Genotypic and phenotypic parameters of spur incidence and length in White Leghorn hens

Spurs were measured on two groups of hens: at 532 days of age in six selected and three control strains (Expt. 1); and at 483 days of age in a full 3 X 3 diallel of three of the selected strains as well as two control strains and two commercial stocks (Expt. 2). There were no significant differences in length between spurs on right and left legs. Strain differences for spur incidence were large and significant, but those for length generally were not. Pooled strain estimates of heritability for spur incidence were .21 for both left and right spurs, and .40 (left) and .44 (right) for spur length (Expt. 1). General combining ability was large and highly significant for spur incidence only, and specific combining ability was not significant for either incidence or length of spurs (Expt. 2). Heterosis was not significant for spur incidence or length. Reciprocal differences were significant only for spur incidence of the crosses of strains 4 and 8. Spur length was negatively correlated phenotypically with egg production, egg weight, specific gravity, and Haugh units. Genotypically, spur length was positively correlated with part-record egg production to 273 days and negatively correlated with 450-day egg weight and specific gravity.