Date of Award

8-2008

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

John C. Waller

Committee Members

Kelly R. Robbins, Gary E. Bates, James B. Neel

Abstract

A four year study (2004-2007) was conducted at Highland Rim Research and Education Center near Springfield, TN to compare tall fescue (Lolium arundinaceum Schreb.) forage systems in which rye (Secale cereale L.)/ryegrass (Lolium multiflorum Lam.) was used to supply additional high quality forage to stocker cattle. Twelve 1.2-ha pastures were assigned to two cool-season forages and two forage systems with three replicate pastures each. Cool-season forage treatments were: (1) endophyte-infected (Neotyphodium coenophialum) ‘Kentucky-31’ tall fescue and (2) ‘Jesup MaxQ’™ tall fescue. The two forage systems were: (1) stockpiled tall fescue, supplemental feed (a blend of byproduct feeds formulated to provide energy and protein equivalent to tall fescue hay) during winter, spring growth tall fescue and (2) stockpiled tall fescue, rye/ryegrass during winter when available, spring growth tall fescue and rye/ryegrass. Forage systems containing rye/ryegrass were established by drilling 38 kg of rye and 6.8 kg ryegrass in a prepared seedbed in 0.4 ha of the allotted 1.2 ha pasture area. All pastures were clipped in late spring to assure vegetative growth. In late-November, four weaned beef steers were randomly allotted to each pasture based on age, weight, and breed and remained on pastures until mid to late June. Steers grazed rye/ryegrass when it reached average height of 20 cm and were removed at an average height of 8 to 10 cm. Forage heights of rye/ryegrass before and after grazing and the number of days grazing was recorded. When forage was unavailable or insufficient, cattle were fed a byproduct-based supplement. Animal weights were collected on two consecutive days at the beginning and end of the trial. Data collected at 14-d intervals included: steer weight, forage availability by clipping strips (2 per 0.4-ha pasture), and blood serum for prolactin. Data were analyzed using the MIXED procedure of SAS and differences determined at P < 0.05. Steers grazing Jesup MaxQTMpastures gained more (P < 0.05) weight and had higher (P < 0.05) serum prolactin levels than those grazing KY-31 regardless of presence of rye/ryegrass.

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