Background:

The genetic parameters are necessary in order to formulate optimal genetic improvement programs. Objective. To determine the genetic parameters for growth traits in animals subjected to performance tests (PT) of the Santa Gertrudis breed.

Methods:

A database made up of 4,607 records of animals belonged to three genetic enterprises between years 1981-2016. The traits studied were: birth weight (BW), weaning weight (WW), final weight in the adjusted to 540 days of age (FWA), mean daily gain (ADG) and weight for age (WA). The groups of contemporaries were made up of the combination of herd, year and season of birth (four-month period), with no less than 3 animals. Variance and covariance components and genetic parameters were estimated using the restricted maximum likelihood (REML) procedure and the derivative-free algorithm using the MTDFREML software.

Results:

Heritabilities were: 0,08 ± 0,02; 0,18 ± 0,02; 0,28 ± 0,07; 0,05 ± 0,02 y 0,26 ± 0,07 for BW, WW, FWA, ADG y WA, respectively. The genetic correlations were all positive with the exception between BW and ADG (-0.11) and ranged between 0.10 (BW and PPE) and 0.98 (WW and FWA; FWA and ADG). The phenotypic correlations were lower than the genetic ones.

Conclusions

The FWA in (PT) which is the main selection criterion, shows the highest heritability and has positive genetic correlations with the other traits, so the simultaneous improvement of all should be expected. FWA, ADG and WA are determined by the same additive genes.