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New breeds can be developed by combining two or more breeds into a composite population, thereby capitalizing on complementarity and retained heterosis. Evaluation of breed formation across generations has not been performed at the molecular level; therefore, we used Brangus cattle (3/8 Brahman x 5/8 Angus) as a model to identify the dynamics of new breed formation across 10 generations. Genotypic data (777,962 SNP) from 68 Brahman, 95 Angus and 59 Brangus prominent AI sires born from 1970 to 2010 were evaluated. Their pedigrees were used to calculate the number of complete Brangus generations using the OptiSel package in R 3.4.2. After standard SNP data filters and linkage disequilibrium pruning, 158,264 SNP genotypes from 220 bulls were chosen. ADMIXTURE analyses were executed using autosomal markers by chromosome, setting K equal to two and three. Brangus animals had 70.4% of Angus composition in all autosomes versus the expected 62.5% (t-test, P< 0.001). When K = 3, the establishment of the Brangus cluster was observed across the genome with a proportional assignment > 0.5. The sex chromosomes deviated from the autosomal pattern. Chromosome X had a high Angus proportion (83%) conserved across generations and Brahman contributed only to 9% of the Y chromosome. Regression analyses of cluster formation among autosomes and across generations showed (P< 0.001) that Angus (β = -0.07) and Brahman (β = -0.03) clusters decreased while Brangus cluster increased (β = 0.10, R2= 0.43). Regressions by each autosome followed a similar pattern. Formation of the Brangus cluster became stable after the 5thgeneration. These results provide a view into the evolution of a new breed.

New technologies that aim to potentiate the productive capacity of the areas currently exploited have been introduced in Brazilian beef cattle. The cross between breeds and the use of integrated production systems are strategies with potential to increase production with an increase in the quality of the final product, the meat. The aim of this research was to evaluate the traits of carcass and meat of Nellore (N) and Nellore × Angus (F1) heifers, recreated in two forage production systems with and without crop-livestock integration (CLI). The experiment was carried out in an area of 9 ha, where were evaluated 36 calves, with initial age of approximately 7 months and live weight of 180 kg, being 18 Nellore and 18 Nellore × Angus, divided into high-investment treatments (HI), pasture of Urochloa brizanthacv. Paiaguás, reformed with the maize consortium, Urochloaand guandu (CLI), and low investment (LI), pasture of Urochloa decumbens. The animals were slaughtered at approximately 19 months. The data collected at slaughter were submitted to analysis of variance, considering the effect of genetic groups and treatments (different pastures), as well as the interaction between them. Correlation analysis was also performed to verify the relationship between meat and carcass variables measured. The F1 animals showed higher carcass weight, round thickness, carcass length and rib eye area (REA) than the Nellore animals. It was observed superiority for REA, fat thickness, marbling, carcass length and hot carcass weight. The interaction between genetic group and treatment was significative only for REA, being that the animals of the treatment HI differed from those LI treatments (72.94 vs 66.89 cm2). The measure of carcass length and REA showed high and positive correlation with carcass weight, as expected. The shear force showed high and negative correlation with the coloration parameters (L, a, b). It was observed superiority of F1 animals considering the traits of carcass and meat quality. Can be perceived that the CLI system provided increase in the quantity and quality of the meat produced.