Records of 192 Hard henu cattle pertaining to first lactation traits over a period of 6years from 2008 to 2014were collected from history cum pedigree sheets maintained at Cattle breeding farm, Department of Animal Genetics and Breeding Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar. Data were analysed by LSML(Harvey, 1990) using mixed linear model having effect of sire as random and that of year and season of calving as fixed. The first lactation traits studied were first lactation milk yield (FLY), first lactation length (FLL) first service period (FSP) and first calving interval (FCI). The overall least squares means FLY, FLL, FSP and FCI were averaged as 2392.92±70.45 kg,317.70±15.87days, 160.20± 18.08 days and 448.90± 15.13 days, respectively. The effect of period of calving was not significant for all the first lactation traits under study except for FSP. Similarly, the effect of season of calving was not significant for all the first lactation traits except for FSP. The heritability estimates for different first lactation traits were obtained as 0.27±0.34, 0.14±0.39, 0.13±0.38and 0.21±0.26forFLY, FLL, FSP and FCI, respectively. The genetic correlation among first lactation traits were positive and varied from 0.16 to 0.59 except the genetic correlation of FLL with FSP and FCI which was low and negative. The phenotypic correlation among first lactation traits were low to high positive and varied from 0.11 to 0.76, respectively.

RESUMO -No presente trabalho, 180 fêmeas da raça Nelore, provenientes de oito rebanhos, foram analisadas quanto aos marcadores microssatélites TEXAN15, BM1224 e CSFM50 e aos polimorfismos de comprimento de fragmentos de restrição (RFLP) nos locos κ-caseína, β-lactoglobulina e hormônio de crescimento (GH). Com exceção de GH, todos os marcadores foram polimórficos na amostra estudada. Os valores de heterozigosidade, diversidade gênica, conteúdo de informação polimórfica (PIC) e probabilidade de exclusão de paternidade (PE) foram estimados. Os maiores valores de PIC (0,685) e PE (0,521) foram obtidos para o marcador BM1224.Palavras-chave: bovino, DNA, marcador, microssatélite, Nelore, RFLP Molecular Characterization of a Nellore Beef Cattle Sample Using Microsatellites and Candidate GenesABSTRACT -In the present work, 180 Nellore females from eight herds were analyzed for TEXAN15, BM1224 and CSFM50 microsatellites and for the restriction fragments polymorphism (RFLP) at the locos κ-casein, β-lactoglobulin and growth hormone (GH). Excepted for GH, all markers were polymorphic in the studied sample. The values of heterozigozity, gene diversity, polymorphic information content (PIC) and paternity exclusion probability (PE) were estimated. The highest PIC (0.685) and PE (0.521) values were obtained for microsatellite BM1224.Key Words: bovine, DNA, marker, microsatellite, Nelore, RFLP 1 Departamento de Genética e Evolução -UFSCar, São Carlos -SP. E.mail: jtalhari@terra.com.br; matamb@terra.com.br 2 EMBRAPA -CPPSE, São Carlos, SP. E.mail: mauricio@cppse.embrapa.br; tambasco@zaz.com.br; luciana@cppse.embrapa.br 3 Departamento de Produção Animal -ESALQ, Piracicaba -SP. E.mail: llcoutin@carpa.ciagri.usp.br IntroduçãoDevido a sua importância econômica e cultural, estudos das relações genéticas entre rebanhos bovinos têm sido, historicamente, uma área ativa da sistemá-tica biológica. A caracterização de determinada raça pode ser feita por suas propriedades fenotípicas, morfológicas e fisiológicas, origem, habitat, distribuição geográfica, produção e parâmetros genéticos

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