Reproducción de hembras Brahman en dos reba？os pertenecientes a un programa de mejora genética

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.