Department of Animal Science
First Advisor
Galen E. Erickson
Date of this Version
4-2020
Citation
Schumacher, E. A., 2020. Evaluation of Protein Sources and Holstein Finishing Systems for Organic Beef Production and a Comparison of Single and Dual Implant Strategies in Finishing Heifers . University of Nebraska-Lincoln. A Thesis.
Abstract
Two in situ experiments were conducted to compare the rumen undegradable protein content (RUP) and RUP digestibility of conventional and organic field peas, fish meal, dehydrated alfalfa, and soybean meal. Significant differences were detected between feed samples in both studies for all variables measured. Variation existed between sample types but the data did not suggest that organic and conventional feeds are different when processed with the same methods. A performance experiment was conducted utilizing individually fed Holstein steers comparing the effect of RUP source in a simulated organic production system. Dietary treatments were: no supplemental protein (NONE), field peas (FP), field peas and fish meal (FPFM), soybean meal (SBM), or SoyPass (SP). Steers fed FPFM were more efficient than those fed NONE, with the other protein sources intermediate. These data indicated that conventional values of protein degradability may be used to formulate organic diets, and that similar performance can be achieved with a variety of different RUP sources. A commercial feedlot study compared two implant strategies on growth performance and carcass characteristics. Heifers were implanted with Synovex ONE Feedlot (day 0, ONE) or Synovex Choice (day 0) followed by Synovex Plus (day 93-95, CH/PLUS). Heifers implanted with CH/PLUS had lower marbling scores and calculated yield grade but greater DP and LM area compared to heifers implanted with ONE. No other differences were observed. These results indicated flexibility in implant strategy.The performance of Holstein bulls and steers was evaluated in a simulated organic production system harvested at 308, 343, 378, and 413 days on feed (DOF) was compared. Bulls had greater ADG, DMI, live BW, and HCW than steers, while steers had greater 12th-rib fat thickness. Steers showed greater linear increases in marbling scores than bulls as DOF increased. Live BW, DMI, and HCW responded linearly as DOF increased. These data suggest potential for improved animal performance feeding Holstein bulls in an organic system.
Advisor: Galen E. Erickson
Comments
A THESIS Presented to the Faculty of The Graduate College of the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under Supervision of Professor Galen E. Erickson. Lincoln, NE: May, 2020
Copyright 2020