The Relation of External Body Characters to Annual Production in Barred Plymouth Rocks

Interrelationship of Body Weight, Production, and Egg Weight

“…There is some difference of opinion in regard to the relationship of these factors. Robertson (1931) reported extensive data indicating that the average body weight of pullets is correlated with their annual egg record, while Jull (1924), Piatt (1926), Sherwood (1922), and Hervey and Lewis (1924) reported work that showed that little or no correlation existed between body weight and annual egg production. Piatt (1926), Marble (1930), and Upp and Thompson (1927) [227]…”

Heritability Estimates and Genetic Correlations Among Several Traits in a Meat-Type Poultry Population ,

“…In addition, most workers have not indicated the variance of their estimates, thus making it difficult to determine whether two or more estimates, although numerically different, are in fact significantly different from each other. Hervey and Lewis (1923), Jull (1924), and Knox (1934) obtained estimates of correlations between several economic traits in laying birds. These were phenotypic correlations however and, thus, unreliable as estimates of the degree to which traits are genetically related.…”