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Changes in the physiology and feed quality of prairie grass during regrowth


Turner, LR and Donaghy, DJ and Lane, PA and Rawnsley, RP, Changes in the physiology and feed quality of prairie grass during regrowth, Agronomy Journal, 98, (5) pp. 1326-1332. ISSN 0002-1962 (2006) [Refereed Article]

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Copyright Statement

Copyright 2006 American Society of Agronomy

DOI: doi:10.2134/agronj2005.0309


Species-specific grazing management is required to maximize the potential of perennial grass species, and it follows that the optimal performance of prairie gross (Bromus willdenowii Kunth.) as a dairy pasture species is reliant on a customized optimal grazing interval. The aim of the present study was to investigate morphological and physiological changes in prairie grass during regrowth to establish a basis for optimum defoliation management of prairie grass pastures. Greenhouse treatments consisted of one preliminary harvest followed by six sequential harvests at each leaf regrowth stage front one to six fully expanded leaves per tiller. Leaf tissue, stubble tissue below 50 mm and roots were collected at each harvest event. Root and stubble samples were analyzed for water-soluble carbohydrates (WSC). Leaf samples were analyzed for P, K, Na, Mg, Ca, and N concentrations and metabolizable energy (ME) was predicted by near-infrared spectrometry (NIRS). This study confirmed that the tiller base in prairie grass is the primary storage organ for WSC and that leaf growth has the highest priority for available energy following defoliation, followed by root growth and tiller initiation. A defoliation interval based on the 4-leaf stage of regrowth enabled adequate time for prairie grass to replenish WSC reserves, resume root growth and initiate new tillers, before the onset of significant leaf senescence and consequent reduction in feed quality. At the 4-leaf stage, feed quality was relatively high (ME > 11.80 MJ kg -1 DM), with concentrations of P, K and Na adequate to meet the needs of a high-producing dairy cow. Concentrations of Ca and Mg were insufficient to meet these requirements throughout the regrowth cycle. © American Society of Agronomy.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Agronomy
Objective Division:Animal Production and Animal Primary Products
Objective Group:Pasture, browse and fodder crops
Objective Field:Sown pastures (excl. lucerne)
UTAS Author:Turner, LR (Dr Lydia Turner)
UTAS Author:Donaghy, DJ (Associate Professor Danny Donaghy)
UTAS Author:Lane, PA (Associate Professor Peter Lane)
UTAS Author:Rawnsley, RP (Dr Richard Rawnsley)
ID Code:35982
Year Published:2006
Web of Science® Times Cited:16
Deposited By:Agricultural Science
Deposited On:2006-08-01
Last Modified:2013-12-16

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