Animal Science Department

 

Date of this Version

8-2014

Citation

Hilscher Jr., F. H. 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. MS Thesis, Univ. of Nebraska, Lincoln

Comments

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

Copyright (c) 2014 Fred Henry Hilscher Jr.

Abstract

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.

Advisor: Galen E. Erickson

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