Degree Type

Dissertation

Date of Award

1981

Degree Name

Doctor of Philosophy

Department

Animal Science

Abstract

Individual records on feed consumption, body weight, and egg mass from 4909 pedigreed Single Comb White Leghorns from two populations, Q and R, were used to study the additional genetic gain in feed efficiency associated with individual feed consumption records. This was done by estimating the heritability of the residual component of feed consumption and by comparing selection indexes with and without records on individual feed consumption from all or a selected fraction of the individuals in a population;The residual component of feed consumption, defined as feed consumption statistically adjusted for body weight and egg mass, was moderately heritable in Q and R. Theoretically, the residual might be determined by genetic differences in digestive or metabolic efficiency or by behavioral traits i.e., feed wastage or physical activity;Inclusion of individual feed consumption information as a variable in a selection index is estimated to increase income over feed costs between 15 to 28 percent with truncation selection of the top 38 percent of the population. Using a selection index which includes body weight and egg mass at stage 1, followed by truncation selection of the top 16 percent of the remaining population using an index which includes body weight, egg mass, and feed consumption at stage 2 is estimated to increase income over feed costs by 7 to 20 percent;These findings imply that keeping individual feed consumption records on all or a selected fraction of the individuals in a population, will facilitate the genetic improvement of efficiency of feed utilization for egg production in layer-type chickens.

DOI

https://doi.org/10.31274/rtd-180813-4649

Publisher

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

Copyright Owner

Terry L. Wing

Language

en

Proquest ID

AAI8122576

File Format

application/pdf

File Size

120 pages

Included in

Genetics Commons

Share

COinS