Background:

The existence of genotype-environment interaction (GEI) implies the occurrence of a change of merit order under different environmental conditions, which may be important from economic and practical standpoints. The aim of this study was to determine the possible existence of GEI in Santa Gertrudis cattle, in Cuba.

Methods:

The weights of 18-month old males and females were adjusted to 540 days of age (AW). The animals belonged to three cattle raising companies, with 4 529 animals born between 1981 and 2016, from 161 stud bulls. The data were narrowed down, excluding the studs with less than 10 descendants, and same-age group (SA) with less than three animals. Two data sets were made: animals with a high final adjusted weight (HAW), and animals with low adjusted weight (LAW), which were above and under the mean, respectively. A single-character animal model was used, considering SA (herd-year-season) and sex as fixed effects; animal and residue were deemed as a random effect. A two-character model had the same effects, including HAW and LAW as two independent traits. Regarding the stud bulls represented in the two environments, the Pearson and Spearman correlations were estimated among their genetic values.

Results:

The single-character heredities (h2) were, 0.37 ± 0.09, and 0.14 ± 0.04, and 0.22 ± 0.09, and 0.11 ± 0.04, in the two-character model for PAA and PAB, respectively. The genetic correlation was 0.82, but the Pearson and Spearman correlations were, 0.04 and 0.18, which indicated a variation in stud merit order and GEI.

Conclusions:

Heredities in the AW were moderate and higher under better conditions, regardless of the model. This methodology demonstrated that under contrasting environments there is evidence of GEI upon changes in stud merit order.