2010 Annual Report
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.
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