Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Animal Science

First Advisor

Amanda D. Blair


The overall objective of this study was to determine if the level of growth promotant technology used among production systems influence animal and carcass performance, meat quality, production economics, the environmental impact, and determine consumer preferences and perception. Angus � Simmental steer calves (n =120) were stratified by birth date, birth weight, and dam age in a completely randomized design and assigned to one of four treatments: 1) no antibiotics (NA, receiving no technology); 2) non-hormone treated (NHTC, fed monensin and tylosin); 3) implant (IMPL, administered a series of three implants), and 4) implant plus fed a beta-agonist (IMBA, administered the same implant strategy as IMPL plus, fed ractopamine-HCI for the last 30 d prior to harvest). Animal weight, production expenses, and environmental factor data were collected from the production segments including: cow-calf, backgrounding, and finishing. During the finishing segment, animal feed intake, average daily gain (ADG), and efficiency was obtained. Carcass meat quality and yield performace was assessed. Striploins were collected for analyses post fabrication. Steaks were designated to specific postmortem aging periods, utilized for Warner-Bratzler shear force (WBSF), crude fat, and consumer sensory analyses. The consumer analyses evaluated beef production system information undisclosed and disclosed or simiply, without and later with information to assess palatability only, perception only, and perception plus palatability among untrained consumer panelists. IMPL had the greatest (P < 0.01) ADG and gain to feed (G:F). The final calculated body weight and hot carcass weight was similar (P > 0.05) and heavier (P < 0.01) for IMPL and IMBA in comparison to NA and NHTC, which were similar (P > 0.05). The actual branded carcass value was similar (P > 0.01) for NA and IMPL and greater (P < 0.05) than NHTC and IMBA, which was similar (P > 0.05). Excluding the cost of the calf, production costs were similar (P > 0.05) and lowest (P < 0.05) for NA and IMPL, NHTC was intermediate (P < 0.05), and IMBA had the greatest (P < 0.05) production cost. Net return was similar (P > 0. 01) between NA and IMPL, which was greater (P < 0.01) than NHTC and IMBA, which were similar (P > 0.01). In the environmental analysis, IMPL reduced GHG (CO2e/kg HCW) emissions by 8%, energy use (MJ/kg HCW) by 6%, water use (kg H2O/kg HCW) by 6%, and reactive N loss (g N/kg HCW) by 6%. The IMBA reduced GHG emissions by 7%, energy use by 3%, and reactive N loss by 1%. Meat quality analyses for marbling score and crude fat among NA and NHTC did not differ (P > 0.05) but were greater (P < 0.05) than IMPL and IMBA, which were similar (P > 0.05) and lower in crude fat. Steaks from NA and NHTC did not differ (P > 0.05) for WBSF though were more tender (P ≤ 0.05) than IMPL and IMBA, which were similar (P > 0.05) and tougher (P ≤ 0.05). During the Undisclosed without Meat panel, NA was most preferred (P ≤ 0.05) and IMBA was least preferred (P ≤ 0.05) while NHTC and IMPL were intermediate and similar (P > 0.05). All samples differed (P ≤ 0.05) during the Disclosed with Meat panel where, NHTC was most preferred followed by NA, IMPL, and IMBA. Despite improvements from use of monensin, tylosin, growth promoting implants with and without ractopamine HCl, cattle within IMPL and IMBA resulted in greater animal and carcass weights, were most effective at minimizing the environmental impact, and improved producer net return (IMPL only). However, consumers may have detected reductions in tenderness and palatability as IMPL and IMBA were least preferred. Consumers preferred the palatability of meat raised with judicious use of antimicrobials and antibiotics to ensure animal health when production information was disclosed (NHTC).

Library of Congress Subject Headings

Beef cattle -- Growth.
Beef cattle -- Feeding and feeds.
Beef -- Quality.
Meat -- Quality.
Beef cattle -- Carcasses.
Beef cattle -- Composition.
Beef industry.


Includes bibliographical references



Number of Pages



South Dakota State University

Webb-Megan-2018-PACLA.pdf (184 kB)
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