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Title: Intake and Digestibility of Improved Selections of Tall Fescue and Orchardgrass Hays

item Burns, Joseph
item Fisher, Dwight

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2009
Publication Date: 1/25/2010
Citation: Burns, J.C., Fisher, D.S. 2010. Intake and Digestibility of Improved Selections of Tall Fescue and Orchardgrass Hays. Crop Science. 50:419-426

Interpretive Summary: Tall fescue has been the major perennial cool-season grass grown across the north-south transition zone due to its long term persistence. Tall fescue has also been found to produce summer syndrome which is reflected in reduced animal daily performance and an unthrifty condition. Until recently this was attributed to the tall fescue plant giving it a negative connotation in nutritive value and quality. To that extent orchardgrass was considered a cool-season grass of superior quality but did not persist well in the upper south with stand losses evident by the 3rd or 4th year after establishment. Subsequently, an endophyte was found in tall fescue that provided increased tolerance to environmental stress but produced compounds that were toxic to the animal. This study evaluated two recently released tall fescue cultivars, MaxQ and Ark+ , that were inserted with a novel endophyte that improves plant survival but the endophyte does not produce compounds toxic to the animal. Also, a recently improved orchardgrass cultivar, Persist, was compared to the two improved tall fescue selections. The upshot is that the nutritive of the tall fescues and the orchardgrass were similar. Also, evaluation by goats and steers showed that one or the other improved tall fescue was similar in quality (intake and digestion) to orchardgrass. This provides the producer the choice of planting either tall fescue or orchardgrass, depending on the importance of persistence or other agronomic characteristics, without concern for forage quality.

Technical Abstract: Improved cool-season grass cultivars may add production potential to ruminant enterprises across the North-South transition zone. Quality among hays of ‘MaxQ’ (‘Jesup’ with novel endophyte), HM4 (‘HiMag’ with novel endophyte number 4) and ‘Cajun’ (without endophyte) tall fescues [Lolium arundinaceum (Schreb.) Darbysh.] and ‘Persist’ orchardgrass (Dactylis glomerata L.) was evaluated. Forage was harvested in the flag-leaf stage in 3 of 4 yr and a regrowth (late flag-leaf to heads emerging stage) in 1 yr. Goats (four trials) consumed MaxQ, HM4, and Persist similarly [P = 0.12; mean = 2.49 kg 100-1 kg body weight (BW)] and Cajun least (P <0.01; mean = 1.62 kg 100-1 kg BW). Apparent digestibility was similar among tall fescues (P = 0.07; mean = 609g kg-1) but MaxQ and Cajun were greater than Persist (P = 0.05; mean = 610 and 623 vs. 582 g kg-1). Digestible dry matter intake (DMI) was similar among MaxQ, HM4 and Persist (P = 0.09; mean 1.49 kg 100-1kg BW). Steers (3 trials and Cajun not evaluated), consumed more Persist than MaxQ (P = 0.01; 2.40 vs. 2.14 kg 100-1 BW) or HM4 (P = 0.01; 1.98 kg 100-1 BW). MaxQ had greater apparent digestibility than HM4 (P = 0.01) or Persist (P = 0.04; 626 vs. 585 vs. 597 g kg-1, respectively) but digestible DMI of MaxQ and Persist was similar (P = 0.12; mean = 1.39 kg 100-1 kg BW). Improved tall fescue cultivars with novel endophyte, offers the ruminant producer a cool-season forage of similar quality as orchardgrass for their enterprise.