Prototipo de evaluación genética nacional para fertilidad de vaquillas Simmental-Simbrah y Charolais-Charbray

The objective of this study was to develop a prototype of multibreed genetic evaluation for heifers’ fertility (FERT) in Simmental-Simbrah and Charolais-Charbray populations. Information from 49,943 Simmental-Simbrah females born between 1984 and 2011 (EvSim) and 49,871 Charolais and Charbray females (EvChar), born between 1990 and 2011 were used.  For the analysis, a one was assigned when a heifer calved before 1,281 d of age, otherwise a zero was assigned. Variance components estimates and breeding values were obtained by fitting a linear mixed model for a single trait. Estimates of heritability were similar, 0.07 ± 0.008 and 0.06 ± 0.008, for EvSim and EvChar, respectively. Median number of heifers per contemporary group was 10, with an interquartile range from 5 to 20, in both cases, EvSim and EvChar. Median number of paternal half sibs per family was 5 for both, EvSim and EvChar. The ranges of expected progeny differences (EPD) for FERT were: -5.79 to 8.72, -9.56 to 8.84, -7.94 to 8.22, and -7.29 to 6.14, for Simmental, Simbrah, Charolais and Charbray, respectively. Heritability estimates suggest that there may be genetic response to selection of FERT in the populations evaluated. Estimated genetic trends suggest a favorable genetic change of fertility in the four breeds during the period 2007 to 2011. The ranges of the EPD allowed identification of outstanding sires for FERT.