2011 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.
This is the final report of this research project. The single investigator on the project retired in 2011. Over this course of time, this project developed and transferred sustainable technologies, germplasm, management practices and integrative strategies to improve the conservation and use of pasture agro-ecosystems to support livestock production and other natural resource values.
Information is being obtained on the quality and utilization of four subtropical grasses and two cool-season grasses and the associated plant-animal factors that alter their conversion to value added animal products. Grazing Trials: One trial (3 years) compared the animal and pasture productivity of endophyte-free 'Au-Triumph' tall fescue when three management strategies were stocked to effect efficient herbage utilization relative to average daily gain and steer gain ha-1. The second trial (2 years) evaluated per animal and per ha productivity of flaccidgrass when stocked over a range of three forage mass (FM) levels to determine the influence of FM on digesta kinetics and dry matter intake (DMI) of steers (data in press). Findings: During spring (about 70% of seasonal production) endophyte-free tall fescue continuously stocked (CS) from April to July was compared with either a daily allowance (DA) or a lax (7 to 12d) rotation (LR). The FM was managed to average 2673 kg/ha for the CS and 3057 kg/ha at turn on and 2844 kg/ha residue for DA and 2851 kg/ha at turn on and 2559 kg/ha residue for LR. Steer daily gain, stocking rate gain and effective feed units/ha were not altered by management strategy averaging 0.95 kg/day, 6.7 steers/ha, 585 kg/ha, and effective feed units of 3111 kg/ha. Furthermore, canopies wer similar averaging 54.9% leaf, 32.6% dead, 11.9% stem and 0.5% hears. Tall fescue can be managed flexibly to enhance animal production systems. 'Carostan' flaccidgrass was continuously stocked during the summer at increasing FM ranging from 1245 to 3585 k/ha with neither mean retention time nor passage rates of either liquid or digesta phases altered by FM. Fecal output increased linearly (P=0.04) from short to tall (0.643 to 0.739 kg/100 kg BW) indicating possible variation in dry matter intake (DMI). However, DMI and disgestible DMIs were similar in in-vitro dry matter disappearance (mean=713 g/kg) and neutral detergent fiber (mean=468 g/kg) regardless of FM. 'Carostan' flaccidgrass canopies were flexible and no optimum height was detected to optimize diet composition. This species has potential as a pasture species when properly managed. Stall Trials: Several intake and digestion trials to compare Caucasian bluestem (CBS) with Coastal and Tifton bermudagrasses, switchgrass, and big bluestem were conducted and summarized and published during fiscal year 2011. Findings: CBS was evaluated in four experiments and was readily consumed by steers whether cut as initial or regrowth hays.
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 is also a possible candidate for cellulosic production for bio-fuel and is sufficiently pliable to be an integral part of ruminant production systems in the Mid–Atlantic Region. New forage management systems are now available to producers.
Burns, J.C. 2011. Maturity and Regrowth Influences on Quality of Caucasian Bluestem Hay. Crop Science. 51:1840-1849.
Burns, J.C., Fisher, D.S., Pond, K.R. 2011. Effects of Tall Fescue Forage Mass on Steer Ingestive Behavior and Performance. Crop Science. 51:1850-1864.
Chavez, S.J., Huntington, G.B., Burns, J.C. 2011. Use of Plant Hydrocarbons as External Markers to Measure Voluntary Intake and Digestibility in Beef Steers. Journal of Animal Science. 139:245-251.
Burns, J.C. 2011. Intake and Digestibility Among Caucasian Bluestem, Big Bluestem, and Switchgrass Compared with Bermudagrass. Crop Science. 51:2262-2275.