Daily gains during four postweaning 28‐day periods, cumulative daily gains, market weight and market age were analyzed for 450 backcross pigs (Exp. 1) and 616 two‐breed cross pigs (Exp. 2). The backcross pigs were produced by the mating of purebred Duroc boars to crossbred Duroc × Yorkshire (DY) sows, purebred Hampshire boars to crossbred Hampshire × Yorkshire (HY) sows and purebred Landrace boars to crossbred Landrace × Yorkshire (LY) sows. Breed designations for backcross pigs were 3D1Y, 3H1Y and 3L1Y. The two‐breed cross pigs were produced by the mating of backcross (3D1Y, 3H1Y, 3L1Y) sows to purebred Yorkshire boars. Breed designations for two‐breed cross pigs were 5Y3D, 5Y3H and 5Y3L. In both experiments, pigs were fed ad libitum finely ground, 18% crude protein, normal (3.9%) and high (8.8%) fiber diets containing 3,428 and 2,910 kcal metabolizable energy/kg, respectively. In Exp. 1, daily gains of 3L1Y pigs were greater during periods 1 and 2 and smaller during periods 3 and 4 than were those of the 3D1Y and 3H1Y pigs. In Exp. 2, daily gains of the 5Y3D pigs were superior to those of the 5Y3H and 5Y3L pigs. In both Exp. 1 and 2, Duroc crosses were 7 days younger than Hampshire and Landrace crosses at market weight. In Exp. 1, pigs fed 3.9% fiber diet gained 13, 5 and 26% faster in periods 2, 3 and 4, respectively, and were .8 kg heavier and 13 days younger at market than pigs fed the 8.8% fiber diet. In Exp. 2, the advantage in daily gain for pigs fed the 3.9% fiber diet was 7, 22, 7 and 17% in periods 1, 2, 3 and 4, respectively, and these pigs were 13 days younger at market weight. In both Exp. 1 and 2, the breed cross × diet interaction was significant only for daily gain in period 4. In both experiments, the within diet linear regressions of daily gains, market weight and market age on litter size, weight and age at weaning were non‐significant. Within experiment linear regressions of daily gains, market weight and market age on pig weaning traits showed that litter size had the least effect and weaning weight the greatest effect on postweaning daily gains, market weight and market age.