Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science


An exploratory study of heritable differences in chemical components of chicken excreta is presented. Major emphasis was placed on the estimation of heritability and of phenotypic and genetic correlations for wet and dry feces production per day, for percentages of fecal protein, fecal metabolizable energy, and the ratio of phosphorus excreted to phosphorus intake. Traits measured on feces were considered as indicator traits for possible use in a selection program. In addition, estimations of population parameters for the economically important traits--feed consumption, body weight, age to sexual maturity, rate of egg production, and egg mass output--were obtained. The correlation between the indicator traits and the economic traits were then measured to determine the potential value of the former in predicting the genetic gain from selection for efficiency of egg production;The experimental population consisted of 741 pedigreed Single Comb White Leghorns representing four different lines in two experimental years;The results show evidence for the existence of heritable variance for the fecal traits. Also, evidence for the existence of a genetic residual component for dry feces was obtained. The inclusion of dry feces as an indicator trait into a selection index, that includes also body weight and egg mass, may be of practical use in a breeding program for the genetic improvement of feed efficiency for egg production.



Digital Repository @ Iowa State University,

Copyright Owner

Jose Espinoza-Velazquez



Proquest ID


File Format


File Size

95 pages