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Data from 9 studies were compiled to evaluate the effects of 20 yr of selection for postweaning weight (PWW) on carcass characteristics and meat quality in experimental herds of control Nellore (NeC) and selected Nellore (NeS), Caracu (CaS), Guzerah (GuS), and Gir (GiS) breeds. These studies were conducted with animals from a genetic selection program at the Experimental Station of Sertãozinho, São Paulo State, Brazil. After the performance test (168 d postweaning), bulls (n = 490) from the calf crops born between 1992 and 2000 were finished and slaughtered to evaluate carcass traits and meat quality. Treatments were different across studies. A meta-analysis was conducted with a random coefficients model in which herd was considered a fixed effect and treatments within year and year were considered as random effects. Either calculated maturity degree or initial BW was used interchangeably as the covariate, and least squares means were used in the multiple-comparison analysis. The CaS and NeS had heavier (P = 0.002) carcasses than the NeC and GiS; GuS were intermediate. The CaS had the longest carcass (P < 0.001) and heaviest spare ribs (P < 0.001), striploin (P < 0.001), and beef plate (P = 0.013). Although the body, carcass, and quarter weights of NeS were similar to those of CaS, NeS had more edible meat in the leg region than did CaS bulls. Selection for PWW increased rib-eye area in Nellore bulls. Selected Caracu had the lowest (most favorable) shear force values compared with the NeS (P = 0.003), NeC (P = 0.005), GuS (P = 0.003), and GiS (P = 0.008). Selection for PWW increased body, carcass, and meat retail weights in the Nellore without altering dressing percentage and body fat percentage.

RESUMO -Quarenta e quatro machos inteiros provenientes de rebanhos selecionados para peso aos 378 dias (P378), nascidos em 1995, foram confinados na Estação Experimental de Zootecnia de Sertãozinho, Estado de São Paulo. As amostras, representando a média geral de P378 em cada rebanho, foram formadas por oito animais Guzera (GuS) e nove para cada um dos grupos Gir (Gi), Nelore (NeS), Nelore Controle (NeC) e Caracu (Ca). O abate ocorreu aos 580 dias de idade e condição corporal 8, em uma escala de 1 a 9. As médias mínimas e máximas ajustadas, para as principais características, envolvendo todos os grupos, foram: ganho médio diário de peso, 817 (NeC) e 1061 g (Ca); peso de abate (PAB), 408,3 (Gi) e 513,6 kg (Ca); peso de carcaça (PCAR), 230,2 (Gi) e 285,0 kg (Ca); rendimento de carcaça, 55,6 (GuS) e 58,1% (NeC). No corte entre a 9ª-11ª costelas, foram: músculo: 55,7 (NeC) e 64,7% (Ca); gordura: 18,6 (Ca) e 26,9% (NeC); osso: 16,7 (Ca) e 19,2% (Gi); espessura de gordura (ESPGOR): 6,4 (Ca) e 7,5 mm (GuS); área de olho de lombo: 62,8 (Gi) e 76,6 cm 2 (Ca); força de cizalhamento: 4,4 (Ca) e 5,4 kg (Gi) e perdas totais no cozimento: 23,4 (NeC) e 26,1% (Ca). Considerando o grupo Nelore, a seleção para peso provocou maiores PAB e PCAR, sem alterar o rendimento, a composição física da costela ou a qualidade da carcaça e da carne. Animais Ca tiveram maior PAB, porém menor rendimento, maior musculosidade e menores níveis de gordura e espessura de gordura. Já GuS, com rendimento semelhante ao Ca, apresentou maior ESPGOR. Não se observaram diferenças entre os grupos genéticos quanto aos índices de maciez e perdas no cozimento da carne.Palavras-chave: composição corporal, força de cizalhamento, Gir, Guzerá, maciez da carne, Nelore, rendimento de carcaça Breed and Selection for Post-Weaning Weight Effects on Feedlot and Carcass Traits for the 15 th Progeny of Sertãozinho (SP-Brazil) Zebu and Caracu HerdsABSTRACT -Forty-four young bulls of herds selected for weight at 378 days of age (W378), born in 1995, were confined at the Sertãozinho Experimental Station, São Paulo State, Brazil. The samples, representing the W378 overall mean for each herd, were formed by 8 Guzera bulls (GuS) and by 9 bulls of each one of the groups Gir (Gi), Nelore (NeS), Nelore Control (NeC) and Caracu (Ca). The slaughter was carried out when the animals were at 580 days of age, with a body condition score averaging 8, in a 1-9 scale. The minimum and maximum adjusted means for the main traits, including all groups, were: average daily gain: 817 (NeC) and 1,061 g (Ca); slaughter weight (SW): 408.3 (Gi) and 513.6 kg (Ca); carcass weight: 230.2 (Gi) and 285.0 kg (Ca); dressing percentage (DP): 55.6 (GuS) and 58.1% (NeC). In the 9 th -11 th rib section: muscle: 55.7 (NeC) and 64.7% (Ca); fat: 18.6 (Ca) and 26.9% (NeC); bone: 16.7 (Ca) and 19.2% (Gi); fat thickness (FT): 6.4 (Ca) and 7.5 mm (GuS); loin eye area: 62.8 (Gi) and 76.6 cm 2 (Ca); Warner-Bratzler shear force: 4.4 (Ca) and 5.4 kg (Gi); total cooking losses: 23.4 (NeC) and 26.1% (Ca). Considering the N...

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