Genetic Aspects of Feet and Legs Soundness in Swine1

Records of 278 Duroc and 276 Yorkshire gilts confined to pens with concrete floors and fed a 16% protein diet ad libitum from 8 weeks of age until taken off test at 91 kg were analyzed for feet and legs (F-L) soundness as visually appraised. Front and rear F-L were scored separately from zero to 10 (best). Other traits were weight per day of age at start of test (W/A), average daily gain (ADG) on test, back-fat (BF) and loin eye area (LEA), the last two measured ultrasonically at 91 kilograms. Front and rear F-L scores (00B1; standard deviations) averaged 7.99 ± 1.32 and 7.88 ± 1.09, respectively. Components of variance and covariance were computed for sires within breed and year-season (104 df), dams within sires (89 df) and progeny within dams (353 df). Heritability estimates for front and rear F-L scores (00B1; standard errors) were 26.9 ± 20.5% and 15.2 ± 24.1%, respectively, with sire components and 27.9 ± 10.8% and 38.9 ± 11.2%, respectively, with sire + dam components. Genetic correlations between W/A, ADG, BF and LEA with front F-L scores were .035 ± .159, .334 ± .171, .350 ± .178 and −.327 ± .210, respectively; with rear F-L scores, they were .087 ± .139, .093 ± .158, .052 ± .166 and −1.86 ± .191, respectively. Results indicate slow to moderate rates of progress in F-L soundness by direct selection and no conflict with ADG but problems with BF and LEA.