Degree Type

Dissertation

Date of Award

2003

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Jack C. M. Dekkers

Abstract

Electronic swine feeders are used to automatically measure individual feed intake on group-housed pigs and are often used in breeding herds. Data from these feeders contain errors. In addition, electronic feeders could affect performance of growing pigs and are expensive. To address these concerns, the objectives of this research were to develop and evaluate editing methods, to measure the effect of electronic feeders on performance, and to develop and evaluate strategies that maximize the number of pigs measured per feeder. The percentage of visits that contained errors, based on 16 criteria, ranged from 4.3 to 18.7% in three data sets and seemed to be largely affected by management of the feeder. A model was developed to adjust daily feed intake from error-free visits for the combined effect of errors. This and five other editing methods were then used to edit data from 124 pigs with simulated errors. The correlation of edited with true observations ranged from 0.82 to 0.96 for feed intake on a given day and from 0.93 to 0.99 for average daily feed intake. To evaluate the effect of electronic feeders on performance, 475 boars and gilts were fed using an electronic feeder or a conventional feeder. Body weight, backfat thickness, loin muscle area, and pen daily feed intake per pig were measured serially. Gilts on electronic feeders ate less, grew slower, and deposited less backfat and loin muscle area throughout the test period. There were no differences for boars. To maximize the number of pigs that are tested per electronic feeder, strategies of alternating the use of a feeder between pens of pigs were simulated in a complete data set that contained 12 weeks of feed intake data. When two pens were tested per feeder, the correlation between estimated and true average daily feed intake was 0.98 and 0.94 in ideal and poor data conditions, respectively. These results indicate that testing twice as many boars and using the appropriate editing method will increase the number of pigs tested and improve the accuracy of feed intake, which will in turn increase the rate of genetic progress in swine improvement programs.

DOI

https://doi.org/10.31274/rtd-180813-8788

Publisher

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

Copyright Owner

David Scott Casey

Language

en

Proquest ID

AAI3085892

File Format

application/pdf

File Size

175 pages

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