Degree Type

Dissertation

Date of Award

2014

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Peter M. Hoffman

Abstract

ABSTRACT

A four-year study was conducted using 1,987 yearling steers of predominantly mixed British breeds with an average starting weight of approximately 700 lb. The overall objectives of this study was to evaluate feedlot performance, carcass characteristics and expected economic projections for placing steers on feed quarterly per year for a period of 4 yr in different housing-diet systems. A pen with an average of 20 steers was the experimental unit, which was replicated once at the start of every trial period. Treatments were 2-levels of diet, 3-levels of housing, and season with 4-levels per year. The two diets were: 1) a mixture of processed high moisture corn grain (77% DM) providing 85% of the energy and whole plant corn silage, 2) a whole plant corn silage diet (35% DM). In addition, protein, vitamin and mineral supplement was provided to meet dietary requirements. Cattle were fed once per day in the morning. The housing treatments consisted of: 1) shelter; open lot with access to overhead shelter, 2) no shelter; open lot without access to an overhead shelter, but provided with a windbreak, 3) confinement; open front-side confinement barn. The four seasons involved were when steers were placed into the feedlot and fed through to market weight as follows: 1) December; winter, 2) March; spring, 3) June; summer and 4) September; fall. The effects of diet, housing, season, and cycle influenced ADG and final weight (P < 0.001), as well as the interaction of diet Ã? season (P < 0.05), but did not affect ADMI (P > 0.05). The FE was affected significantly by diet (P < 0.001) as well as the year and interaction of diet Ã? season (P < 0.05). The effects of diet, housing, season and year affected HCW and DP (P < 0.001). In addition, BF, KPH, YG and QG were affected by dietary treatment (P < 0.001) and season (P < 0.05), but not by the effects of housing (P > 0.05). Within the economic analysis using the annual scenario, shelter corn (SC) steers had 3.2% higher income per head than those in shelter silage (SS) facilities. Moreover, steers in no shelter corn (NSC) groups had 3.9% better income per animal than cattle fed in no shelter silage (NSS). Besides, steers fed in confinement corn (CC) received 2.2% higher income per head compared to those fed in confinement silage (CS) system. Overall, SC steers had the highest income per head, with a 6% advantage over the CS group, which had the lowest income per head. Steers that were put into the feedlot during the months of December, March, June and September and fed a corn-based diet had better returns than those fed a corn silage-based diet. Winter steers in NSS had the lowest income, which represented 7.4% difference between the highest incomes attained by steers in SC system. During spring and summer, the SC system had the highest income per steer, followed by NSC and then the CC group.

DOI

https://doi.org/10.31274/etd-180810-1971

Copyright Owner

Josephat Gichobi Njoka

Language

en

File Format

application/pdf

File Size

108 pages

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