Title page for ETD etd-10102003-120025


Type of Document Master's Thesis
Author Barlow, Rebecca Louise
Author's Email Address bbarlow@vt.edu
URN etd-10102003-120025
Title Yield, Quality, and Botanical Composition of AUtumn-Accumulated Grass-Legume Mixtures and Digestibility of Ensiled Autumn-Accumulated Orchardgrass and Alfalfa
Degree Master of Science
Department Animal and Poultry Sciences
Advisory Committee
Advisor Name Title
Fontenot, Joseph P. Committee Co-Chair
Smith, S. Raymond Committee Co-Chair
Abaye, Azenegashe Ozzie Committee Member
Allen, Vivien G. Committee Member
Keywords
  • winter grazing
  • forage quality
  • grass silage
Date of Defense 2003-09-11
Availability unrestricted
Abstract
Beef cattle producers in the southeastern US often stockpile forage in late summer to extend the grazing season and reduce feeding costs. Three stockpiled grass-legume mixtures were evaluated for winter grazing. In addition, stockpiled forages were ensiled and evaluated as livestock feed. Four accumulation dates and seven harvest dates were randomized to small plots of tall fescue (Festuca arundinacea Schreb.) -red clover (Trifolium pratense L.), orchardgrass (Dactylis glomerata L.) -red clover, and orchardgrass-alfalfa (Medicago sativa L.). The amount of grass and legume in the fescue-red clover mixture shifted from less than 30% grass and more than 60% legume in October to over 60% grass and less than 10% legume in April. All forage mixtures contained at least 15% CP from November to March. Fescue-red clover was higher in TNC and lower in NDF, ADF and cellulose in January and March than the orchardgrass-legume mixtures. Fescue-red clover was higher in yield than the orchardgrass-legume mixtures from November to February. Delaying stockpiling until September 1 or 15 increased (P <.05) legume content and decreased dead grass content in orchardgrass-clover and orchardgrass-alfalfa. Accumulating growth from September 15 increased percent CP in fescue-red

clover and orchardgrass-clover, compared to August 15, and decreased percent NDF in all forage mixtures. Percent IVDMD increased in orchardgrass-clover when stockpiling was delayed until September 15. May yields decreased only in orchardgrass-alfalfa when stockpiling was delayed until September. Orchardgrass stockpiled on August 3 and September 3, and alfalfa stockpiled on September 3 were ensiled alone. Chemical composition of silages was determined after 90 d of fermentation. Silages averaged 16.0% CP and 44.7% NDF. Digestibility of the ensiled stockpiled forages was estimated using acid insoluble ash as a marker with 18 wether lambs. No differences were observed in DM or CP digestibility, but NDF digestibility was lower for alfalfa silage than for orchardgrass silages. All stockpiled grass-legume mixtures provided high quality winter grazing, and all silages were of good quality and digestibility. Fescue-red clover maintained both good quality and higher yield than the other mixtures. Ensiling stockpiled alfalfa and orchard grass provided a method of maintaining CP and digestibility for subsequent feeding.

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