University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Theses and Dissertations in Animal Science Animal Science Department 8-2014 Effects of sorting prior to feeding Zilpaterol hydrochloride and effects of different implant strategies on feedlot performance and carcass characteristics of steers and heifers Fred H. Hilscher Jr University of Nebraska-Lincoln, [email protected] Follow this and additional works at: http://digitalcommons.unl.edu/animalscidiss Part of the Other Animal Sciences Commons Hilscher, Fred H. Jr, "Effects of sorting prior to feeding Zilpaterol hydrochloride and effects of different implant strategies on feedlot performance and carcass characteristics of steers and heifers" (2014). Theses and Dissertations in Animal Science. 90. http://digitalcommons.unl.edu/animalscidiss/90 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Theses and Dissertations in Animal Science by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. EFFECTS OF SORTING PRIOR TO FEEDING ZILPATEROL HYDROCHLORIDE AND EFFECTS OF DIFFERENT IMPLANT STRATEGIES ON FEEDLOT PERFORMANCE AND CARCASS CHARACTERISTICS OF STEERS AND HEIFERS BY Fred Henry Hilscher Jr. A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science Major: Animal Science Specialization: Ruminant Nutrition Under the Supervision of Professor Galen E. Erickson Lincoln, Nebraska August 2014 EFFECTS OF SORTING PRIOR TO FEEDING ZILPATEROL HYDROCHLORIDE AND EFFECTS OF DIFFERENT IMPLANT STRATEGIES ON FEEDLOT PERFORMANCE AND CARCASS CHARACTERISTICS OF STEERS AND HEIFERS Fred Henry Hilscher Jr., M.S. University of Nebraska, 2014 Advisor: Galen E. Erickson Two experiments evaluated the effects of sorting and feeding Zilpaterol hydrochloride (ZH) to steers on feedlot performance and carcass characteristics. In Exp. 1, treatments compared unsorted cattle either fed ZH or not, and three treatments utilizing 1 sort at the beginning, middle or end of the finishing period. In Exp. 2, treatments compared unsorted cattle fed ZH, and two treatments that utilized 1 sort based on initial BW or 4 sorts at the end of the finishing period. Feeding ZH increased BW, HCW and percentage of overweight carcasses; however, sorting decreased carcass weight standard deviations, and percent overweight carcasses. Feeding ZH increased carcass weight, but sorting reduced variation allowing increased carcass weight while minimizing overweight carcasses. Three experiments evaluated the effect of different aggressive implant strategies on feedlot performance and carcass traits of crossbred heifers and steers. In Exp. 3, heifers were implanted with Revalor-IH, Revalor-H, or Revalor-200 and all reimplanted with Revalor-200. In Exp. 4, steer treatments were Revalor-IS reimplanted with Revalor- 200 and Revalor-XS initially and reimplanted with either Revalor-IS, Revalor-S, or Revalor-200. In Exp. 5, steers were implanted with either Revalor-IS, Revalor-200, or Revalor-XS and reimplanted with Revalor 200. Final BW, ADG, and G:F were not different between implant strategies in Exp. 3, 4, & 5. Dressing percent, HCW, 12th rib fat, and yield grade did not differ between strategies in Exp. 3 & 4. Revalor-XS had greater LM area, decreased 12th rib fat, and yield grade compared to other implants in Exp. 5. Percent Choice was decreased and percent Select was increased with increased implant dosage in Exp. 3 & 5, with no differences in quality in Exp. 4. Aggressive implant strategies may not be beneficial during the feeding phase in steers and heifers. These aggressive implant strategies could negatively impact carcass quality in heifer and steer calves compared to utilizing a traditional low dose implant followed by a high dose terminal implant. iv Acknowledgements I would like to thank Galen Erickson for the opportunity to come to Nebraska and the doors that he has opened for me. I would also like to express my gratitude to Terry Klopfenstein, Matt Luebbe, and Kyle Vander Pol for serving on my committee and for all the comments, advice, and discussion. Thank you to all the graduate students that helped on these projects and also for all the round table discussions after work. I have made lifelong friends here and memories I will never forget. Thank you to the coordinators who answered questions and helped me when I needed it. I especially want thank Claire for standing by me and supporting me. I would lastly like to thank my mother and father for the continued love and support I have received all my life. My mother scarified her time continually to make sure I had every possible opportunity to succeed. My father inspired me to pursue animal agriculture and without him I would not be here today. Thank you all. v Table of Contents Introduction ........................................................................................................................7 CHAPTER I. Review of the Literature............................................................................9 Predicting Carcass Composition .....................................................................................9 Serial Harvest ..........................................................................................................10 Value of Additional Days on Feed ...........................................................................12 Visual Appraisal.......................................................................................................13 Body Measurements .................................................................................................15 Importance of Weight ...............................................................................................17 Sorting Feedlot Steers ...................................................................................................19 Sorting Strategies .....................................................................................................20 Beta-Adrenergic Agonists .............................................................................................24 Mode of Action of Beta-Adrenergic Agonists ..........................................................25 Live animal performance .........................................................................................29 Carcass characteristics ............................................................................................31 Growth Promoting Anabolic Steroids ...........................................................................32 Mode of Action of TBA & Estradiol Implants ..........................................................33 Live animal performance .........................................................................................35 Carcass characteristics ............................................................................................37 Implanting Strategies ...............................................................................................40 Use of Implants and Zilpaterol hydrochloride ..............................................................42 Conclusions ...................................................................................................................43 Literature Cited ..............................................................................................................45 CHAPTER II. Impact of sorting prior to feeding Zilpaterol hydrochloride on feedlot performance and carcass characteristics of yearling steers, .................54 Abstract .........................................................................................................................55 Introduction ...................................................................................................................56 Materials and Methods ..................................................................................................57 Results and Discussion ..................................................................................................65 Implications ...................................................................................................................71 Literature Cited ..............................................................................................................72 CHAPTER III. Impact of increasing initial implant dosage on feedlot performance and carcass characteristics of steer and heifer calves, ......................87 Abstract .........................................................................................................................88 Introduction ...................................................................................................................89 Material and Methods ....................................................................................................90 Results and Discussion ..................................................................................................98 Literature Cited ............................................................................................................105 vi LIST OF TABLES Chapter II. TABLE 1. COMPOSITION AND ANALYZED NUTRIENT CONTENT (DM BASIS) OF DIETS FED IN EXP. 1 AND EXP. 2 ......................................................................................................... 75 TABLE 2. ZILMAX