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United States Department of Agriculture

Agricultural Research Service


Location: Plant Science Research

2010 Annual Report

1a.Objectives (from AD-416)
Identify and characterize alternative management strategies in the humid Southeast for integrating gamagrass and switchgrass into traditional pasture and livestock production systems by evaluating interactions between forage management options, plant performance and animal performance, and increased agronomic knowledge for producing biomass crops.

1b.Approach (from AD-416)
This project will be conducted jointly between USDA-ARS and the North Carolina Agricultural Research Service representing a true cooperative program (Burns, 2006). In this program the state of North Carolina contributes experimental animals and major field, animal, and laboratory facilities and technical assistance as well as routine maintenance needs for all facilities to meet the objectives of the research and the contributions from both will be detailed below.

3.Progress Report
Information is being obtained on the quality & utilization of four subtropical grasses & two cool-season grass & the associated plant-animal factors that alter their conversion to value added animal products.

Grazing Trials: Process – Two grazing trials were summarized for publication during FY 2010: One trial (3 years) compared the animal & pasture productivity of endophyte-free ‘Forager’ tall fescue when stocked over a range of herbage mass levels (3) to determine the optimum herbage mass for average daily gain & steer gain ha-1. The second trial (3 years) evaluated per animal & per ha productivity of switchgrass when stocked over a range of three herbage mass levels to determine the optimum herbage mass for steer average daily gain & steer gain ha-1. Responses are being merged with years 1&2.

Findings: During spring (about 70% of seasonal production) endophyte-free tall fescue continuously stocked at increasing stocking (from 6.1 to 8.2 steers ha-1 ) & decreasing forage mass(FM) (from 3812 to 1450 kg ha-1) gave similar steer daily gains (0.88 kg), but animal days ha-1 increased linearly from 413 to 543. Steer gain ha-1 was similar (mean = 392 kg) & effective feed units increased linearly (from 1712 to 2256 kg ha-1). Increased stocking gave a linear increase in canopy digestibility & decrease in neutral detergent fiber (NDF). Fall canopies with FM decreasing from 3494 to 1556 kg ha-1 were similar in digestibility (774 g kg-1) & NDF (550 g kg-1). Tall fescue can be managed flexibly to enhance animal production systems.

‘Kanlow’ switchgrass was continuously stocked during spring at increasing forage mass (FM) ranging from 818 to 3228 kg ha-1 with associated stocking of 5.8 to 8.2 steers ha-1. Steer average daily gain was not altered (mean = 1.11 kg) by changes in FM nor was animal days ha-1, weight gain ha-1, or effective feed units ha-1. During the summer, when FM increased from 465 to 2388 kg ha-1, steer daily gain was not altered (mean = 0.33 kg ) but steers selected a diet that was similar in digestibility (mean = 626 g kg-1) but decreased linearly from tall to short in NDF (665 vs. 645 g kg-1). Continuous stocking of switchgrass is feasible during spring, but rotational stocking maybe needed in summer to maintain adequate canopy-leaf mass.

Stall Trials: Process - Several intake & digestion trials to determine the potential of Caucasian bluestem at different maturities & initial vs. regrowth were summarized for publication during FY 2010.

Findings: Caucasian bluestem (CBS) was readily consumed by mature wether lambs when cut in the early-boot stage. Lambs consumed 1.88% of body weight with a digestibility of 64.7%. Increasing maturity to post anthesis reduced intake linearly to 1.45% of body weight as well as digestibility to 54.8%. Regrowth forage cut in early-boot stage was consumed at 2.03% of body weight & had a digestibility of 62.0%. Steers consumed regrowth CBS well with an intake of early-boot hay of 2.73% of body weight with digestibility of 67.0%. Intake & digestibility decreased linearly from early boot to post anthesis (cut 10 Sept.) avg 1.75% of body weight with digestibility declining to 51.7% by the Sept. cut.

1. Caucasian bluestem: It’s potential in production systems for the humid Southeast. Experiments were conducted by ARS Researchers at Raleigh, NC to determine if Caucasian bluestem was sufficiently pliable to be used as a pasture and hay source, in the Mid-Atlantic Region. Caucasian bluestem was grazed to obtain an estimate of steer daily performance and potential pasture production and cut and preserved as hay to determine its nutritive value and quality. Caucasian bluestem, also a possible candidate for cellulosic production for bio-fuel, is sufficiently pliable to be an integral part of ruminant production systems in the Mid–Atlantic Region.

Review Publications
Sauve, A.K., Hunington, G.G., Whisnant, C.S., Burns, J.C. 2010. Intake, Digestibility and N Balance of Steers Fed Gamagrass Baleage Topdressed at Two Rates of N and Harvested at Sunset and Sunrise. Crop Science. 50:427-437

Burns, J.C., Fisher, D.S. 2010. Intake and Digestibility of Improved Selections of Tall Fescue and Orchardgrass Hays. Crop Science. 50:419-426

Burns, J.C., Fisher, D.S. 2010. Eastern Gamagrass Management for Pastures in the Mid-Atlantic Region: I. Animal Performance and Pasture Productivity. Agronomy Journal. 102:171-178

Burns, J.C., Fisher, D.S. 2010. Eastern Gamagrass Management for Pastures in the Mid-Atlantic Region: II. Diet and Canopy Characteristics and Stand Persistence. Agronomy Journal. 102:179-186

Xu, J., Cheng, J.J., Sharma-Shivappa, R.R., Burns, J.C. 2010. Lime Pretreatment of Switchgrass at Mild Temperatures for Ethanol Production. Bioresource Technology. 101:2900-2903

Yang, Y., Sharma-Shivappa, R., Burns, J.C., Cheng, J.J. 2010. Saccharification and Fermentation of Dilute-Acid-Pretreated Freeze-Dried Switchgrass. Energy and Fuels. 23:5626-5635

Vibart, R.E., Burns, J.C., Fellner, V. 2010. Effect of Replacing Total Mixed Ration with Pasture on Ruminal Fermentation. Professional Animal Scientist. 26:435-442

Last Modified: 7/10/2014
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