Genetic Parameters Estimates for Lean Growth Rate and Its Components in U. Determining Inbreeding Levels for the Navajo- Churro Sheep Breed. Genetic Parameters for Some Growth Traits of Local Breed of Goat in the United Arab

Records on 361,300 Yorkshire, 154,833 Duroc, 99,311 Hampshire, and 71,097 Landrace pigs collected between 1985 and 1999 in herds on the National Swine Registry STAGES program were used to estimate additive genetic (animal), common environmental (litter) and residual variances and covariances for lean growth rate, days to 113 kg, backfat, and loineye area. Analysis was by the REMLf90 program of I. Misztal using a multiple-trait animal model with fixed effects of contemporary group and sex and random effects of animal, litter, and residual. Estimates of heritabilities were 0.35, 0.40, 0.52, and 0.43 for lean growth rate, 0.43, 0.47, 0.57, and 0.46 for days to 113 kg, 0.35, 0.41, 0.55, and 0.49 for backfat, and 0.44, 0.43, 0.50, and 0.38 for loineye area in Yorkshire, Duroc, Hampshire, and Landrace, respectively. Genetic correlations were -0.94, -0.86, -0.80, and -0.80 between lean growth rate and days to 113 kg, -0.32, -0.40, -0.25, and -0.41 between lean growth rate and backfat, and 0.40, 0.40, 0.36, and 0.36 between lean growth rate and loineye area in Yorkshire, Duroc, Hampshire, and Landrace, respectively. Estimates for heritabilities and genetic correlations were consistent across breeds except for higher heritabilities for the Hampshire breed. Estimates for heritabilities across the four breeds for lean growth rate, days to 113 kg, backfat, and loineye area were 0.43, 0.48, 0.45, and 0.44, respectively. Genetic correlations across the four breeds between lean growth rate and days to 113 kg, backfat, and loineye area were -0.85, -0.35, and 0.38, respectively. Litter effects were generally small (< 0.1) except 0.12 for both days to 113 kg and loineye area in the Yorkshire breed. The results indicate that lean growth rate should be used as an important selection criterion in genetic improvement of pigs.