Author
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BURNS, JOSEPH - Retired ARS Employee |
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Fisher, Dwight |
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Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/20/2011 Publication Date: 8/19/2011 Citation: Burns, J.C., Fisher, D.S. 2011. Stocking strategies as related to animal and pasture productivity of endophyte-free tall fescue. Crop Science. 51:2868-2877. Interpretive Summary: Tall Fescue is the major cool-season perennial forage grown across the upper southern USA. In this humid transition zone tall fescue provides forage as both pasture and hay in ruminant production systems. Much of the past research has focused on fungal endophyte issues, N fertilizations, cutting or defoliation frequencies, time of defoliation, and height of defoliation whether grazed or stockpiled, or harvested as hay. Little attention, however, has been directed to the utilization of tall fescue from different defoliation regimes relative to a comparison of animal daily responses and pasture productivity at similar forage mass (FM). It is well established that throughout the transition zone supplemental N is a key to maintaining productive stands of pure tall fescue for pasture or generating an acceptable stockpile. Recommended annual applications of N, depending on stand use, can be upwards of 224 kg ha-1. This expensive input, coupled with the removal of the toxic endophyte (seeding cultivars that are either endophyte free or carrying a novel endophyte), warrants forage management strategies that assure efficient utilization that favors stand longevity. An experiment was conduct to determine the impact of using different stocking densities at about the same level of FM. Whether steers were continuously stocked, rotated daily, or every 7-12 d, steer daily gain and pasture productivity, as well as grazing behavior, was similar. In general, tall fescue provided a leafy canopy structure that permits some selective grazing regardless of management strategy and provides a diet of desirable nutritive value. Tall fescue that is free of endophyte, or contains a nontoxic endophyte, provides a high degree of management flexibility and is an excellent forage to serve as a component of animal production systems across the north-south transition zone. Technical Abstract: Tall fescue [Festuca arundinacea Schreb.) is a well adapted perennial grass used for pasture across the north-south transition zone in the USA. This 3-yr trial evaluated three stocking strategies to utilize well-fertilized spring (April to July) growth of endophyte-free tall fescue for steer and pasture production. Continuous stocked (CS) was compared with a daily allowance (DA) or lax (7 to 12 day) rotation (LR). Forage mass (kg ha-1) averaged 2673 for CS, and 3057 at turn on and 2844 residual for DA, and 2851 at turn on and 2559 residual for the LR. Canopies were similar being mainly leaf (54.9 %), followed by dead (32.6 %), stem (11.9 %) and head (0.5 %) fractions. Steer daily gains (0.95 kg), stocking rate (6.7 steers ha-1), gain ha-1 (585 kg), and Effective Feed Units (3111 kg ha-1) were similar among stocking strategies. Canopy in vitro true organic matter disappearance (IVTOD) was similar (747 g kg-1) among treatments but differed in CP averaging 186 g kg-1 for CS vs. 198 g kg-1 for rotations. Further, DA was less in CP than LR (189 vs. 207 g kg-1) but greater in NDF (623 vs. 594 g kg-1). Diet selected was similar among treatments in IVTOD (885 g kg-1), CP (245 g kg-1), and NDF (457 g kg-1) as was daily grazing time of 11.5 h when monitored by Vibracorder or 12.3 h when monitored by computer. Well fertilized tall fescue pastures free of toxic endophyte can accommodate a range of stocking strategies when efficiently utilized in animal production systems. |
