Degree Type

Dissertation

Date of Award

2004

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Marjorie A. Faust

Abstract

The objectives of this research were to: (1) express variation in DHIA herd performance measures by means of limited number of factors, (2) determine the relationship of DHIA performance measures to profit score and their sensitivity to market price changes, (3) identify which herd performance measures changes were associated with profit score changes over five-year horizon.;For the variability in DHIA herd performance measures large variation among herds would indicate notable opportunity for changing management strategy. It was concluded that three independent factors offer the greatest opportunity for improvement within most production subsets. Notably, the reproductive measures of calving interval, days open, and percent cows bred >3 times accounted for a large portion of variability among herds. Also, considerable variation among herds for percent cows with SCS 4--5 and cows with SCS >5 suggests that management practices or their successful implementation at preventing mastitis differ greatly from farm to farm.;Simple regression was used for determining the relationship of DHIA performance measures to profit score and performance measures are sensitivity to market price changes. It was determined that (1) several measures were related to profit score by quadratic effects, (2) for measures with quadratic relationship to profit score, resulting changes in score for herds are dependent on the current herd performance for the respective measure, and (3) milk yield was not the only measure that significantly impacted profit score.;Sensitivity analysis indicated that several of the performance measures were sensitive to milk price changes. These price sensitivities suggest that producers need to consider economic conditions when assessing the importance of different management changes.;Lastly, herds which differed in realizing changes for profit score over a five-year horizon were identified, characterized for performance measures, and performance changes that were associated with profit score changes were determined. Changes in milk yield were not associated with changes in profit score for herds that either significantly or consistently increase profit over time. Rather, it was shown that average annual changes in reproductive measures had more important effect on changes in profit score for herds that were less profitable.

DOI

https://doi.org/10.31274/rtd-180813-185

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Michal Lunak

Language

en

Proquest ID

AAI3145668

File Format

application/pdf

File Size

128 pages

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