Forage quality, animal performences, and carcass traits of steers finished on winter annual ryegrass (Lolium multiflorum Lam.) pasture with varying levels of corn supplementation
Type of DegreeThesis
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Crossbred steers (n=72) from E.V. Smith Beef Research Unit resident herd were selected to study forage based finishing systems using winter annual ryegrass (Lolium multiflorum Lam.) with varying levels of supplementation. In December 2003, cattle were allotted to one of six treatments with diets consisting of ryegrass pasture (1 ha) with whole shell corn supplemented at 0.0% (0.0), 0.5% (0.5), 1.0% (1.0), 1.5% (1.5), and 2.0% (2.0) of bodyweight, or ad-libitum mixed ration grain diet in drylot (GRAIN). Steers were randomly placed in pens of four with pen serving as the experimental unit. Cattle were harvested by pen when average pen backfat thickness reached approximately 6.35 mm. Forage samples and disk meter height were taken from ryegrass paddocks on a monthly basis to determine forage quality and mass. Following harvest of cattle, live animal performance, carcass traits, and proximate analysis, WBS, and sensory characteristics from the longissimus muscle (LM) of the rib section were analyzed. Finishing diet had no significant effect (P > 0.05) on animal performance as indicated by similar ADG and days on feed among diets. GRAIN and 2.0 treatments had a higher (P < 0.05) dressing percentage than 0.0 and 0.5 steers. Yield grade was lower (P < 0.05) for 0.0, 0.5 and 1.0 steers than those finished in the GRAIN group. Marbling scores and lean maturity were similar (P > 0.05) among treatments. WBS and sensory scores were unaffected (P > 0.05) by diet with the exception of lower (P < 0.05) sustained tenderness scores for 1.0 treatment. Forage quality was similar (P > 0.05) across pasture treatments for neutral detergent fiber, acid detergent fiber, and protein, while ash was higher (P < 0.05) in the 0.0 paddocks. In April, an incremental increase (P < 0.05) in dry matter mass (3312 kg ha-1 to 6973 kg ha-1) within paddocks was found with each increase in the amount of supplemental grain. Supplementation of finishing steers on annual ryegrass had little effect on animal performance, carcass traits, and palatability attributes. Forage mass was increased by adding supplemental corn to the diet.