Graduate Studies
First Advisor
James C MacDonald
Date of this Version
8-2023
Abstract
A backgrounding experiment (Exp 1) was conducted over two years to determine the interactions of winter rate of gain at a high gain (HIGH) of 0.91 kg and low gain (LOW) 0.45 kg, and implant strategy in the winter and summer phases and subsequent effects in the finishing phases. The first factorial was a 2C2C2 with factor one being high or low gain during the winter period, factor two implant or no implant during the winter, and factor three implant or no implant during the summer phase. The second factorial was also a 2C2C2 utilizing pen-fed steers to achieve similar ADG as the HIGH and LOW steers grazing corn residue. The first factor is a rate of gain at either HIGH or LOW. The second factor was implant strategy in the summer phase receiving an implant or no implant. Steers were penned in experimental units during the summer phase and fed a forage-based diet. In the finishing phase, all steers were placed on a common finishing program. In the winter phase, HIGH and LOW steers gained 0.95 and 0.53 kg/d (P < 0.01). Steers on the HIGH treatment housed on corn residue had greater ADG than those housed in pens, 0.95 and 0.88 kg/d respectively. In the summer, LOW steers gained 0.95 kg/d vs. 0.84 kg/d for HIGH steers (P < 0.01). At the conclusion of finishing, HIGH resulted in 45 kg more final BW than LOW steers (P < 0.01) while the Rev-IS implant during the summer phase resulted in 38 kg of additional final BW over non-implanted steers (P < 0.01). Supplementing at a high rate of gain during the winter backgrounding phase and implanting in the winter and summer results in the greatest total system gain and HCW. A grazing experiment (Exp 2) was conducted to evaluate the performance of steers grazing smooth bromegrass pastures supplemented dried distillers grains plus solubles (DDGS) either daily or three times per week. Treatments consisted of 1) steers supplemented DDGS daily 2) steers supplemented DDGS three times a week and 3) steers that received no supplementation (control). The control calves gained 0.85 kg/d. The supplemented treatments significantly increased (P < 0.01) ADG compared to the control, with daily supplementation gaining 1.25 kg/d and 3x gaining 1.11 kg/d. Ending BW and ADG was decreased (P < 0.01) with 3x a week compared to daily supplementation. For steers grazing smooth bromegrass pastures, daily supplementation of DDGS resulted in greater gains and ending BW when compared to three times a week supplementation, which were both greater than not supplementing.
Advisor: James MacDonald
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, Under the Supervision of Professor James C. MacDonald. Lincoln, Nebraska: August 2023
Copyright © 2023 Sydney T. Vanderhoff