Interactive effects of genotype x environment on the live weight of GIFT Nile tilapias

Abstract

In this paper, the existence of a genotype x environment interaction for the average daily weight in GIFT Nile tilapia (Oreochromis niloticus) in different regions in the state of Paraná (Brazil) was analyzed. The heritability results were high in the uni-characteristic analysis: 0.71, 0.72 and 0.67 for the cities of Palotina (PL), Floriano (FL) and Diamond North (DN), respectively. Genetic correlations estimated in bivariate analyzes were weak with values between 0.12 for PL-FL, 0.06 for PL and 0.23 for DN-FL-DN. The Spearman correlation values were low, which indicated a change in ranking in the selection of animals in different environments in the study. There was heterogeneity in the phenotypic variance among the three regions and heterogeneity in the residual variance between PL and DN. The direct genetic gain was greater for the region with a DN value gain of 198.24 g/generation, followed by FL (98.73 g/generation) and finally PL (98.73 g/generation). The indirect genetic gains were lower than 0.37 and greater than 0.02 g/generation. The evidence of the genotype x environment interaction was verified, which indicated the phenotypic heterogeneity of the variances among the three regions, weak genetic correlation and modified rankings in the different environments.

Evaluating the growth of genetically improved tilapia Oreochromis niloticus reared at different temperatures

“…Since Brazil is a continental country with many options for fish production systems, it is important to evaluate Genotype × Environment to gain insight on better performance in tilapia production since phenotype is a consequence of genotype under the influence of environment (Ponzoni et al, 2008;Oliveira et al, 2017). Similar studies were conducted in Malaysia (Khaw et al, 2009), the Philippines (Eknath et al, 2007) and Brazil (Oliveira et al, 2017) where the responses from GIFT fish were evaluated under different environmental conditions.…”

Growth curve of Nile tilapia from different families of the AquaAmérica variety

“…(2015), who obtained 338.28 g over a period of 160 days of cultivation of the GIFT variety. The observed difference in weight between the studies with Nile tilapia is due to genetics -varieties (Marengoni et al, 2015), environment (Oliveira et al, 2017) and density and/or production system (Ribeiro, 2001). The greater weight found in families AA10 and AA16 at the fourth and fifth biometric assessments indicates the superiority of these families over the others, especially family AA8 at the fourth biometric assessment (37.2% lower than family AA10) and family AA6 at the fifth assessment (37.1% lower than family AA10).…”

“…The greater body width W1 of families AA5, AA16, AA19 and AA20 and body widths W2 and W3 in family AA19 at 133 days; and the greater body widths W2 and W3 in family AA19 and body widths W1 and W2 in family AA10 at 181 days indicate a change in body widths between families from the fourth to the fifth biometric assessment. can perform differently in a given production environment (Oliveira et al, 2017).…”