Crossbreeding and new beef cattle breeds in Brazil.198

BARBOSA, P. F.

DUARTE, F. A. M.

Crossbreeding and new beef cattle breeds in Brazil

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Rev. Brasil. Genet.12, 3 - Supplement, 257-301 (1989)(Brazil, J. Genetics)sOSI ~qPROCI-1989.00006BAR1989SP-1989.00006CROSSBREEDING AND NEW BEEF CATTLE BREEDS IN BRAZILPedro Franklin Barbosa 1 and Francisco A. Moura Duarte?ABSTRACfData from both crossbreeding experiments and new breed development projects carriedout in Brazil are reviewed in this paper, with the purpose of summarizing the results as far as theutilization of animal genetic resources is concerned. We consider the relative importance of díffer-ences, if any , among the strategies for utilizing animal genetic resources. These average relativedifferences (ARD) should be estimated for characters of economic importance to beef cattleproducers and expressed in relation to the most commonly used genetic resources in a given regionar country. The strategies of utilizing animal genetic resources for beefproduction (E = Europeanbreeds; Z = Zebu breeds; and NB = New breeds) may be classified , íf one considers the differenttypes of animals resulting from their utilization, into 5 classes: 1 - purebred breeding (E and Zbreeds); 2 - F 1 production (E x Z, Z x E, E x E, Z x Z, NB x E, and NB x Z crossbreedingprograms); 3 - backcross production (to either E ar Z); 4 - three-cross production (three-breedcrossbreeding systems) ; and 5 - new breed development and utilization.Average relative differences (ARD), for a given characteristic, were estimated from datareported in the literature, as the relative difference (%) between means of different types of animais(purebred European, purebred Zebu, F 1, backcross, three-cross and new breed). These ARDestimates were then expressed as a proportion of that of purebred Zebu cattle (ARD = 100), with-out doubt the most common animal genetic resource for beef production in Brazil. Sufficient datawere only available (for ali types of animais and from at least two different experiments) for birthweight, weaning weight, liveweight at slaughter, carcass weight, and dressing percentage. Netaverage relative differences (NARD), obtained by averaging the ARD for these 5 characteristics ofanimais frorn the 5 classes of strategies defined above, were compared to that obtained by utilizingpurebred Zebu cattle (NARD = 100) and the following results were obtained: three-cross production1 EMBRAPA, UEPAE de São Carlos, 13560 São Carlos, SP, Brasil.2 Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo,14049 Ribeirão Preto, SP, Brasil.

Crossbreeding and new beef cattle breeds in Brazil.

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