"December 2013.""A Thesis presented to the Faculty of the Graduate School University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science."Thesis advisors: Dr. Monty S. Kerley and Dr. Bryon Wiegand.Efficiency in ruminants has historically been improved by using antibiotics and ionophores to alter rumen fermentation. Nutritionists, however, have begun searching for alternative rumen modifiers due to the negative attention received by non-therapeutic antibiotic use. Plant extracts, like essential oils, are being explored as a potential alternative to alter fermentation and improve growth and efficiency in ruminants. Essential oils are naturally occurring, secondary metabolites that can be distilled or extracted from most plants and possess antimicrobial properties. Next Enhance® (NE, Novus International Inc.) is comprised of garlic (diallyl disulfide) and cinnamon (cinnamaldehyde) extracts; both have demonstrated the ability to modify fermentation. A series of experiments was conducted to determine how feeding NE affects in vitro fermentation, site and extent of nutrient digestion, feedlot performance, carcass traits, meat quality, and consumer sensory characteristics of LM steaks from beef steers. The first experiment in this thesis examined how feedlot steer performance and carcass traits were affected by NE feeding. ADG and G:F were improved early in the feeding period by 150 mg·hd-1 ·d-1 targeted NE inclusion. DMI, overall ADG, and overall G:F were not affected by NE inclusion. All NE levels improved dressing percent, 12th rib backfat, LM area, and calculated USDA yield grade. Steers fed 150 mg·hd-1 ·d-1 NE yielded carcasses worth nearly $30 more than control steers. LM steaks were obtained from five head/treatment and used to evaluate meat quality and consumer sensory characteristics. L*, a*, and b* color values were not affected by TRT on d 0 or 14. Cook loss percent was increased when low NE levels were fed but decreased by high NE doses. Warner-Bratzler shear force, and percent drip loss, moisture, and fat were not affected by NE inclusion. A consumer sensory panel reported no difference in beef steer LM steak organoleptic properties due to NE. NE inclusion at 150-300 mgIncludes bibliographical references (pages 73-80)
