Resumen

GOMEZ GIL, Manuel Guillermo et al. Reproduction of Brahman females from two herds participating in a genetic improvement program. Zootecnia Trop. [online]. 2010, vol.28, n.2, pp.001-001. ISSN 0798-7269.

To evaluate Brahman female reproduction in two-herd population participating in a genetic improvement program located in Cojedes and Portuguesa plains, heifer pregnancy (PN), pregnancy (PG) and Calving (PT) were studied. For the analysis a logistic regression models with repeated measurement and maximum likelihood method was carried out. Herd (H) and year of service season (A) were included as fixed effects for PN, and H, A and age at service season (E) for PG and PT. Means for PN, PG and PT were 72,0%, 69,0% y 62,7%, respectively. A and H were highly significant for all traits and E for PG and PT. A showed a wide range of variation of 55,6; 26,4 and 32,3 percentage points between worst and best year for PN, PG and PT, respectively. The herd located in Cojedes had 32,4; 11,6 and 16,3 percentage points of superiority. The worst E was 3 years with 30,2 and 24,4 % of means, while the best E were 8 and 9 years with 66.6 and 58,9 % for PG and PT, respectively. Results obtained in this research showed that it is necessary to analyze information from multi-herds populations to characterize nongenetic factors affecting the reproduction of Brahman females.

Palabras clave : Brahman; reproduction.

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