality will be lower. For hay production, big bluestem should be harvested at boot stage and leaving a 6-inch stubble.


In 1994 a 30 acre pasture was seeded to Bison big bluestem at the CGREC. The pasture was seeded on May 19th using seven pounds/acre PLS with a Truax native grass drill from the NRCS Plant Materials Center. The pasture was hayed to remove the cover of weeds in the summer of 1994 and was hayed or grazed from 1995-1998. In 1999 the stand produced a good seed set so the pasture was swathed and the seed harvested with the help of the NRCS Plant Materials Center staff. The pasture was hayed in 2000 and in 2001 it was grazed with 19 cow-calf pairs. The animals were put on the pasture on the 9th of August and removed on the 19th of September for a 41 day grazing period. This calculates to 1.15 acres per animal unit month. The cows averaged 1412 on Aug. 9 and weighed 1380 on Sept. 19 for an average loss of 0.80 lbs per head per day. The calves beginning average weight was 385 lbs and their ending weight was 498 lbs for a average daily gain of 2.75 lbs/head/day. The starting date of the study was delayed pending the availability of livestock but should have been started several weeks earlier. While the calves performed well on the study the animals clearly found the forage less palatable than they would have earlier in the season (Table 1).


Three varieties of big bluestem are recommended for North Dakota. Bison (central ND origin) has the earliest maturity. Bonilla (east central SD origin) is about 2 weeks later than Bison, and Sunnyview (southeast SD origin) is about three weeks later than Bison. Sunnyview generally produces the most forage. Seed prices have recently lowered for big bluestem and are in the $5 to $7 dollar range for pure live seeds(PLS)/pound. Certified seed is recommended and often does not cost anymore than noncertified. The seeding rate is 6 PLS pounds per acre in the western part of North Dakota or on drier sites, and 7.5 PLS pounds per acre in the eastern part of the state or on sites with more favorable moisture conditions. Big bluestem performs best on silt and silt loam soils and with favorable management excellent stands can be maintained for 20 years or more. Seed prices are down for big bluestem! Now is the time to establish a high quality forage base of big bluestem for mid-summer grazing!

 

Table 1. Livestock performance on the big bluestem pastures at CGREC in 2001.

 

Beginning Weight (lb)

Ending
Weight (lb)

Average Daily Gain
(lb)

Cow 

1412

1380

-0.80

Calves

385

498

2.75

Cow Condition Score: 5.2

Stocking Rate: 1.15 Acre/Animal Unit Month

Grazing Season Length: August 9 to September 19 (41 days)

 


  
NDSU Central Grasslands Research Extension Center
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