Degree Type

Thesis

Date of Award

2017

Degree Name

Master of Science

Department

Animal Science

Major

Animal Science

First Advisor

Stephanie Hansen

Abstract

There are multiple programs producers can market cattle into including certified natural programs. These programs offer premiums for producers as an incentive to raise natural cattle that have slower growth rates because of the inability to utilize growth-promoting technologies. Because of tremendous improvements in genetics resulting in dramatic increases in growth rates of modern feedlot cattle, it is of value to investigate how to maximize the growth potential of these types of cattle. Trace minerals are essential for growth processes throughout the body. The supplementation of trace minerals has produced varying responses in regards to growth performance and carcass characteristics of cattle. However, there are several factors that can contribute to an animal’s trace mineral status and response to trace mineral supplementation including initial mineral status, environment, genetics, and stage of production. Thus, the objectives of this research were to: 1) evaluate the growth response and trace mineral status of certified natural Angus steers supplemented with dietary trace minerals and given an injectable trace mineral at different times in the feeding period and 2) evaluate the effect of supplementing dietary trace minerals at NRC recommendations or industry concentrations in non-implanted or implanted steers that receive high potency implant series. Within our first research objective, an injectable trace mineral had no effect on growth performance regardless of injection given at the start of the growing period, start of the finishing period, or at both time points, likely due to the steers having adequate trace mineral status throughout the feeding period. Injectable trace mineral did improve the trace mineral status of natural beef steers by increasing liver Cu, Zn, and Se concentrations during the growing period, as well as Cu and Se concentrations during the finishing period. After completion of our second research objective, we found there was a implant × trace mineral supplementation interaction during the first 56 days of the experiment on the first implant where growth rates were increased in implanted cattle that received supplemental trace minerals and subsequent body weights tended to follow a similar pattern. But there were no implant × trace mineral supplementation interactions for overall live or carcass adjusted animal performance. Hormone implants improved growth parameters and increased hot carcass weight. Trace mineral supplementation also improved dry matter intake and carcass adjusted final body weight, average daily gain, and improved feed efficiency regardless of implant status. Hormone implants decreased Cu and Mn concentrations 14 days after the implantation of a high dose potency implant. The varying concentrations of trace mineral supplementation increased liver Cu, Mn, Se, and Co concentrations 14 days post reimplantation and at harvest compared to steers receiving no trace mineral supplementation. The combination of utilizing hormone implants and supplementing steers at industry recommended concentrations of trace minerals produced the most favorable breakeven selling price of all costs. The findings of these experiments produced conflicting responses in regards to the effects of trace mineral supplementation on the growth rates of feedlot steers. These variable responses could be attributed to divergent mineral status, dietary concentrations of trace minerals, steer genetics, and growth rates. More research is warranted to better understand which mineral(s) may be responsible for producing a growth response in feedlot steers along with what concentrations are needed to optimize steer growth performance.

DOI

https://doi.org/10.31274/etd-180810-5014

Copyright Owner

Emma Kay Niedermayer

Language

en

File Format

application/pdf

File Size

151 pages

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